What it does. 'Bypasses SSL/TLS certificate pinning implementations in Android and Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill performing-mobile-app-certificate-pinning-bypass, or copy the skill folder into ~/.claude/skills/performing-mobile-app-certificate-pinning-bypass/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/performing-mobile-app-certificate-pinning-bypass/SKILL.md

SKILL.md (verbatim)

name: performing-mobile-app-certificate-pinning-bypass
description: 'Bypasses SSL/TLS certificate pinning implementations in Android and
  iOS applications to enable traffic interception during authorized security assessments.
  Covers OkHttp, TrustManager, NSURLSession, and third-party pinning library bypass
  techniques using Frida, Objection, and custom scripts. Activates for requests involving
  certificate pinning bypass, SSL pinning defeat, mobile TLS interception, or proxy-resistant
  app testing.

  '
domain: cybersecurity
subdomain: mobile-security
author: mahipal
tags:
- mobile-security
- android
- ios
- certificate-pinning
- frida
- penetration-testing
version: 1.0.0
license: Apache-2.0
nist_csf:
- PR.PS-01
- PR.AA-05
- ID.RA-01
- DE.CM-09
mitre_attack:
- T1059
- T1056
- T1036
- T1078
- T1027

Performing Mobile App Certificate Pinning Bypass

When to Use

Use this skill when:

• Mobile app refuses connections through a proxy due to certificate pinning
• Performing authorized security testing requiring HTTPS traffic interception
• Assessing the strength and bypass difficulty of pinning implementations
• Evaluating defense-in-depth of mobile app network security

Do not use to bypass pinning on apps without explicit testing authorization.

Prerequisites

• Burp Suite configured as proxy with listener on all interfaces
• Rooted Android device or jailbroken iOS device
• Frida server running on target device
• Objection installed (pip install objection)
• Target app installed and reproducing the pinning behavior

Workflow

Step 1: Identify Pinning Implementation

Android pinning methods to identify:

1. Network Security Config (res/xml/network_security_config.xml)
   <pin-set> with certificate hash pins

2. OkHttp CertificatePinner
   CertificatePinner.Builder().add("api.target.com", "sha256/...")

3. Custom TrustManager
   X509TrustManager overrides in code

4. Third-party libraries
   - TrustKit
   - Certificate Transparency checks

iOS pinning methods:

1. NSURLSession delegate (URLSession:didReceiveChallenge:)
2. ATS (App Transport Security) with custom trust evaluation
3. TrustKit framework
4. Alamofire ServerTrustPolicy
5. Custom SecTrust evaluation

Step 2: Bypass with Objection (Quickest Approach)

# Android
objection --gadget com.target.app explore
android sslpinning disable

# iOS
objection --gadget com.target.app explore
ios sslpinning disable

Objection hooks common pinning implementations including OkHttp CertificatePinner, TrustManagerImpl, NSURLSession delegate methods, and SecTrust evaluation.

Step 3: Bypass with Custom Frida Scripts

Android - Universal SSL Pinning Bypass:

// android_ssl_bypass.js
Java.perform(function() {
    // Bypass TrustManagerImpl
    var TrustManagerImpl = Java.use("com.android.org.conscrypt.TrustManagerImpl");
    TrustManagerImpl.verifyChain.implementation = function(untrustedChain, trustAnchorChain,
        host, clientAuth, ocspData, tlsSctData) {
        console.log("[+] Bypassing TrustManagerImpl for: " + host);
        return untrustedChain;
    };

    // Bypass OkHttp3 CertificatePinner
    try {
        var CertificatePinner = Java.use("okhttp3.CertificatePinner");
        CertificatePinner.check.overload("java.lang.String", "java.util.List").implementation =
            function(hostname, peerCertificates) {
                console.log("[+] Bypassing OkHttp3 pinning for: " + hostname);
                return;
            };
    } catch(e) {}

    // Bypass custom X509TrustManager
    var X509TrustManager = Java.use("javax.net.ssl.X509TrustManager");
    var TrustManager = Java.registerClass({
        name: "com.bypass.TrustManager",
        implements: [X509TrustManager],
        methods: {
            checkClientTrusted: function(chain, authType) {},
            checkServerTrusted: function(chain, authType) {},
            getAcceptedIssuers: function() { return []; }
        }
    });

    // Bypass SSLContext
    var SSLContext = Java.use("javax.net.ssl.SSLContext");
    SSLContext.init.overload("[Ljavax.net.ssl.KeyManager;",
        "[Ljavax.net.ssl.TrustManager;", "java.security.SecureRandom").implementation =
        function(km, tm, sr) {
            console.log("[+] Replacing TrustManagers in SSLContext.init");
            this.init(km, [TrustManager.$new()], sr);
        };

    // Bypass NetworkSecurityConfig (Android 7+)
    try {
        var NetworkSecurityConfig = Java.use(
            "android.security.net.config.NetworkSecurityConfig");
        NetworkSecurityConfig.isCleartextTrafficPermitted.implementation = function() {
            return true;
        };
    } catch(e) {}

    console.log("[*] SSL pinning bypass loaded");
});

frida -U -f com.target.app -l android_ssl_bypass.js --no-pause

iOS - Universal SSL Pinning Bypass:

