613 lines
46 KiB
Markdown
613 lines
46 KiB
Markdown
<p align="center">
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<picture>
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<source media="(prefers-color-scheme: dark)" srcset="assets/banner-dark.svg">
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<img src="assets/banner-light.svg" alt="apk-reverse" width="100%">
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</picture>
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</p>
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<p align="center">
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<b>English</b> · <a href="README.zh-CN.md">简体中文</a>
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</p>
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<p align="center">
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<a href="https://github.com/newliver666/apk-reverse/stargazers"><img src="https://img.shields.io/github/stars/newliver666/apk-reverse?style=flat-square&label=stars&color=49454F" alt="stars"></a>
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<a href="https://github.com/newliver666/apk-reverse/network/members"><img src="https://img.shields.io/github/forks/newliver666/apk-reverse?style=flat-square&label=forks&color=49454F" alt="forks"></a>
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<a href="LICENSE"><img src="https://img.shields.io/github/license/newliver666/apk-reverse?style=flat-square&color=49454F" alt="license"></a>
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<img src="https://img.shields.io/badge/python-3.9%2B-49454F?style=flat-square&logo=python&logoColor=white" alt="python">
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<img src="https://img.shields.io/badge/platform-android-49454F?style=flat-square&logo=android&logoColor=white" alt="android">
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<a href="https://github.com/newliver666/apk-reverse/actions/workflows/ci.yml"><img src="https://img.shields.io/github/actions/workflow/status/newliver666/apk-reverse/ci.yml?style=flat-square&label=ci&color=49454F" alt="ci"></a>
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</p>
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<p align="center">
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<a href="#what-it-is-good-at">Capabilities</a> · <a href="#structure">Structure</a> · <a href="#install">Install</a> · <a href="#requirements">Requirements</a> · <a href="#read-this-first">Failure catalogue</a> · <a href="#scope">Scope</a> · <a href="#repository-maintenance">Maintenance</a> · <a href="#disclaimer">Disclaimer</a>
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</p>
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# apk-reverse
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An Agent Skill for Android APK reverse engineering, debloating, ad removal, surgical
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dex patching, repacking, and runtime/server analysis.
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It is a **skill**, not a tutorial: it is written to be loaded by an agent (Claude Code,
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Codex, or any harness that supports the Agent Skills format) while it works, so it is
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organized for progressive disclosure — a short decision-oriented `SKILL.md`, detailed
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references loaded only when a step needs them, and parameterized scripts you can run
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directly.
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## How an agent is expected to consume this
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`SKILL.md` is deliberately written as a **procedure with gates** rather than as advice, because the
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observed failure mode is not ignorance — it is a model reading the whole thing, agreeing with it, and
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then reasoning from first principles anyway.
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So there are four things in the body that are meant to be *acted on*, not read:
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- **Four override rules (R1–R4).** Where they conflict with the current plan, they win until evidence
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overrides them.
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- **A symptom index.** Each row is a failure that has already been paid for. **A matching row is a
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stop signal**: load that file before running another command, rather than after a few more attempts.
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Reasoning past a known symptom is how the same hours get spent twice.
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- **Four gates (G1–G4),** each an action with a pass criterion. "I understand the idea" does not clear
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a gate. They exist so that classification, environment truth and a control build happen *before*
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the first patch, not after the third failure.
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- **A two-strike rule and stop conditions.** Two failures of the same shape mean the model is wrong,
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not the parameters. The third variant of a hypothesis that already failed twice is where rounds go
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to die.
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And one thing at the end that is meant to be *withheld*: **"done"** has a definition (six items). A
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clean log is not one of them. Anything short of all six is a checkpoint, and should be reported as a
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checkpoint with what remains.
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If you are an agent reading this: the cheapest possible first command is
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`python skills/apk-reverse/scripts/doctor.py`. It tells you which of these tools exist here, which
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scripts can actually run, and whether something in the environment is already poisoning your
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measurements.
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## What it is good at
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- Deciding **fast** whether a request is even achievable client-side, instead of
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burning hours on a paywall that is enforced by a server.
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- Deciding **what form the deliverable must take** before any work starts — an
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unrooted, self-contained artifact is a different problem from "make it work on this
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machine", and confusing the two is the most expensive drift in this domain.
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- Choosing the **safest patch layer** for a given change, and avoiding the layers that
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break the app.
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- Catching the repack failure that looks like success: an app that installs, launches and
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renders perfectly while **every signed request is rejected**, because the client derives its
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request-signing key from its own signing certificate.
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- Separating **your own mistakes from the app's or the server's problems** — a
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feature-scoped failure (login, registration, payment) is often a TLS/certificate issue on
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one code path, not a consequence of the patch you just built. Device state, a dead device
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server and clock drift masquerade the same way.
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- Establishing **which architecture and which library are actually executing**, rather
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than trusting what the manifest ships or what the device claims.
