reverse-engineering-anything/docs/guides/android/apktool-resource-analysis.md

# Apktool resource decoding

REA decodes Android resource tables and the binary manifest through the
caller's Apktool launcher. This completes the static triad for Android
targets: Java/Kotlin sources through the JADX family, engine-grade
decompilation through JEB, and resources through this family. REA never
installs Apktool or a Java runtime.

## Supply tools

Use Apktool 2.7.0 or newer (verified with 2.7.0 and 3.0.3 on Linux) and a Java runtime the
launcher can find. Select the launcher through the environment:

```sh
# Optional: absolute path to the apktool launcher (upstream wrapper or a
# java -jar script); without it, apktool resolves from PATH.
export REA_APKTOOL_COMMAND=/absolute/path/apktool
```

Readiness is `rea inspect-apktool-client`: it runs `apktool --version` and
reports the resolved launcher, its selection source, and its version. A
missing launcher reports `capability_unavailable` with the
`REA_APKTOOL_COMMAND` remediation rather than attempting an installation.
`binary_session` uses the same host probe for tool availability; it does not
validate a particular APK or guarantee that the selected input can be decoded.

Client inspection and decode results disclose the following reported-version
advisory windows without refusing otherwise compatible launchers:

| Advisory                                                                                              | Reported version window                          | Host scope |
| ----------------------------------------------------------------------------------------------------- | ------------------------------------------------ | ---------- |
| [CVE-2024-21633](https://github.com/iBotPeaches/Apktool/security/advisories/GHSA-2hqv-2xv4-5h5w)      | Before 2.9.2                                     | All        |
| [GHSA-vgwr-4w3p-xmjv](https://github.com/iBotPeaches/Apktool/security/advisories/GHSA-vgwr-4w3p-xmjv) | Before 2.9.3                                     | Windows    |
| [CVE-2026-39973](https://github.com/iBotPeaches/Apktool/security/advisories/GHSA-m8mh-x359-vm8m)      | 3.0.0 release line through versions before 3.0.2 | All        |

The 2026 advisory names 3.0.1 and its 3.0.2 fix. Inclusion of 3.0.0 is
source-derived: [tagged 3.0.0](https://github.com/iBotPeaches/Apktool/blob/f770b39e425af4fa6ac4ca1e9ea6c4824339c6d3/brut.apktool/apktool-lib/src/main/java/brut/androlib/res/table/ResTypeSpec.java)
passes type names through unchanged; the [3.0.2 patch](https://github.com/iBotPeaches/Apktool/commit/65dd8480dfcb63068562ffaa527f71bb0a9f772c)
validates those names at their owner before they reach the output-path producer.
Prereleases before the fixed release are conservatively disclosed; the exact
`-dirty` downstream marker is compared as a release while preserving its spelling.
This is version guidance, not verification of a particular prerelease or decoder.

A launcher version does not prove the decoder's contents, execution platform,
downstream backports, or overall safety. Windows applicability uses the selected
local host; an opaque wrapper may run another engine. A missing warning means
only that none of these version/host windows matched. Verify the selected
decoder's patches before decoding untrusted APKs; the compatibility floor above
is not a security recommendation. REA does not fetch advisories at runtime.

On Windows, a `.bat` or `.cmd` launcher (such as Chocolatey's `apktool.bat`)
runs through an explicit `cmd.exe /d /s /c` call. That call has no AutoRun,
no delayed expansion, and quotes every argument. A launcher path that
contains `"`, `%`, `^`, `!`, `&`, `|`, `<` or `>` is reported as
`not_configured` instead of being passed to `cmd.exe`. If REA's temporary
decode paths contain those characters, decoding through a batch launcher
reports `capability_unavailable`.

## Answer an analyst question

```sh
rea inspect-apktool-client
rea decode-android-resources /targets/Example.apk
rea decode-android-resources /targets/Example.apk --locale de
rea decode-android-resources /targets/Example.apk --locales de --locales pt-BR
rea decode-android-resources /targets/Example.apk --locales de --locales pt-BR --string-tables-only
rea decode-android-resources /targets/Example.apk --no-strings
rea decode-android-resources /targets/Example.apk --decode-timeout-ms 900000
rea decode-android-resources /targets/Example.apk --string-offset 2000 --string-limit 100 --string-tables-only
rea decode-android-resources /targets/Example.apk --max-string-table-bytes 16777216 --max-total-string-table-bytes 67108864
```

Equivalent MCP methods are `inspect_apktool_client` and
`decode_android_resources`. The decode request takes `path`, an optional
primary `locale` (project `res/values-<locale>/strings.xml` instead of the default
table), `locales` (repeatable array of additional localized string tables to project
from the same single decode pass), and `include_strings` (default true). Regional locales such as `pt-BR`
select Android's `values-pt-rBR`. A three-digit region such as `es-419`
selects `values-b+es+419`; `es-r419` is rejected because Android's legacy
`-r` form requires a two-letter region. Android qualifiers such as `pt-rBR`
and `b+zh+Hans+CN` may also be supplied directly.