// ios_ssl_bypass.js
if (ObjC.available) {
    // Bypass NSURLSession delegate
    var resolver = new ApiResolver("objc");
    resolver.enumerateMatches(
        "-[* URLSession:didReceiveChallenge:completionHandler:]", {
        onMatch: function(match) {
            Interceptor.attach(match.address, {
                onEnter: function(args) {
                    var completionHandler = new ObjC.Block(args[4]);
                    var NSURLSessionAuthChallengeUseCredential = 0;
                    var trust = new ObjC.Object(args[3])
                        .protectionSpace().serverTrust();
                    var credential = ObjC.classes.NSURLCredential
                        .credentialForTrust_(trust);
                    completionHandler.invoke(NSURLSessionAuthChallengeUseCredential,
                        credential);
                }
            });
        },
        onComplete: function() {}
    });

    // Bypass SecTrustEvaluate
    var SecTrustEvaluateWithError = Module.findExportByName(
        "Security", "SecTrustEvaluateWithError");
    if (SecTrustEvaluateWithError) {
        Interceptor.replace(SecTrustEvaluateWithError, new NativeCallback(
            function(trust, error) {
                return 1;  // Always return true
            }, "bool", ["pointer", "pointer"]
        ));
    }

    console.log("[*] iOS SSL pinning bypass loaded");
}

Step 4: Handle Advanced Pinning

For apps using advanced pinning (TrustKit, custom binary checks):

# Identify the specific pinning library
frida-trace -U -n TargetApp -m "*[*Trust*]" -m "*[*Pin*]" -m "*[*SSL*]" -m "*[*Certificate*]"

# Hook the identified validation function
# Custom Frida script targeting the specific implementation

Step 5: Verify Bypass Success

After applying the bypass:

1. Configure device proxy to Burp Suite
2. Open target app and navigate through authenticated flows
3. Verify HTTPS traffic appears in Burp Suite HTTP History
4. Check for any remaining pinned connections that are not captured

Key Concepts

Tools & Systems

• Objection: Pre-built pinning bypass for common libraries (OkHttp, NSURLSession, TrustKit)
• Frida: Custom JavaScript hooks targeting specific pinning implementations
• apktool: APK decompilation for identifying pinning in Network Security Config
• SSLUnpinning (Xposed): Xposed framework module for system-wide pinning bypass on Android
• ssl-kill-switch2: iOS tweak for disabling SSL pinning system-wide on jailbroken devices

Common Pitfalls

• Certificate transparency: Some apps check CT logs in addition to pinning. May need to bypass CT verification separately.
• Multi-layer pinning: Apps may implement pinning at multiple levels (OkHttp + custom TrustManager). Bypass all layers.
• Binary-level pinning: Some apps validate certificates in native C/C++ code, which requires Interceptor.attach at native function addresses rather than Java/ObjC hooks.
• Dynamic pinning updates: Apps using TrustKit or similar may fetch updated pins from a server. Monitor for pin rotation during testing.

Other files in this skill

• LICENSE
• assets/template.md
• references/api-reference.md
• references/standards.md
• references/workflows.md
• scripts/agent.py
• scripts/process.py

assets/template.md (verbatim)

Certificate Pinning Bypass Assessment Report

Target

Pinning Implementation Analysis

Findings

1. [FINDING]

Recommendations

1. [RECOMMENDATION]

references/api-reference.md (verbatim)

API Reference — Performing Mobile App Certificate Pinning Bypass

Libraries Used

• subprocess: Execute frida, objection, apktool, adb commands
• pathlib: Read decompiled APK smali files

CLI Interface

python agent.py detect --apk app.apk
python agent.py frida --package com.example.app [--device emulator-5554]
python agent.py objection --package com.example.app
python agent.py proxy

Core Functions

detect_pinning_implementation(apk_path) — Static APK analysis

Decompiles APK with apktool. Searches smali for pinning indicators: OkHttp CertificatePinner, X509TrustManager, network_security_config, WebView SSL error handler, Conscrypt TrustManagerImpl, Certificate Transparency.

run_frida_bypass(package_name, device_id) — Dynamic Frida bypass

Injects JavaScript to bypass: TrustManagerImpl.verifyChain, OkHttp CertificatePinner.check, WebViewClient.onReceivedSslError.

run_objection_bypass(package_name) — Objection framework bypass

Runs android sslpinning disable via objection exploration mode.

check_proxy_setup() — Verify interception environment

Checks: Android proxy settings, system CA certificates, user-installed CA certs.

Pinning Strength Classification

Dependencies

pip install frida-tools objection

System: apktool, adb (Android Debug Bridge)

references/standards.md (verbatim)

Standards Reference: Certificate Pinning Bypass

OWASP Mobile Top 10 2024

OWASP MASVS v2.0

CWE Mappings

references/workflows.md (verbatim)

Workflows: Certificate Pinning Bypass

Workflow 1: Escalating Bypass Approach

[Configure Burp proxy] --> [App connection fails?] --> [Yes: Pinning active]
                                                              |
                                          [Try Objection generic bypass]
                                                              |
                                                    [Traffic visible?]
                                                    /              \
                                              [Yes: Done]    [No: Advanced]
                                                              |
                                          [Identify pinning library]
                                          [frida-trace *Trust* *Pin*]
                                                              |
                                          [Write custom Frida script]
                                          [Target specific implementation]
                                                              |
                                          [Verify traffic capture]

Decision Matrix

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