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- Working through **packed/hardened targets**: identifying the packer, unpacking, and turning a
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memory dump back into a patched, installable APK.
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- Handling a **hardened library that terminates the process on purpose** — including the
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deliberate-crash shape (`fault addr 0x4`) that looks exactly like an ordinary null-dereference
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bug, and the "neutralise it, but never by making it *not return*" rule that decides whether the
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fix works or freezes the whole app in a way that looks nothing like the cause.
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- Knowing **which tools to reach for and where each one lies** — including the ones that only
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exist as a GUI, so you ask for a human instead of silently substituting a weaker method.
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- Making a patched build **stay** patched: neutralising version checks, forced-upgrade dialogs and
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self-update installers so the work cannot be switched off remotely — and recognising the
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hot-update/remote-config channel that can quietly undo it without any version change.
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- Separating a **client-side sign-in gate** (patchable) from an **account-scoped resource** (empty
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because the server has nothing to answer with), and knowing that forging a session produces a state
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worse than being signed out.
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- Keeping a **long task honest**: a live record, graded conclusions, calibrated timeouts, and
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bounded waits, so progress is not lost and the same mistake is not made twice.
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- Avoiding the specific mistakes that produce an APK that builds perfectly and dies at
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runtime.
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- Deciding **what the deliverable should be when an APK is not an option** — a repack refused by
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several independent checks is *blocked*, not expensive, and the fallback ladder is a system-level
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module, a local RPC service, or an honest report with a stated boundary.
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- Telling a **real memory dump from an extraction-shell skeleton**, and knowing which recovery route
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applies — including the root-side dump for when `frida` itself is refused. What the measurement can
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and cannot see is in `skills/apk-reverse/references/advanced-unpacking.md`.
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- **Calling a routine instead of reversing it** when reversing costs more than invoking: emulated
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execution on the host, or a live function service-ified over Frida RPC.
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- Reading **instruction-level execution evidence** when a native function has been flattened into a
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state machine by OLLVM — including the two ways Stalker was measured to bite back on a real device.
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- Recognising when **userspace hooking cannot reach the check at all** (raw `svc` syscalls,
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`init_array`-early detection), what the next layer up and down can actually do, and when escalating
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is the wrong answer.
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- Working **protocols that are not REST** — protobuf without a schema, gRPC, QUIC/HTTP3 — and
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native-side certificate pinning that ignores the system trust store.
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- Working **from the phone itself**: MT Manager's edit/repack/sign flow and its APK MCP surface,
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LSPosed Manager, and on-device data inspection, alongside the PC toolchain rather than instead of it.
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- Telling **Java2C apart from an extraction shell** before spending hours hunting a decrypted DEX that
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does not exist at any point in the process lifetime — the code was compiled into a `.so`.
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- Handling a build that arrives as a **split APK / App Bundle set**: reading the set off a device,
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signing every member with one keystore for `pm install-multiple`, or merging code/native members
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into a standalone APK when that is legal.
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- Working a **real Dex VMP** with the known-plaintext differential — which links can be automated and
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which cannot, what a compiled fixture can and cannot reach, and how to *prove* a derived
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private-opcode table instead of asserting one.
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- **Publishing what it learns without publishing the target** — a scanner that reports identity
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shapes with their context, an explicit list of what must *not* be redacted (tools, libraries,
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protocol fields, CVEs, hardening products, public crackmes) because redacting those destroys the
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reusable part, and exit codes that gate a commit.
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- Reading a **precedent** before repeating work this repository already converged on: the positive
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half of the record, with the route including its dead ends, a grade on every assertion, and the
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files the case says to write back to.
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## Structure
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`SKILL.md`, `references/` and `scripts/` are all inside the skill directory, `skills/apk-reverse/`.
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Everything at the repository root is maintenance tooling shared across skills, not part of an
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installed skill.
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```
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SKILL.md a procedure with gates, not background reading:
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how-to-use -> four override rules (R1-R4)
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symptom index (a matching row is a stop signal)
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four gates (G1-G4, actions with pass criteria)
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thirteen classification questions
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the workflow, with a per-step skip condition and a two-strike rule
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what "done" means -> stop conditions -> constraints -> indexes
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references/ loaded on demand, one topic each
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recon.md identify packer, SDKs, code location, tamper checks; unpacking
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server-config-and-updates.md
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the most common shape of "ad" and the one usually mis-diagnosed:
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the server supplies UI the client renders (launch screen, popup,
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announcement, tab set). The two-layer fetch that proves it, how to
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find the config DTOs by the field names data classes keep, why you
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patch the decision and not the data, deciding the scope of "remove",
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and remote re-enable / cached config durability
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byte-level-patching.md equal-length byte edits: why they beat method rebuilding (measured),
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locating an instruction's exact offset without scraping listings,
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the instruction width traps that desynchronise a decode, neutralise
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a branch vs redirect it, dex header integrity field order, and the
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verifier's move-result rule
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packers.md hardened targets: rejection signals, measuring the validation
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boundary with single-variable tests, choosing a native host
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code-virtualization-and-custom-linkers.md
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the layer between "packed" and "clean": whole classes turned into
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`native` declarations, a private loader whose SONAME does not match
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its filename, an embedded self-decrypting payload, a Java-layer
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"signature killer" that logs success while a native check kills you.
