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Penetration testers and reverse engineers have discovered a simple method to bypass SSL pinning on Android Virtual Devices. The technique requires only an AVD image with Google Play Services and a few scripts, eliminating the need for complex hooking frameworks. The discovery highlights a fundamental shift in mobile security testing: traditional mitigation tactics are failing. Threat actors can now deploy mass-scale MitM attacks on custom Android builds with minimal investment.
Learning Objectives:
- Understand SSL pinning and its role in preventing man-in-the-middle attacks on Android
- Learn to configure a rooted AVD with Magisk using the rootAVD automation script
- Master the technique of injecting custom CA certificates into the system trust store
- Apply practical commands to intercept HTTPS traffic from any Android app without Frida
You Should Know:
- Setup a Rooted AVD with Magisk and Google Play Store
The rootAVD script simplifies rooting Android Virtual Devices by patching the ramdisk with Magisk. The target environment is an AVD that includes Google Play Store—many hardened apps only function on official Google-certified images. Root is non‑negotiable: Android 7.0+ ignores user‑installed CA certificates for most apps. Rooting converts a user certificate into a system‑level one.
Step-by-step guide:
- Install Android Studio and ensure the SDK Platform‑Tools are in your PATH.
2. On Linux, add the following to `~/.bashrc`:
export ANDROID_HOME="$HOME/Android/Sdk" export PATH="$PATH:$ANDROID_HOME/platform-tools"
On Windows, add `C:\Users\%USERNAME%\AppData\Local\Android\Sdk\platform-tools` to the system PATH.
3. Clone the rootAVD repository:
git clone https://gitlab.com/newbit/rootAVD.git cd rootAVD
4. Create a new AVD in Android Studio with a Google Play Store image (e.g., “Medium Phone” running API 33 with Google APIs).
5. Boot the AVD.
- Navigate to the rootAVD directory and list available AVDs:
Windows: .\rootAVD.bat ListAllAVDs Linux/macOS: ./rootAVD.sh ListAllAVDs
- Root the target AVD using the path to its ramdisk.img:
Windows: .\rootAVD.bat system-images\android-33\google_apis_playstore\x86_64\ramdisk.img Linux/macOS: ./rootAVD.sh system-images/android-33/google_apis_playstore/x86_64/ramdisk.img
The script automatically shuts down the AVD upon completion.
- Cold‑boot the AVD, open the Magisk app, and follow its prompts to finalize root access.
9. Verify root with:
adb shell emu64x:/ $ su emu64x:/ whoami root
A prompt on the AVD will request shell root access confirmation.
This method works for API levels 24 through 35. The process effectively transforms a standard AVD into a fully rooted testing environment with Magisk support. Root remains persistent across reboots, making the environment ideal for repeated testing sessions.
- Convert and Push CA Certificates for System-wide Trust
Once root access is established, the next step involves converting the proxy CA certificate into the correct format and pushing it to the device. Android’s certificate store requires certificates in DER format with a specific filename based on the subject hash.
Step-by-step guide:
- Export the CA certificate from your proxy tool:
– Burp Suite: Navigate to Proxy → Options → Import/Export CA Certificate, select “Certificate in DER format”, and save as cacert.der.
– Caido: Convert the existing PEM certificate using OpenSSL:
openssl x509 -in ca.crt -outform DER -out caido.der
2. Generate the Android subject hash:
openssl x509 -inform DER -subject_hash_old -in cacert.der | head -1
This outputs an eight-character hexadecimal hash (e.g., `9a5ba575`).
3. Rename the certificate file:
mv cacert.der 9a5ba575.0
4. Push the certificate to the AVD:
adb push 9a5ba575.0 /storage/self/primary/
The file now resides in the shared storage area accessible to the root shell.
The hash generation and renaming are critical for Android’s certificate store to recognise the file. Missing or incorrect steps result in the certificate being ignored by the system.
- Inject the CA Certificate into the System Trust Store
Android restricts modifications to the system partition, but a root shell can mount a temporary filesystem (tmpfs) over the certificates directory. This technique overrides the existing certificates without permanently modifying the system image.
Step-by-step guide:
- Create a temporary directory to back up existing certificates:
mkdir -p -m 700 /data/local/tmp/tmp-ca-copy cp /apex/com.android.conscrypt/cacerts/ /data/local/tmp/tmp-ca-copy/
- Mount a new tmpfs over the system certificates location:
mount -t tmpfs tmpfs /system/etc/security/cacerts
3. Restore the original certificates from the backup:
mv /data/local/tmp/tmp-ca-copy/ /system/etc/security/cacerts/
4. Copy the custom certificate into the now-writable directory:
cp /storage/self/primary/9a5ba575.0 /system/etc/security/cacerts/
5. Set correct permissions and SELinux contexts:
chown root:root /system/etc/security/cacerts/ chmod 644 /system/etc/security/cacerts/ chcon u:object_r:system_file:s0 /system/etc/security/cacerts/
6. Inject the mount into the Zygote process so newly launched apps see the certificates:
ZYGOTE_PID=$(pidof zygote || true) ZYGOTE64_PID=$(pidof zygote64 || true) for Z_PID in "$ZYGOTE_PID" "$ZYGOTE64_PID"; do if [ -n "$Z_PID" ]; then nsenter --mount=/proc/$Z_PID/ns/mnt -- \ /bin/mount --bind /system/etc/security/cacerts /apex/com.android.conscrypt/cacerts fi done
7. For already running apps, inject the mount into each app’s namespace:
APP_PIDS=$(echo "$ZYGOTE_PID $ZYGOTE64_PID" | xargs -n1 ps -o 'PID' -P | grep -v PID) for PID in $APP_PIDS; do nsenter --mount=/proc/$PID/ns/mnt -- \ /bin/mount --bind /system/etc/security/cacerts /apex/com.android.conscrypt/cacerts & done wait echo "System certificate injected"
The entire script can be saved as `script.sh` and executed as root.
