Agent skill

Bypassing Mobile Pinning

by trilwu in trilwu/secskills

Diagnose and defeat TLS interception failures in mobile apps — certificate pinning, Android Network Security Config, user-CA distrust, native BoringSSL pinning, and mutual TLS — using objection…

MITAuto-check passedSecurity

Install Bypassing Mobile Pinning

skills CLI
$ npx skills add trilwu/secskills --skill bypassing-mobile-pinning -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install trilwu/secskills bypassing-mobile-pinning --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/trilwu/secskills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/secskills-offense/skills/bypassing-mobile-pinning .claude/skills/bypassing-mobile-pinning && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
bypassing-mobile-pinning
GitHub stars
157
Token cost
~2.5k tokens
SKILL.md length
1,020 words
Files
1
Skills in repo
50
Repo updated
First seen
Licence
MIT

At a glance

Diagnose and defeat TLS interception failures in mobile apps — certificate pinning, Android Network Security Config, user-CA distrust, native BoringSSL pinning, and mutual TLS — using objection…

  • Works in 6 steps: The app never used your proxy. Some… → Certificate Transparency enforcement.… → Mutual TLS. The server demands a client… → …
  • Charles shows a TLS handshake error
  • SKILL.md covers When to Use, When NOT to Use, Diagnose First and Android: Hook by Stack, plus 5 more sections
  • Calls adb, rg and openssl

What it does

Bypassing Mobile Pinning is an agent skill from trilwu/secskills. Diagnose and defeat TLS interception failures in mobile apps — certificate pinning, Android Network Security Config, user-CA distrust, native BoringSSL pinning, and mutual TLS — using objection, Frida, SSL Kill Switch, and APK patching. Use when Burp, mitmproxy, or Charles shows a TLS handshake error, an empty proxy, or "network error" from a mobile app, or when a target is known to pin certificates.

Its SKILL.md is about 2.5k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Security, covering Network security and Mobile application security. It works with Android, Frida and Flutter. The repository describes itself as: Transform Claude Code into your personal security engineer. The licence is MIT.

When your agent uses it

  • Charles shows a TLS handshake error
  • Network error from a mobile app
  • A target is known to pin certificates

Example prompts

  • “network error”
  • “/bypassing-mobile-pinning”

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

  1. The app never used your proxy. Some stacks ignore system proxy settings
  2. Certificate Transparency enforcement. Some SDKs require SCTs; your CA
  3. Mutual TLS. The server demands a client certificate. Extract the .p12
  4. Root/jailbreak or Frida detection. The app detects instrumentation and
  5. The traffic is not HTTP. WebSockets, gRPC, MQTT, or a custom protocol
  6. Pinning applied only to specific hosts. Analytics flows fine while the

What it can do on your machine

Read from SKILL.md and the folder at commit ca53957. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • adb
    • rg
    • openssl

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Bypassing Mobile Pinning loads about 2.5k tokens when it runs. Until then it costs about 107 tokens; SKILL.md has 1,020 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~107
When it runs · the whole SKILL.md, loaded when a task matches
~2.5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from trilwu/secskills at commit ca53957, republished under its MIT licence (© trilwu). 1,020 words, ~2,544 tokens.

Download SKILL.mdSave it as .claude/skills/bypassing-mobile-pinning/SKILL.md (or your agent's skills folder).
name
bypassing-mobile-pinning
description
Diagnose and defeat TLS interception failures in mobile apps — certificate pinning, Android Network Security Config, user-CA distrust, native BoringSSL pinning, and mutual TLS — using objection, Frida, SSL Kill Switch, and APK patching. Use when Burp, mitmproxy, or Charles shows a TLS handshake error, an empty proxy, or "network error" from a mobile app, or when a target is known to pin certificates.
verified
2026-07-27

Bypassing Mobile Pinning

Most time lost here is spent bypassing pinning that was never there. An empty proxy has at least six causes, and the fix for each is different — one of them is not pinning at all but Android's default distrust of user CAs, and another is that the app has its own TLS stack and never saw your proxy. Diagnose before you reach for a bypass script.

Use only against apps you are authorized to test.