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The keep-it/drop-it deadlock, how to separate the *checker* from the
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*implementation*, and the string-redirect technique that ends it
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without neutralizing anything
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framework-runtimes.md Flutter / React Native / Unity: which layer owns the UI, and how to
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find logic when there are no symbols (string encoding traps)
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dart-aot.md Dart AOT in depth: version pinning and building a matching decompiler,
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the object pool and reference indexes, register/boolean conventions,
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the three signatures that identify business logic, locating, patching.
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Begins with the snapshot-decoding front end it depends on (aotopsy or
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blutter) because the pool listing is an input, not something this skill
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produces itself
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native-and-so.md .so hosts, DT_NEEDED vs JNI_OnLoad, relocation limits,
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relocation-free bootstrapping, replacing Java methods natively,
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and which ABI/library is *actually loaded and executing*
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native-tamper-and-suicide.md how a hardened library kills its own process: the visible
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mechanisms, how to tell which one actually fires, how to find the
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site, forged section headers, function boundaries from
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PT_GNU_EH_FRAME, scanner traps, and neutralising safely
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detection-and-anti-analysis.md when the app fights back or the tool cannot run here: telling
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detection apart from a broken environment, deciding by cost instead
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of escalating, recognising an environment where dynamic analysis
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simply does not work, and keeping the "blocks my analysis" question
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separate from "blocks the deliverable"
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toolchain.md what to install, how to invoke it non-interactively, which tools
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are GUI-only, version-alignment traps, working offline,
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**"not on PATH" is not "not installed"**, and which signer to use
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long-task-discipline.md live record, conclusion grading, drift control, timeout and
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wait calibration, deliverable-form drift, captures-you-never-looked-at,
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long-context decay, handover
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ad-removal.md ad taxonomy, wrapper mapping, callback trap, global gates, verification
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updates-and-forced-upgrade.md keeping a patched build alive: locating the version check, the
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two-layer patch (no-op the routine, neutralise the comparison), what not
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to touch (manifest version, installer permission, host blocking),
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self-update and hot-update/remote-config channels, verifying that no
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version request is issued at all
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account-gates.md sign-in walls, forced phone binding, guest mode: telling a client-side
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gate (patchable) apart from an account-scoped resource (not), why
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fabricating a session is worse than staying signed out, and the
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unavoidable session loss after a reinstall
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signature-derived-keys.md when the app's own signing certificate is used as key material:
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detection greps, why offline extraction is unreliable, the
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hardcode-then-verify procedure
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membership-and-limits.md server vs client authority; what is and is not patchable
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server-api.md probe an app's API; prove who owns the gate
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tls-and-cert.md feature-scoped network failures: expired certs, dual trust chains
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third-party-builds.md auditing a "cracked"/"modded" APK before trusting it
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dex-patching.md patch-layer table + dexlib2 technique in depth
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patch-audit.md proving a patch *landed* and is *legal*: length-vs-bytes
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comparison, the equal-length-replacement blind spot, verifier-level
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legality (move-result adjacency) checked statically, text-matching
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patch traps, and reporting a missing patch
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repack-and-sign.md repack rules, unpack-and-repack, signing, post-install hazards
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runtime-data.md DataStore / SharedPreferences / SQLite / protobuf; when the app
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rewrites your edit, and decoding a value that looks encrypted
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dynamic-frida.md Frida setup, version pinning, the four-layer probe, hook strategy
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environment.md device/emulator setup, root, ADB, offline devices, log signals,
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emulator console control and recovery, preflight, look-at-the-screen
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verification.md the claim ladder; what "done" means
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desensitization-and-leak-scans.md
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publishing discipline: what must be desensitized and what must stay,
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the do-not-anonymize list, the leak scanner and its exit states, and
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the entry-point file as a prompt surface
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precedents/ the positive case library: route including dead ends, a grade per