Set `string_tables_only: true` (CLI `--string-tables-only`) to return string
entries only inside `string_tables`, including when selecting a single table.
The top-level `strings` array is then empty by request; it does not establish
that the primary table is empty. Table status, counts and coverage still describe
the examined source. This avoids repeating primary entries in multi-locale
responses and charges the aggregate output budget for one copy per table.
Omitting the option preserves existing responses. `include_strings: false`
still suppresses all string projection, including in this mode.

Use `string_offset` and `string_limit` (CLI `--string-offset` and
`--string-limit`) to select a page of valid parsed entries from each requested
table, in source order. Defaults are offset 0 and limit 2000. Explicit page or
budget controls include `string_tables` even for a single primary table; its
`page` gives the requested offset and limit, returned count, and `next_offset`.
Retry that offset with the same locale and confirm `target.sha256` matches.
Each call decodes a fresh owned snapshot; it does not retain a workspace or
promise identity across changed APKs. A null continuation means the page reaches
the end, while table coverage remains partial if earlier entries were omitted.
An offset at or beyond the end returns an empty, present table with known counts.
If the continuation equals the requested offset, no output entry fit: increase
`max_total_strings` or use `string_tables_only` before retrying.

`max_total_strings` (CLI `--max-total-strings`, default 10000) bounds returned
string copies across all tables. Raise it, request fewer locales, or use
`string_tables_only` when aggregate output is exhausted. The legacy
multi-table shape charges both copies of primary strings. `max_string_table_bytes`
(CLI `--max-string-table-bytes`, default 8388608) bounds one XML source read;
`max_total_string_table_bytes` (CLI `--max-total-string-table-bytes`, default 33554432) bounds XML reads across distinct physical tables. Locale aliases
share the physical read and parsed page. Raise the relevant read budget to
retry an oversized table; a larger string limit or timeout does not raise it.
These controls take nonnegative safe-integer offsets and positive safe-integer
budgets, apply on the next decode, and require no REA restart. Process memory
and response transport capacity still apply.

## Interpret the result

- **An owned APK snapshot is digested and decoded.** `target.sha256` and
  `target.bytes` bind the observation to the exact APK that was decoded.
  The Evidence subject carries the same snapshot digest and caller-selected
  path, including when the original file changes during decoding.
  A change during snapshot acquisition reports retryable `artifact_changed`;
  wait for a stable input before retrying. Host read permission failures report
  `access_denied`, while a missing or non-regular selected path reports
  `invalid_request` with the rejected `path` field.
- **Metadata comes from apktool.yml as apktool printed it.** Version codes
  keep their own spelling (`'7'` versus `7`); `package_name` is read from
  the decoded manifest, not inferred.
  The `version: 2.9.0`-or-later header that Apktool 2.9+ and 3 emit selects
  their single-line string dialect: literal hashes, single quotes, empty
  strings, and the text `null` stay part of the value; producer backslashes
  and Unicode escapes decode once. Older/tagged documents retain YAML scalar
  semantics; double-quoted values also retain YAML string semantics.
  This distinction follows the released
  [2.9.0 metadata writer](https://github.com/iBotPeaches/Apktool/blob/b64e257c9b689eb9630ad0241f2fe4f4a749955b/brut.apktool/apktool-lib/src/main/java/brut/androlib/apk/VersionInfo.java#L38-L42),
  [3.0.3 metadata writer](https://github.com/iBotPeaches/Apktool/blob/18b5e99cb56ff9451e8aa55b065dcf5bbd616975/brut.apktool/apktool-lib/src/main/java/brut/androlib/meta/VersionInfo.java#L49-L55)
  and [string escape owner](https://github.com/iBotPeaches/Apktool/blob/18b5e99cb56ff9451e8aa55b065dcf5bbd616975/brut.j.yaml/src/main/java/brut/yaml/YamlStringEscapeUtils.java#L55-L116).
- **The manifest is the decoded text**, bounded at 512 KiB and reported as
  truncated when larger.
- **Strings are projected verbatim.** Escaped entities stay escaped, and
  entries containing nested markup (`<b>`, `<xliff:g>`) are counted as
  unparsed rather than flattened — the limitation names the examined count.
  Malformed XML and a wrong document root are whole-document projection
  failures: the result is partial, the failure reason is disclosed, and entry
  counts remain unknown. They are not counted as one unsupported string.
  The default page returns up to 2000 entries with partial coverage when more
  exist; its limitation names the next `string_offset`. `locales` lists observed regular `strings.xml` tables whose exact
  `values-<locale>` directory is selectable by the request's locale grammar.
  Locale suffixes allow up to 23 ASCII characters, derived from Apktool's
  language, script, region, and variant fields; for example,
  `b+sr+Latn+RS+REVISED` selects that exact table.
  Other table directories, including combined qualifiers such as
  `values-en-rUS-v21` and `values-mcc310-fr`, are named in limitations with
  their source spelling. They are not advertised as selectable locales;
  REA does not infer Android's runtime resource matching. Non-regular
  strings-table paths are disclosed with partial coverage. Discovery uses
  the same bounded traversal as the file count; filesystem failures remain
  failures rather than being interpreted as missing tables.
  When multiple tables are requested with `locales`, `string_tables` records
  each projected table with its locale, status (`present`, `missing`,
  `oversized`, `malformed`, or `skipped`), entry counts, and coverage,
  with default aggregate budgets of 10,000 strings and 32 MiB XML. When `locales`
  is omitted, `string_tables_only` is not true and no string page or budget
  control is selected, legacy single-table payloads are preserved without adding
  `string_tables`.
- **Smali is skipped by design** (`apktool d --no-src`): Java-source
  recovery belongs to the JADX family. Resource smali edits and rebuild are
  a follow-up lane with mutation authority.
- **Workspaces are owned and short-lived.** Decoding happens in a
  provider-owned temporary directory that is removed before the result is
  returned. The APK snapshot and framework cache both live inside this directory.
  If removal fails, the result names the residual path and the provider retains
  ownership for a cleanup retry on close, including failed decodes.