When to Use

  • Burp/mitmproxy/Charles shows a TLS handshake failure from a mobile app
  • The proxy shows nothing while the app clearly reaches the network
  • The app reports "network error", "connection insecure", or similar with the proxy configured
  • You know the target pins, and need the right hook for its stack

When NOT to Use

  • Flutter targets — use reversing-flutter-apps; Flutter's failure looks identical but the cause and fix are specific to its engine
  • The wider mobile assessment — use testing-mobile-applications
  • The backend once traffic is visible — use testing-apis
  • Reversing a native .so in depth — use analyzing-binaries

Diagnose First

Run this before installing anything. The symptom tells you the cause.

SymptomLikely causeFix
Proxy sees the CONNECT, then TLS alert unknown_ca / bad_certificateYour CA is not trustedInstall as system CA, or patch Network Security Config
Proxy sees the CONNECT, then alert only for some domainsReal pinning, scoped to those hostsHook the pinning check
Proxy sees nothing at all, app worksApp ignores the system proxyForce traffic at the network layer (Flutter, gRPC, some SDKs)
Proxy sees the handshake, server rejects the clientMutual TLS — the app presents a client certificateExtract the client cert; this is not pinning
Works on emulator, fails on device (or vice versa)Root/emulator detection, not TLSDifferent problem — see the detection section
Fails only after loginPinning applied to the API host onlyHook, then re-check
bash
# What does the app actually declare?
apktool d target.apk -o out
cat out/res/xml/network_security_config.xml 2>/dev/null
rg -n 'networkSecurityConfig|usesCleartextTraffic' out/AndroidManifest.xml

# Which TLS stack is in play?
rg -l 'okhttp3|CertificatePinner|TrustKit|AFNetworking|Alamofire' out/ 2>/dev/null | head
unzip -l target.apk | rg 'libssl|libcrypto|libconscrypt|libflutter|libil2cpp|libmonodroid'

Check Network Security Config before assuming pinning. Since Android 7, apps do not trust user-installed CAs by default. An app with no pinning code at all will still fail interception. Two fixes:

bash
# A. Install your CA as a SYSTEM certificate (no app modification — preferred)
#    Emulator:
emulator -avd <name> -writable-system
adb root && adb remount
openssl x509 -inform PEM -subject_hash_old -in burp.pem | head -1   # → e.g. 9a5ba580
cp burp.pem 9a5ba580.0 && adb push 9a5ba580.0 /system/etc/security/cacerts/
adb shell chmod 644 /system/etc/security/cacerts/9a5ba580.0
#    Rooted device: use a Magisk module so the change survives reboot

# B. Patch the config and repack (when you cannot get a system CA)
#    Add to network_security_config.xml:
#      <base-config><trust-anchors>
#        <certificates src="system"/><certificates src="user"/>
#      </trust-anchors></base-config>
apktool b out -o patched.apk && apksigner sign --ks debug.keystore patched.apk

Option A is better: it modifies nothing in the app, so integrity checks, signature checks, and Play Integrity are unaffected. Reach for B only when you cannot get a system CA onto the device.

Android: Hook by Stack

Identify the stack, then hook it. A generic script that misses will look like "the bypass failed" when it simply targeted the wrong layer.

bash
# Start here — covers the common Java-layer stacks in one shot
objection -g com.target.app explore
# then: android sslpinning disable

# Or a maintained universal script
frida -U -f com.target.app -l android-ssl-bypass.js --no-pause
StackMarkerHook point
OkHttp 3/4okhttp3.CertificatePinnerCertificatePinner.check() — return normally
HttpURLConnectionjavax.net.ssl.*Custom X509TrustManager.checkServerTrusted()
Conscryptlibconscrypt_jni.soPlatform.checkServerTrusted, or the native layer
Apache HttpClientorg.apache.httpSSLSocketFactory verifier
WebViewonReceivedSslErrorForce handler.proceed()
Native / BoringSSLlibssl.so, custom .soSSL_CTX_set_custom_verify, ssl_verify_peer_cert
Xamarinlibmonodroid.so, libxamarin*Mono-level ServicePointManager / HttpClientHandler
Unitylibil2cpp.soUnityWebRequest cert handler, or BestHTTP's verifier
gRPClibgrpc.soChannel credentials; often also ignores the proxy