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assertion, measured pit-falls, and the write-back checklist
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routing.md the on-demand inventory: every reference with when to load it, every
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script with what it does, and a mirror of the symptom index
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rasc-and-droidsaw.md the Rust re-implementation of the ASC indexer: measured speedup and
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identical class sets, the enum shape where it silently drops bodies,
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and how to build and verify it
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evidence-summary.md the condensation that ships with the skill: capability, one-line
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conclusion, strength, and the evidence you can actually open in an
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installed copy
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../evals/ NOT a spec directory either, but the location the Agent
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Skills guidance recommends: `evals.json` holds the
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with-skill / without-skill cases this skill has **not** run,
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with the method for running them written into the file
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../evidence/ NOT a spec directory: the machine-readable companions to the evidence
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summary reference above -- `capability-matrix.json` (the same rows with
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more fields), `tested-tool-versions.json` (versions and the probe behind
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each), `known-limitations.md` (the installer-facing limit list). Shipped
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inside the skill so an installed copy can answer "was this verified, and
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how strongly" without the repository
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pitfalls.md the failure catalogue -- read before building
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advanced-unpacking.md the dump landed but the bodies are empty: extraction-shell diagnosis by
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trivial-body ratio, FART-style active invocation and why its classic hooks
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died on Android 12-16, code_item splicing, the root-side dump for when
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frida itself is refused, and the honest VMP boundary
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lsposed-and-modules.md the repack is refused, so deliver a system-level hook module instead:
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module anatomy, a gradle-free build chain, scope configuration and how to
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verify injection, and the layer a Java module cannot reach
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emulation-and-rpc.md call the routine instead of reading it: Unidbg/Unicorn emulation and its
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environment-filling cost, versus service-ifying a live function over Frida RPC
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native-dbi-and-deobfuscation.md
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OLLVM shapes, Frida-Stalker traces, the trace-to-CFG route, the
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Stalker/QBDI/emulation decision, and two measured boundaries (a follow that
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delivers no events, and a crash from following a hot libc export)
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protocol-reverse.md protobuf without a schema, schema recovery from decompiled code, gRPC frame
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capture, the QUIC/HTTP3 limit, and native-side certificate pinning
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kernel-and-environment-hardening.md
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userspace hooking provably cannot reach the check: raw `svc`, init_array-early
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detection, what each root scheme hides, the kernel-route map with its version
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gate, and when to stop escalating
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on-device-tooling.md working from the phone itself: MT Manager edit/repack/sign and its APK MCP,
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LSPosed Manager, Termux+frida, on-device data inspection
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java2c-and-jni-sinking.md Java2C and JNI sinking, the two hardening shapes most easily confused
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with an extraction shell: the table that separates landing shell /
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extraction shell / VMP / Java2C / JNI sinking, why the code is in the
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`.so` and *never* in a dumped dex, and why a `Java_*` symbol search
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comes back empty (dynamic registration, `-fvisibility=hidden`)
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split-apk.md App Bundle / split APK sets: what the set is, pulling it off a device,
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merging into one APK vs signing the set as a unit, the install refusals
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and what each means, and making an installable fixture from a pulled set
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vmp-differential-analysis.md
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the known-plaintext differential for a real Dex VMP: which links can be
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automated and which cannot (the upload is the bottleneck), the coverage a
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compiled fixture can reach, how to *prove* a derived private-opcode
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table, smali generation, and when the route is closed
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coverage-and-limits.md the claim ladder applied to the skill itself: the evidence behind each
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covered item, the dependencies this skill does not ship, and what was
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never exercised
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handoff-boundaries.md where this skill ends and another discipline begins: the JNI form
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table, the packer-versus-loader split, and what "verified" means for
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each of the four deliverable forms
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scripts/ parameterized, path-agnostic
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doctor.py run this first: capability report + per-script runnability, finds
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tools installed off-PATH or as runnable jars, and surfaces the