This injection method persists only until the next reboot. For persistent installations, consider using Magisk modules like MagiskTrustUserCerts, which automatically add user certificates to the system store across reboots. Tools like `burpdrop` can also automate the entire certificate deployment process.
4. Configure Proxy and Intercept Traffic
With the CA certificate installed as a system authority, the AVD is ready for HTTPS interception. The `proxyadb` function simplifies proxy configuration and removal.
Step-by-step guide:
1. Define the `proxyadb` function in your shell:
proxyadb() {
if [[ "$1" == "--connect" ]]; then
if [[ -n "$2" && -n "$3" ]]; then
adb shell settings put global http_proxy "$2:$3"
echo "Proxy set to $2:$3"
else
echo "Please provide an IP address and a port."
fi
elif [[ "$1" == "--disconnect" ]]; then
adb shell settings put global http_proxy :0
echo "Proxy disconnected"
elif [[ "$1" == "--status" ]]; then
adb shell settings get global http_proxy
else
echo "Usage: proxyadb --connect <IP> <PORT> | --disconnect | --status"
fi
}
For bash completion, add:
_proxyadb_completions() {
local -a completions
completions=('--connect' '--disconnect' '--status')
_describe 'proxyadb options' completions
}
compdef _proxyadb_completions proxyadb
2. Connect the proxy:
proxyadb --connect 192.168.1.14 8082
Replace `192.168.1.14` with your proxy server’s IP and `8082` with the listening port.
3. Launch the target app. All HTTPS traffic should now appear in your proxy tool.
4. After testing, disconnect the proxy:
proxyadb --disconnect
The `proxyadb` function modifies Android’s global proxy settings. For apps that ignore these settings or implement custom proxy detection, additional techniques such as iptables redirection may be necessary.
- Detect and Evade SSL Pinning in Hardened Apps
While the CA certificate injection method works for many apps, some implementations employ advanced SSL pinning techniques that resist simple system certificate injection.
Detection steps:
- Monitor the proxy logs for connection resets or SSL handshake failures.
- Use `logcat` to identify pinning-related exceptions:
adb logcat | grep -i "certificate|pinning|ssl"
- Decompile the app using `jadx` or `apktool` and search for pinning implementations in the `NetworkSecurityConfig` XML or hardcoded certificate hashes in the code.
Evasion methods when simple injection fails:
- Frida scripting: Use `frida-multiple-unpinning` or Objection’s `android sslpinning disable` command for dynamic hooking.
- Xposed modules: Install `JustTrustMePro` or `TrustMeAlready` via LSPosed to bypass pinning system-wide.
- Certificate hash replacement: Patch the APK directly by replacing hardcoded certificate hashes with those of the proxy CA. Tools like `apktool` and `keytool` facilitate this process.
- Magisk modules: `MagiskTrustUserCerts` adds user certificates to the system store automatically, bypassing Android’s user certificate restrictions.
- Custom ROMs: Some custom Android builds include patches that disable system pinning checks entirely.
The choice of method depends on the app’s obfuscation level and anti-tampering mechanisms. Many modern apps combine pinning with integrity checks and environment detection, requiring a layered approach to bypass.
What Undercode Say:
- No single security control is sufficient. As the article notes, SSL pinning can no longer be considered a serious obstacle on its own. Attackers with moderate resources can bypass it using publicly available tools and scripts.
- The barrier to entry continues to fall. The technique described here requires only an emulator and a proxy, not specialised hardware or deep reverse‑engineering skills. This democratisation of attack capabilities means defenders must assume that any client‑side control can be compromised.
- Defense must shift to a multi‑layered model. Pinning should be combined with integrity checks, code obfuscation, server‑side validation, and anomaly detection. Relying on a single technique is a recipe for failure in the current threat landscape.
The post content demonstrates that intercepting traffic from mobile apps has become nearly as easy as intercepting traffic from web applications. The combination of rootable emulators and automated certificate injection scripts lowers the technical barrier significantly. Mobile threat landscapes are expanding rapidly, and the rise of AI development tools only accelerates this trend.
Prediction:
Within 12–18 months, automated frameworks will integrate AVD-based SSL bypass techniques into standard mobile security testing pipelines, reducing per-app assessment time from hours to minutes. This evolution will force a fundamental rethinking of mobile app security: developers will shift away from client-side protections and toward server-side behavioral detection and real-time anomaly scoring. The same automation that enables faster testing will also empower malicious actors to scale attacks, leading to a surge in credential harvesting and data exfiltration from mobile platforms. As a result, regulatory bodies may introduce stricter requirements for mobile app security, mandating runtime application self-protection (RASP) and continuous monitoring alongside traditional pinning mechanisms. The arms race between offensive and defensive mobile security has entered a new phase where speed and automation, not sophistication, determine outcomes.
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