## Resource and lifecycle limits

- The decode wall clock is `decode_timeout_ms` (CLI `--decode-timeout-ms`).
  Omitted means 600000 ms. The integer range is 1 to 2147483647. A change
  applies on the next decode. It does not raise the 4194304-byte (4 MiB)
  output capture budget. That capture budget has no runtime override. A
  stopped decode reports `provider_timeout` and names the effective
  milliseconds; an exceeded capture budget reports `resource_constraint`.
- The version probe waits 20000 ms and retains 65536 bytes. This release has
  no runtime override for that probe. `decode_timeout_ms` does not raise it.
- Manifest reads are bounded to 512 KiB before decoding UTF-8. Strings XML
  reads default to 8 MiB per table; larger documents are skipped with partial
  coverage and an explicit read-budget recovery, rather than reported as missing.
- `decoded_file_count` is capped at 100,000 files; the cap is reported in
  the limitations when hit.
- An ordinary nonzero decode exit surfaces as `unsupported_target` naming
  the caller-selected APK, with Apktool's diagnostic and captured output.
  Launcher startup, ownership preparation, signal termination and incomplete
  output collection remain provider failures; they do not establish that the
  selected APK is unsupported.

## Real verification

`npm run verify:apktool -- --apk PATH` exercises both operations against a
real launcher. Record: apktool 2.7.0-dirty (Debian packaging) on Linux with
OpenJDK 25 against a signed aapt2-built probe APK carrying two resource
locales — launcher version, on-disk digest agreement, apktool.yml metadata
(1.2.3, SDK 24–34), manifest package agreement, default and `de` string
tables projected. Parser goldens in the test suite come from the same
decode. See `docs/development/testing.md` for the lane summary.

Multi-locale and table-only projection were also verified through real CLI and
stdio MCP workflows on Linux with Apktool 3.0.3/JDK 21 against NewPipe 0.29.1,
ApiDemos 6.0.18 and Appium Settings 8.2.1. Independent XML projection checks,
exact facts/Evidence parity and bounded task costs are recorded in the
[shared-decode and table-only checkpoint](https://github.com/morluto/rea/blob/42e1a17d6e6c0487f17be0bae248553c4caba7f7/experiments/analysis-efficiency/apktool-string-tables.md).
This qualifies selected resource facts, not application execution or independent
binary resource-decoder completeness.

If the selected APK changes while its private snapshot is copied, acquisition
returns `artifact_changed`; request-schema correction cannot recover a stable
snapshot. Launcher spawn permission denial is distinct from a missing launcher,
and configuration diagnostics retain the selected command and system error.