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environment facts that poison experiments (clock skew, leftover
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adb forward / proxy, a device-side frida process already running)
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dexutil.py dependency-free dex reader: structural walk + exact instruction
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decode, dex header recompute/verify (correct checksum/signature
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order), branch-target and operand helpers. Library shared by the
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dex scripts, also runs standalone to dump one method with offsets
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dex_find_insn.py locate an instruction by decoded semantics and print its exact byte
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offset with context and both sides of any branch -- how you find a
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patch site instead of guessing offsets
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dex_patch_bytes.py equal-length byte patches from a JSON spec: semantic match, polarity
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pin via expect_next, equal-length enforcement, verifier check, dex
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header recompute, re-decode to prove it landed (--dry-run first)
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dex_check_verifier.py tier-3 check: does any conditional branch target a move-result
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(bypassing its producer)? Compares two builds and separates
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pre-existing findings from regressions your patch introduced
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coldstart.py cold-launch capture: timed screenshot burst + logcat signals +
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installed-build facts + launch timing, and warns when the foreground
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activity is not your app
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so_constpatch.py same-length in-place rewrite of an isolated string constant, for
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redirecting a library load instead of defeating a check
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smtool.py baksmali/smali wrapper with a configurable classpath
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dexpatch/ dexlib2 method-level rewriter (for changes that need new instructions)
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patch_smali.py method-body replacement in a smali tree
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dex_strpatch.py byte-level string patch with a string_ids ordering guard
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dex_classdiff.py prove a dex edit was surgical
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dex_strings.py strings/URLs/SDK markers without a decompiler
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dart_pool_strings.py recover literals from a Dart AOT snapshot (framed entries, the
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one-byte vs UTF-16 split, file offsets, run-length noise filter)
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dart_pprefs.py build/query the object-pool -> code-site index for a Dart snapshot
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dart_disasm.py annotated windowed disassembly of Dart AOT code + B/BL caller index
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find_refs.py count callers of a method before patching it
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repack.py rebuild APK, strip only signatures, keep META-INF/services/, write a
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4-byte-aligned archive (resources.arsc STORED+aligned), sign, verify;
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also split APK / App Bundle sets: inventory, sign every member with one
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keystore, or merge code/native members into a standalone APK
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devsh.py quoting-safe ADB shell helper
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usb_net_proxy.py give an offline device network over USB
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datastore_inject.py encode/inject AndroidX DataStore preferences safely
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probe_api.py probe an HTTP API with the right headers
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grab_crash.py recover stacks hidden by a crash-reporter SDK
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install_test.py install + launch health check with logcat signal scan
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frida_probe.js four-layer runtime probe (app net layer + OkHttp + java.net + exceptions)
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run_probe.py inject the probe, stream it to a log file, stay resident
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tls_check.py strict certificate check for one or more hosts
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preflight.py environment check before every experiment block (device, root,
|
||
ABI/translation, clock skew, leftover proxy/forwards, dead server)
|
||
lib_map.py what is *actually mapped* into a live process: per-library path,
|
||
base, architecture, and whether it came from the APK or was
|
||
materialized at runtime
|
||
elf_plt.py resolve a PLT stub to its imported symbol (x86_64 + aarch64) from
|
||
the relocation table; list a symbol's callers; byte-diff two
|
||
libraries and name the symbol each changed stub belongs to
|
||
apk_diff.py entry-level diff of two builds: changed / added / removed, by
|
||
content hash so same-size replacements are caught
|
||
native_crash.py locate a native death from a log or tombstone: signal, fault
|
||
address, registers, frames split app vs system, the faulting
|
||
instruction, and a flag when the fault looks *arranged*
|
||
blob_decode.py search, don't guess, the framing of a stored value
|
||
(base64/hex x rotation x deflate); re-encode the edited payload
|
||
snap.py bounded burst screenshots + control-tree capture with a stall
|
||
detector, and a verdict on whether the tree is usable at all
|
||
sig_probe.py find the exact signatures[0].toCharsString() value — offline
|
||
candidates from an APK, or the authoritative read from a device
|
||
spawn_patch_detach.py spawn under a Frida probe, detach, then launch and capture: under
|
||
spawn mode the Activity stack often never comes up, and memory
|
||
writes survive detach while hooks do not
|
||
hook_patch_only.js the minimal probe for spawn_patch_detach.py — neutralise one native
|
||
death site by offset and report PATCHED
|
||
dex_dump_validate.py dedupe, validate and rank a directory of dumped dex images: sha256
|
||
grouping, header integrity, the trivial-body ratio that separates a real
|
||
dump from an extraction-shell skeleton, and a most-likely-original ranking
|
||
(--trim for page-aligned /proc/<pid>/mem captures)
|
||
dex_mem_scan.py search memory captures for embedded dex images and extract each at the
|
||
size its own header declares -- for a decrypted dex sitting in an
|
