Dumps TLS keys from jailbroken iOS 10.x device - requires Frida, doesn't support session resumption

iostlskeydump.py

#!/usr/bin/python

#/usr/local/bin/python

import frida
import sys

def on_message(message, data):
    
    try:
        if message:
            f = open("tlskeys.log", 'a')
            print("{0}".format(message["payload" ]))
            f.write(message["payload"] + "\n" )

    except Exception as e:
        print(message)
        print(e)


# tls_handshake_internal_prf signature from 
# https://opensource.apple.com/source/coreTLS/coreTLS-83.20.8/lib/tls1Callouts.c.auto.html
#
#   tls_handshake_t ctx,
#    const void *vsecret,
#    size_t secretLen,
#    const void *label,          // optional, NULL implies that seed contains
#                                //   the label
#    size_t labelLen,
#    const void *seed,
#    size_t seedLen,
#    void *vout,                 // mallocd by caller, length >= outLen
#    size_t outLen

hook = """


    var hexChar = ["0", "1", "2", "3", "4", "5", "6", "7","8", "9", "A", "B", "C", "D", "E", "F"];

    function byteToHex(byte) {
        return hexChar[(byte >> 4) & 0x0f] + hexChar[byte & 0x0f];
    }

    var tls_handshake_internal_prf = Module.findExportByName("libsystem_coretls.dylib", "tls_handshake_internal_prf");

    Interceptor.attach(tls_handshake_internal_prf, {onEnter: function (args) {

        var secretLength = parseInt(args[2], 16);
        var seedLength = parseInt(args[6], 16);

        if(secretLength == 48 && (seedLength == 64 || seedLength == 77)) {
        
            var secretAddr = new NativePointer(args[1])
            var secretBytes = new Uint8Array(Memory.readByteArray(secretAddr, secretLength));
            
            var secret = "";
            for(var i = 0; i < secretLength; i++) {
                secret += byteToHex(secretBytes[i]);
            }

            var seedLength = parseInt(args[6], 16);
            var seedAddr = new NativePointer(args[5]);
            var seedBytes = new Uint8Array(Memory.readByteArray(seedAddr, seedLength)); 

            var clientRandom = "";
            var serverRandom = "";
    
            if(seedLength == 64) {
                
                for(i = 0; i < 32; i++) {
                    clientRandom += byteToHex(seedBytes[i]);
                }

                for( ; i < 64; i++) {
                    serverRandom += byteToHex(seedBytes[i]);
                }
            }
            else if(seedLength == 77) { // key expansion

                var offset = 13;

                for(i = offset; i < 32 + offset; i++) {
                    serverRandom += byteToHex(seedBytes[i]);
                }

                for( ; i < 64 + offset; i++) {
                    clientRandom += byteToHex(seedBytes[i]);
                }
            }

            if(clientRandom !== "") {
                send("CLIENT_RANDOM "+ clientRandom + " " + secret);
            }
        }
    }

    });

"""

if __name__ == '__main__':
    
    try:
        print("[*] Attaching ..." )
        print("[*] Hooking... \n " )
        
        if sys.argv[1] == "-n":
            session = frida.get_usb_device().spawn(["re.frida.Gadget" ])
        else:
            session = frida.get_usb_device().spawn([sys.argv[1]])
            
        session1 = frida.get_usb_device().attach(session)
        frida.get_usb_device().resume(session)

        script = session1.create_script(hook)
        script.on('message' , on_message)
        script.load()
        sys.stdin.read()
        
    except KeyboardInterrupt:
        sys.exit(0)
        
    except IndexError:
        print("""
            Error: No process specified. Usage: dumper.py [BundleIdentifier]
            E.g. dumper.py com.apple.mobilesafari
            If device is jailbroken please use -n option
            """)