Native pinning is where the universal scripts stop working. When objection reports success but traffic still fails, the check is in a .so. BoringSSL's verification entry points are not exported, so scripts locate them by pattern scanning — and the pattern is version-specific. Confirm what you are dealing with:

bash
# Is a native TLS stack even present?
unzip -j target.apk 'lib/arm64-v8a/*' -d libs && rg -l 'SSL_|BoringSSL|s2n' libs/
# Trace the native calls to see which library terminates TLS
frida-trace -U -f com.target.app -i 'SSL_*' -i '*verify*'

For Unity, Xamarin, and Flutter builds, recover symbols first — reversing-unity-il2cpp, reversing-flutter-apps — then hook the named function rather than pattern-scanning blind.

iOS

bash
# Frida-based, covers NSURLSession and the common libraries
objection -g com.target.app explore
# then: ios sslpinning disable

# Jailbroken device, no Frida
# SSL Kill Switch 3 — system-wide, survives app updates
LibraryHook point
NSURLSession (default)URLSession:didReceiveChallenge: → .useCredential with the server trust
TrustKitTSKPinningValidator result
AFNetworkingAFSecurityPolicy.evaluateServerTrust:
AlamofireServerTrustManager / ServerTrustEvaluating
Native/BoringSSLSame as Android — hook the verify callback

Non-jailbroken devices: repackage the IPA with the Frida gadget (objection patchipa), re-sign, and sideload. Expect this to trip integrity or attestation checks in hardened apps.

Show full SKILL.md (452 more words)Show less

When It Still Fails

Work through these in order rather than trying more bypass scripts.

  1. The app never used your proxy. Some stacks ignore system proxy settings entirely. Force traffic: transparent redirect with iptables, or a VPN/tun-based proxy.
    bash
    adb shell su -c 'iptables -t nat -A OUTPUT -p tcp --dport 443 -j DNAT --to <proxy>:8080'
  2. Certificate Transparency enforcement. Some SDKs require SCTs; your CA has none. Look for CT libraries and hook the CT verifier specifically.
  3. Mutual TLS. The server demands a client certificate. Extract the .p12 or keystore from the app bundle, recover its password (often in code or strings), and load it into your proxy's client-certificate settings. This is a separate mechanism from pinning and no pinning bypass will touch it.
  4. Root/jailbreak or Frida detection. The app detects instrumentation and fails closed, which looks like a TLS problem. Check for a frida string scan, port 27042 probing, /proc/self/maps inspection, or Play Integrity. Bypass the detection first, then retry the pinning bypass.
  5. The traffic is not HTTP. WebSockets, gRPC, MQTT, or a custom protocol over TLS. Your HTTP proxy will not show it — capture at the socket layer or with a protocol-aware proxy.
  6. Pinning applied only to specific hosts. Analytics flows fine while the API fails. Confirm by comparing which hosts appear in the proxy.

Verify You Actually Won

A bypass is confirmed when you can see and modify a request end to end — not when the app merely stops erroring.

1. Proxy shows the API host, not just analytics and CDN traffic
2. Request and response bodies are readable
3. A modified request produces a different server response
4. Authenticated flows still work through the proxy

If only step 1 passes, you may be seeing a fallback path while the real API traffic goes elsewhere.

Rationalizations to Reject

  • "The bypass failed, the app must use strong pinning." Six causes, one of which is pinning. Diagnose from the symptom table.
  • "I installed the CA, so TLS should work." As a user certificate, on Android 7+, for an app that does not opt in — it will not.
  • "objection said pinning disabled." It disabled the Java-layer checks it knows. Native pinning is untouched.
  • "No traffic in the proxy means the app is offline." It means the app is not using your proxy.
  • "I'll just patch the APK." Repacking breaks signatures and trips integrity checks. Prefer a system CA and runtime hooks; patch as a last resort.
  • "Pinning bypassed, assessment done." Bypassing pinning is setup, not a finding. Pinning is a defense-in-depth control, and its absence is a low severity note — the findings are in the API behind it.

