Flutter applications bundle their own BoringSSL implementation and do not honor Android's network security config, so repackaging to trust user CAs requires patching the internal certificate verification function ssl_crypto_x509_session_verify_cert_chain in libflutter.so. Since libflutter.so is shipped stripped, traditional byte signature scanning is unreliable and breaks silently with compiler changes. The author presents a method to locate this function on ARM64 by cross-referencing the unique strings 'ssl_client' and 'ssl_server' and verifying a specific prologue pattern involving a store through register x2. This approach yields at most two candidates per binary, facilitating reliable patching. The method was tested on 13 apps across Flutter engine versions 2.19.2 to 3.11.1, confirming consistent function identification. The report also notes an issue with patching tools that only open base.apk and miss split_config.arm64_v8a.apk where libflutter.so often resides. No exploits in the wild or vendor advisories are referenced.

The impact relates to the difficulty of reliably patching Flutter apps to modify TLS certificate verification due to stripped binaries and compiler variability. Without this method, attempts to repatch the certificate verifier may fail silently, causing apps to fail TLS decryption and appear to function normally, potentially hindering security research or custom trust configurations. There is no indication of a direct vulnerability or exploit affecting end users.

No official patches or vendor advisories are available. This is a technical technique for locating and patching a function in stripped Flutter binaries. Users requiring modification of Flutter's TLS verification must apply this method or similar approaches to reliably identify the target function. No generic mitigations or urgent actions are indicated.