||
anonymous mapping no maps entry names
|
||
lsposed_scaffold.py generate a minimal LSPosed/Xposed module project (manifest with the
|
||
xposed meta-data, assets/xposed_init, hook class, gradle-free build notes)
|
||
frida_rpc_serve.py bridge a Frida script's rpc.exports to a local caller with reconnect
|
||
handling, so a live native function can be called rather than reversed
|
||
rpc_template.js the editable companion to frida_rpc_serve.py
|
||
stalker_trace.js instruction-level tracing with Frida Stalker: configurable targets,
|
||
trigger selection, the event stream, and output-size rules
|
||
stalker_report.py reduce a stalker_trace.js log to block histograms and call sequences,
|
||
with an explicit diagnostic for the measured zero-event case
|
||
mt_mcp_probe.py probe MT Manager's on-device APK MCP (Streamable HTTP, port 8787):
|
||
JSON-RPC handshake plus the grouped tool inventory
|
||
java2c_probe.py collect the evidence that separates Java2C from an extraction shell, a
|
||
VMP and ordinary JNI sinking: native density and stub ratio from the dex,
|
||
JNI_OnLoad / dynamic registration / toolchain strings from the `.so`,
|
||
each item labelled strong/medium/weak
|
||
protobuf_decode_raw.py schema-free protobuf decode: hex / file / stdin to a JSON tree, every
|
||
length-delimited field kept as a candidate set with ties labelled rather
|
||
than guessed, plus a byte-exact re-encode to check a round trip
|
||
vmp_diff_harness.py build a labelled opcode-coverage fixture, derive a candidate private-
|
||
opcode map from an original/hardened dex pair, verify the comparison in a
|
||
closed loop, and render a restored stream as a smali skeleton
|
||
kernelsu_syscall_mask.py generate a KernelSU/APatch syscall-masking scaffold: an installable
|
||
userspace module skeleton plus KPM/LKM/eBPF kernel-side templates, each
|
||
with its version gate and an explicit unverified label
|
||
rasc_build.py build and verify rasc, the Rust ASC re-implementation:
|
||
--check what is present, --build clone plus cargo, --verify an APK
|
||
against droidasc and fail on any class-set difference
|
||
scan_leaks.py scan a repository for target identity before publishing it: bundle ids
|
||
in manifest / `pm` / `ps` contexts, serial-shaped tokens, PATs, inline
|
||
appkey assignments, literal endpoints, host user paths. Exemptions for
|
||
everything that must stay (tools, libraries, CVEs, hardening products,
|
||
public crackmes, placeholders), findings carry their context,
|
||
`--show-exempt` prints why a hit was suppressed, exit 0/1/2
|
||
svc_scan.py name the syscall behind an inline `svc` and the segment it sits in,
|
||
which decides whether a libc-level hook can observe the call at all;
|
||
`--context` shows neighbours because a byte scan also matches data
|
||
anti_detect_probe.js observer-only Frida probe (patches nothing): path/loader/thread/kill
|
||
hooks with caller module + offset, an environment self-report
|
||
(`TracerPid`, frida-named mappings), and live streaming so a sub-second
|
||
self-destructing target still yields evidence
|
||
```
|
||
|
||
The repository also carries an **executable** test layer, which is a different thing from the
|
||
evidence record: `tests/` asserts what the scripts do (unit, CLI contract, no-device
|
||
integration) and `tests/benchmark.md` records what a route did on a real target. `tests/README.md`
|
||
states the split, and `.github/workflows/ci.yml` runs the gates plus the suite.
|
||
|
||
## Install
|
||
|
||
This repository is a **skills repository**: the skill lives at `skills/apk-reverse/`, which is the
|
||
layout the `skills` CLI resolves, and it is installed by name rather than by copying a directory:
|
||
|
||
```
|
||
npx skills add newliver666/apk-reverse # install every skill in the repo
|
||
npx skills add newliver666/apk-reverse --list # list what is here, install nothing
|
||
npx skills add newliver666/apk-reverse --skill apk-reverse -y
|
||
npx skills use newliver666/apk-reverse@apk-reverse # use it once, without installing
|
||
```
|
||
|
||
The CLI symlinks the skill into your agent's skills directory by default (`--copy` makes independent
|
||
copies instead), and `-g` installs for every project rather than the current one. With one skill in
|
||
the repository, `--skill apk-reverse` is redundant today; it is written out here because it is what
|
||
selects a single skill once a second one exists.
|
||
|
||
Once installed, the agent loads `SKILL.md` when a task matches its description, and pulls in
|
||
`references/*` only as needed. No global state, no machine-specific paths, and no build step.
|
||
|
||
## Requirements
|
||
|
||
Nothing is mandatory; each script checks what it needs. `skills/apk-reverse/scripts/doctor.py` reports
|
||
which of these are present here, which scripts can therefore run, and — usefully — which tools exist
|
||
somewhere other than PATH.
|
||
|
||
If your toolchain lives outside PATH (a project-local `tools/` directory, a versioned SDK folder, a
|
||
runnable `.jar` instead of a command), set `APKREV_TOOLS` to one or more directories and `doctor.py`
|
||
will find them:
|
||
|
||
```
|
||
set APKREV_TOOLS=<dir>;<dir> # Windows, e.g. an SDK or project-local tools dir
|
||
export APKREV_TOOLS=<dir>:<dir> # POSIX
|
||
```
|
||
|
||
The scripts themselves are plain `python3` and are intended to work identically on Windows, macOS and
|
||
Linux; where a snippet is POSIX-only it is labelled. Nothing here assumes a Unix shell.
|
||
|
||
| Tool | Used for |
|
||
|---|---|
|
||
| Python 3.9+ | all scripts |
|
||
| **`droidasc`** (ASC) (**optional but strongly recommended — install this first**) | whole-APK cross-reference index: `findrefs` / `listclass` / `getclass` / `getmanifest`. One `pip install droidasc`, no JVM, no SDK, no index build. Turns "which of N thousand classes mentions this string" into a sub-second query, and it is the only route to a class whose name R8 mangled. **This is the tool an agent should reach for before any full decompile** — see `skills/apk-reverse/references/toolchain.md` §droidasc (ASC) — ask an APK "who references this?", in one query |
|
||
| `ddc` (optional but strongly recommended) | single-binary dex→Java decompiler with query subcommands (`info`, `findrefs`, `strings --with-locations`, per-class decompile). No JVM. **Reads** what ASC **locates**; also reports package identity reliably — see `skills/apk-reverse/references/toolchain.md` §ddc — dex-to-Java with query subcommands (worth adopting) |
|
||
| `baksmali` / `smali` + `dexlib2` jars | disassembly, assembly, surgical patching |
|
||
| JDK (`javac`, `java`) | building/running the dexlib2 patcher; also provides `keytool`/`jarsigner` |
|
||
| Android SDK build-tools (`aapt`, `zipalign`, `apksigner`) | manifest info, alignment, signing. **`apksigner` is the signer to use** — `jarsigner` rewrites the archive and breaks the alignment Android R+ requires |
|
||
| `uber-apk-signer` (optional) | one-step align + sign |
|
||
| ADB | device work |
|
||
| Frida (host package + matching on-device server) | dynamic analysis |
|
||
| a rooted device or emulator | anything beyond static analysis |
|
||
|
||
None of these need to be on `PATH`: every script accepts an explicit path for the
|
||
tools it shells out to, and `skills/apk-reverse/references/toolchain.md` covers finding
|
||
an install that `PATH` does not know about (the common case for `apksigner` and
|
||
`keytool`).