References

  • testing-mobile-applications — the wider assessment this unblocks
  • reversing-flutter-apps — Flutter's separate TLS stack and proxy behaviour
  • reversing-unity-il2cpp, reversing-react-native-apps — symbol recovery before hooking framework-specific stacks
  • testing-apis — where the actual findings are, once you can see the traffic
  • objection, Frida, SSL Kill Switch 3, apktool, apksigner, Magisk

© trilwu, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in secskills-offense/skills/bypassing-mobile-pinning of trilwu/secskills.

Open the folder on GitHubat commit ca53957

Compare with similar skills

Bypassing Mobile Pinning next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Bypassing Mobile Pinning compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Bypassing Mobile Pinning this skilltrilwu/secskills157—~2.5kAutomated safety check: PassMIT
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Mobile App Security Testinglangbyyi/CyberStrikeAI-SRC129—~12kAutomated safety check: PassApache-2.0
Frida Mobile Securityindex-login/MobileRE-Skill158—~3kAutomated safety check: PassMIT
Mira Risk Collectvw2x/Mira105—~793Automated safety check: PassGPL-3.0
Rev Dex Dumperindex-login/MobileRE-Skill158—~1.9kAutomated safety check: PassMIT

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Categories

Questions about Bypassing Mobile Pinning

What does Bypassing Mobile Pinning do?

Diagnose and defeat TLS interception failures in mobile apps — certificate pinning, Android Network Security Config, user-CA distrust, native BoringSSL pinning, and mutual TLS — using objection…. Bypassing Mobile Pinning is an agent skill from trilwu/secskills. Diagnose and defeat TLS interception failures in mobile apps — certificate pinning, Android Network Security Config, user-CA distrust, native BoringSSL pinning, and mutual TLS — using objection, Frida, SSL Kill Switch, and APK patching.

When should I use Bypassing Mobile Pinning?

Bypassing Mobile Pinning fits situations like: charles shows a TLS handshake error; network error from a mobile app; A target is known to pin certificates.

How do I install Bypassing Mobile Pinning in Claude Code?

Run `npx skills add trilwu/secskills --skill bypassing-mobile-pinning -a claude-code`. Or copy the skill folder (secskills-offense/skills/bypassing-mobile-pinning in trilwu/secskills) into .claude/skills/bypassing-mobile-pinning in your project. Claude Code loads it when a task matches its description.

How do I install Bypassing Mobile Pinning in Codex?

Run `npx skills add trilwu/secskills --skill bypassing-mobile-pinning -a codex`. Or copy the skill folder (secskills-offense/skills/bypassing-mobile-pinning in trilwu/secskills) into .agents/skills/bypassing-mobile-pinning in your project. Codex loads it when a task matches its description.

Can I use Bypassing Mobile Pinning in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add trilwu/secskills --skill bypassing-mobile-pinning -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/bypassing-mobile-pinning, .gemini/skills/bypassing-mobile-pinning, .github/skills/bypassing-mobile-pinning and .opencode/skills/bypassing-mobile-pinning in your project.

What does Bypassing Mobile Pinning need to run?

Going by SKILL.md and its folder, Bypassing Mobile Pinning needs the command-line tools its instructions call (adb, rg and openssl).

Does Bypassing Mobile Pinning access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Bypassing Mobile Pinning safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Bypassing Mobile Pinning use?

Bypassing Mobile Pinning is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Bypassing Mobile Pinning use?

About 2.5k tokens (SKILL.md is roughly 10k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Bypassing Mobile Pinning?

Skills that share tags, products or a category with Bypassing Mobile Pinning: Mobile Security (transilienceai/communitytools, 563 stars), Mobile App Security Testing (langbyyi/CyberStrikeAI-SRC, 129 stars), Frida Mobile Security (index-login/MobileRE-Skill, 158 stars) and Mira Risk Collect (vw2x/Mira, 105 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Bypassing Mobile Pinning?

trilwu (a GitHub user) maintains it in trilwu/secskills, which has 157 GitHub stars. The repository holds 50 skills in this directory. The repository was last updated on September 4, 2026.

Source: trilwu/secskills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.