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reverse-engineering-anything/docs/index.md
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8bc01b48b4 feat(native): list ELF and Mach-O initializer and finalizer functions (#9574)
* feat(native): list ELF and Mach-O initializer and finalizer functions

inspect_native_initializers and inspect-native-initializers list the
functions an ELF or Mach-O image runs before and after main: ELF
DT_INIT, DT_FINI, preinit, init and fini arrays and .ctors/.dtors, and
Mach-O __mod_init_func, __mod_term_func and __init_offsets, with slot
addresses, resolved targets, symbols where available and relocation
facts for relocatable objects. Nothing is executed. Slot, symbol,
relocation and note budgets are shared across tables, sentinels are
matched at the image width, and target-derived names are bounded and
marked untrusted.

* fix(native): keep ELF initializer slots unresolved when relocation coverage is partial

A skipped, unreadable or over-budget section relocation table now keeps
every slot it could reach unresolved instead of reading the stored word as
raw or dropping a .ctors slot as a sentinel. Dynamic writes that only
partly overlap a slot, or write it twice, leave it unresolved. Linked
images no longer reapply retained non-SHF_ALLOC link-time records.

The dynamic relocation walk now pauses at the shared reader's step
boundaries and observes cancellation there, resolved targets need only
their first byte mapped, and unreadable symbol names make the report
incomplete.

* fix(native): stop reporting unchecked Mach-O initializer words as resolved

Object files now apply their own section relocations: an UNSIGNED entry
against a defined symbol gives symbol_addend, one against an undefined
symbol gives unresolved_import, and any other entry leaves the slot
unresolved. Linked images without a fixup decoder, such as 32-bit ones,
keep pointer slots unresolved when an LC_DYLD_INFO bind stream or
LC_DYSYMTAB external relocations could replace the stored word.

LC_DYLD_INFO rebases now report dyld_info_rebase instead of
chained_fixup, and unreadable symbol names make the report incomplete.
Section headers keep their declared reloff and nreloc for this.

* docs(native): move initializer guide under docs/guides/native

The documentation guide assigns analyst workflows to docs/guides/<domain>/.
Move the guide there, place its navigation and directory entries in the
Native binaries group, and update links from the docs index, CLI guide,
spec and authored skill. The public /native-initializers route is
unchanged.

The guide and spec also describe per-slot relocation coverage, retained
link-time records, Mach-O object relocations, undecoded bind streams,
the dyld_info_rebase resolution and unreadable names.

* fix(native): keep IFUNC and partly relocated ELF initializer slots unresolved

An absolute relocation against an STT_GNU_IFUNC symbol no longer reports
the resolver address as the target. Section relocation records now use
their real write width, so a record that writes only part of a slot,
starts inside it or repeats it leaves the slot unresolved instead of
reading a raw zero or dropping a .ctors slot as a sentinel.

On 32-bit ARM the Thumb bit is cleared when locating a target's section
and file offset, while value_va keeps the stored callable value.

* fix(native): locate Thumb Mach-O initializer targets and reject arm64_32 with a 64-bit header

On CPU_TYPE_ARM the Thumb bit is cleared when locating and naming a
target, since nlist values do not carry it. An arm64_32 image that
declares a 64-bit header is rejected as malformed rather than read with
8-byte slots. The guide and spec describe IFUNC relocations, partly
relocated section slots, Thumb targets and this rejection.

* fix(native): index initializer address lookups and keep ambiguous mappings unknown

ELF and Mach-O initializer lookups now build the shared file mapping
index once per image, so each slot and target lookup is logarithmic in
the number of load segments rather than a scan of every mapping.

An address that load segments map ambiguously no longer falls back to a
section header offset. Its file offset is reported as unknown and the
report is incomplete; only genuinely unmapped spans use the section
fallback.

* fix(native): report Mach-O bind names over the name budget

A bound import name longer than the 1024-byte name budget was dropped
without a trace, although it is the only identity of an unresolved
initializer target. It now counts toward the over-long name limitation
and makes the report incomplete.

* test(native): count mapping lookups instead of timing the load index regression

The load-mapping regression asserted a wall-clock bound, which is
sensitive to machine load. It now spies on the shared mapping module and
requires the same number of mapping scans and index builds for 8 and 64
slots, so a per-slot scan of every load segment fails deterministically
on a small fixture.

* fix(native): yield while decoding legacy rebase runs

* fix(native): preserve initializer mapping and coverage

* fix(native): index legacy fixup spans

* fix(native): preserve relocation uncertainty and bound bind lookup work

* fix(native): validate ELF slot mappings and yield section relocation scans

---------

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: morluto <76467478+morluto@users.noreply.github.com>
2026-11-09 08:58:12 -05:00

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REA Reverse Engineer Anything Understand binaries, applications, and runtime behavior with one CLI and MCP server.
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Investigate with your agent Connect REA to your coding agent, describe the app or feature you want to understand, and follow the evidence. /mcp-prompts
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Inspect across formats Explore native binaries, JavaScript and Electron apps, .NET assemblies, Android packages, firmware, and websites. /installation
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Start with one command

npx rea-agents setup

Choose your agent, review the planned changes, and approve setup. Native binary analysis can use an existing Hopper, Ghidra, or IDA installation; static JavaScript analysis needs no native analysis engine.

For a first result from an extracted JavaScript application or ASAR:

npx -y rea-agents@latest analyze-javascript-application /absolute/path/to/app --json

See installation and setup for requirements and configuration.

For runtime instrumentation, see the Frida guide.

Choose a guide

The documentation directory lists every guide by domain.

Task Guides
Identify a desktop installation Runtime candidates, evidence and follow-up files
Inspect native functions, references, or types Native binaries, Go metadata, Rust dependencies, CPython pyc files, PE certificates, PE imports, PE TLS/load config, ELF notes, initializer functions, ELF unwind ranges, Linux kernel modules, Linux kernel build config, Apple IPS, Erlang BEAM, offline ELF layout, recorded crashes
Select a native provider or import format Ghidra semantics, Windows, DOS, raw bytes, GameCube DOL, MIPS, RISC-V, PowerPC, PSP, NativeAOT, IDA, Kuna, JEB
Analyze JavaScript or Electron artifacts Static analysis, tracing and comparisons, application graph, source recovery
Compare static JavaScript with runtime observations Runtime attribution, reconciliation, Electron observation, Electron fuses
Inspect assemblies, packages, or firmware Godot PCK, UnityFS, wxapkg, U-Boot uImage, .NET, Python packages, Android, APK signatures, Apktool resources, ADB acquisition, Apple, Harmony, firmware, Device Tree, FIT images, UF2/DfuSe, Flutter, ESP images, ESP flash images, WASM, EVM
Observe or compare a browser scenario CDP observation, scenarios, runtime evidence, historical captures
Serve recorded behavior as an agent environment Agent environments
Trace captured website source Source locations, module traces, script export
Capture and compare a command Process capture
Use CLI/MCP and retain evidence CLI, MCP contracts, agent prompts, obligation ledgers

For development, use testing, client verification, tool design, admission limits and recovery, and releasing. Reconstruction readiness describes a development conformance verifier. The 6.2 migration records that release's compatibility changes; the roadmap tracks future work.

REA inspecting a native binary in Hopper