|
||
|
||
## Read this first
|
||
|
||
**This project is published for learning, research and authorized security testing only.** It ships
|
||
no exploit payloads, no target data and no third-party binaries — it is a method, a set of scripts
|
||
and an evidence record. You are responsible for having the right to analyze whatever you point it at;
|
||
see **Disclaimer** at the end of this file.
|
||
|
||
`skills/apk-reverse/references/pitfalls.md`. It is the most valuable file here — every entry is a
|
||
failure that produced a broken artifact while looking completely healthy.
|
||
|
||
The four that hurt most:
|
||
|
||
1. Stripping the whole `META-INF/` during a repack deletes ServiceLoader registrations
|
||
and the app dies at startup with an error that names an unrelated library.
|
||
2. Patching a byte-level string without preserving `string_ids` ordering gets the whole
|
||
dex rejected, while checksums and signatures verify perfectly.
|
||
3. Rebuilding a dex with a whole-tree smali round-trip damages R8 output invisibly —
|
||
class tables compare clean, and it only blows up at runtime.
|
||
4. Neutralising a native terminate path by making it **not return**. A spinning stub does not
|
||
suppress the check; it freezes the caller and every thread behind it. The app hangs with *no
|
||
crash record at all*, and the eventual death gets blamed on whatever killed the frozen process.
|
||
|
||
## Scope
|
||
|
||
Built for working on your own applications, on samples you are authorized to analyze,
|
||
and in CTF/competition sandboxes. It contains no vendored third-party binaries and no
|
||
target-specific data.
|
||
|
||
What it covers, and what it deliberately does not, is stated at the top of `SKILL.md`
|
||
under **Coverage**. The short version: Android only (no iOS), and deep on the layers
|
||
that have been worked through for real — dex patching, repacking, packers and custom
|
||
loaders, native tamper response, and Flutter/Dart AOT. An extension pass added a second
|
||
tier of documented routes: **module-side delivery** when a repack is blocked,
|
||
**extraction-shell recovery** and its VMP boundary, **emulation and live RPC** for
|
||
calling rather than reading, **instruction-level tracing** against OLLVM, **protocol
|
||
reversing** beyond REST, the **kernel-side route** map for when userspace hooking is
|
||
provably out of reach, and **on-device tooling**. A **benchmark pass** then put public
|
||
targets under those routes (`tests/benchmark.md`): it added **Java2C discrimination** (the
|
||
misdiagnosis that sends an agent hunting a decrypted DEX that never exists), **split APK /
|
||
App Bundle handling**, **schema-free protobuf decoding**, a **Dex-VMP differential** harness,
|
||
and **kernel-module templates with their version gates** — and it corrected two earlier claims
|
||
whose measurements disagreed with them. Unity/IL2CPP logic recovery,
|
||
React Native/Hermes bytecode internals, and defeating a server-side authority are **not**
|
||
covered, and the skill is written to say so and stop rather than apply the nearest
|
||
documented procedure to a target it was not written for.
|
||
|
||
Four qualifications that the Coverage section states in full and that belong here too:
|
||
|
||
- **Flutter/Dart AOT analysis has a dependency.** The workflow begins at a pool listing
|
||
(`pp.txt`-class output). Producing that needs a snapshot-decoding decompiler — aotopsy (a static
|
||
binary, no toolchain) or blutter (built from source, ~80 s) — and this repository does not contain
|
||
one. It is named as a prerequisite rather than left implicit.
|
||
- **Not every claim in this repository has a run behind it.** `docs/tool-verification/` records
|
||
what was actually measured, on which target, and with which independent cross-check; anything not
|
||
covered there is documented from experience and should be read as *inferred*, per this skill's own
|
||
claim ladder.
|
||
- **The extension pass is recorded separately and is mostly *inferred*.** Its evidence lives in
|
||
`docs/tool-verification/EXTENSION-*.md`, one file per topic, with its own strength note. The
|
||
common shape there is *the tool was measured, the route was not* — so read those files before
|
||
treating any of the newer documents as a verified path.
|
||
- **The benchmark pass is recorded per row, with that row's own strength.** `tests/benchmark.md`
|
||
names each public target, the scripts the row exercises, what actually happened (including the
|
||
rows that failed and the rows nobody ran), and how strong the evidence is. Rows marked
|
||
`unverified` are statements about the evidence in this repository, not about the mechanism.
|
||
|
||
## Repository maintenance
|
||
|
||
Four tools live at the root and are not part of the installed skill:
|
||
|
||
```
|
||
check_repo.py every skill discovered, frontmatter valid, scripts runnable,
|
||
documented paths resolve, README paths explicit and existing,
|
||
and -- on the tracked surface only -- no target identity
|
||
(delegates the rules to skills/apk-reverse/scripts/scan_leaks.py
|
||
so there is one place to argue with the exemption list)
|
||
check_refs.py every cross-reference that names a section of another
|
||
document reaches a real heading in that document
|
||
check_routing.py the on-demand inventory still matches the entry point: the
|
||
symptom mirror agrees with SKILL.md, every reference file is
|
||
named in skills/apk-reverse/references/routing.md, and every
|
||
script is too
|
||
check_commands.py every command a document tells you to run is checked against
|
||
the script's own argparse table -- a documented flag that does
|
||
not exist is a drift the anchor checks cannot see
|
||
check_budget.py keep the always-loaded part from creeping: SKILL.md's whole
|
||
body (index lines included, because they load too) measured in
|
||
lines and tokens, index-row length, long files with no
|
||
navigable head, and hedged rules reported as a trend
|
||
build_scripts.py audit for machine-specific leftovers (absolute paths, credentials)
|
||
```
|
||
|
||
Consistency has a natural counter-pressure -- a broken path fails loudly, and someone fixes it.
|
||
Bloat has none, which is why the third tool exists: every pass adds a reference, an index row and
|
||
a coverage claim, and without a measurement nothing in the repository notices.
|
||
|
||
`tests/benchmark.md` holds the **regression matrix**: dimension -> public target -> the scripts the
|
||
row exercises -> measured result -> strength label. It is the checklist to re-run before trusting
|
||
any claim under `docs/tool-verification/`. Samples are downloaded into `tools/_work/` and are never
|
||
committed, so each row names its public source and records the hash it was run against.
|
||
|
||
`docs/tool-verification/` is not part of the installed skill either. It is the evidence record
|
||
for one measurement pass against a real target: what each script actually did, which independent
|
||
method confirmed it, which defects were found, and which scenarios the target could not exercise.
|
||
It exists so the **Coverage** claims in `SKILL.md` can be checked against runs instead of trusted,
|
||
and so the gaps are written down where the next person will find them.
|
||
|
||
---
|
||
|
||
Proudly supported by the [LINUX DO](https://linux.do) community.
|
||
|
||
## Disclaimer
|
||
|
||
**For learning, research and authorized security testing only.** Every script, reference and
|
||
recorded result in this repository exists to explain *how* Android application analysis works, so
|
||
that practitioners can reason about the tools they already own. Nothing here is a service, a
|
||
product, or an endorsement of any particular use.
|
||
|
||
- **Authorized targets only.** Use this on applications you own or have been explicitly permitted to
|
||
analyze, on public CTF/challenge material, or in a sandbox you control. Analyzing software you have
|
||
no right to analyze may be unlawful where you live, and that determination is yours to make, not
|
||
this repository's.
|
||
- **No warranty, no fitness for any purpose.** The material is provided *as is*, without warranty of
|
||
any kind. Results are recorded as they were measured on one machine at one time; nothing here
|
||
promises that a route will work on your target, your device, your toolchain or today's app version.
|
||
- **Verify before you trust; back up before you act.** Several scripts modify artifacts (dex, APK,
|
||
`.so`, stored app data) and some operate on a rooted device. Keep your own copies, work on
|
||
duplicates, and read `SKILL.md`'s gates before running anything against something you care about.
|
||
- **Your use is your responsibility.** The authors and contributors accept no liability for any loss,
|
||
damage, legal consequence or service interruption arising from the use or misuse of this
|
||
repository, and are not affiliated with, endorsed by, or acting on behalf of any application,
|
||
vendor or platform it may be used to examine.
|
||
- **Test data is not distributed here.** Samples, dumps and device artifacts are deliberately absent
|
||
from the tree (`.gitignore` excludes them) and live only in a local, ignored workspace. Anything you
|
||
obtain to follow along is yours to keep safe and to delete when you are done with it — follow your
|
||
local rules and the terms that came with the sample. What this repository *does* publish is the
|
||
method and the evidence, with all target identity removed.
|
||
- **No affiliation.** Names of tools, libraries, hardening products and public challenge targets
|
||
appear only to make the material reusable; they belong to their respective owners and this project
|
||
is not connected to them.
|