frida-17

Imported from yfe404/frida-17-skill (SKILL.md) via skills.sh. Install upstream with npx skills add yfe404/frida-17-skill. Copyright stays with the author.

Frida 17 Scripting Guide

This skill helps write and fix Frida scripts compatible with Frida 17.0.0 (released May 2025).

Breaking Changes in Frida 17

1. Static Module Methods - REMOVED

// OLD - No longer works in Frida 17
Module.findBaseAddress('libriver.so')
Module.getBaseAddress('libriver.so')
Module.findExportByName(null, 'open')
Module.findExportByName('libc.so', 'open')
Module.getExportByName(null, 'open')
Module.ensureInitialized('libc.so')
Module.enumerateExports('libc.so')
Module.enumerateSymbols('libc.so')

// NEW - Use Process and instance methods instead
var lib = Process.findModuleByName('libriver.so');  // returns Module or null
var lib = Process.getModuleByName('libriver.so');   // throws if not found
lib.base                                             // module base address
lib.findExportByName('open')                        // returns address or null
lib.getExportByName('open')                         // throws if not found
lib.enumerateExports()                              // returns array
lib.enumerateSymbols()                              // returns array

2. Static Memory Methods - REMOVED

// OLD - No longer works
Memory.readU32(ptr)
Memory.writeU32(ptr, value)

// NEW - Use NativePointer instance methods
ptr.readU32()
ptr.writeU32(value)

3. Legacy Enumeration APIs - REMOVED

// OLD - Callback style removed
Process.enumerateModules({ onMatch: fn, onComplete: fn })
Process.enumerateModulesSync()

// NEW - Returns array directly
Process.enumerateModules()

4. Reserved Function Names - DO NOT OVERRIDE

The following are built-in Frida functions. Defining custom functions with these names causes: TypeError: cannot define variable 'hexdump'

Reserved names:

• hexdump - Use dumpHex instead for custom hex dump functions
• ptr - pointer constructor shorthand
• NULL - null pointer constant

// BAD - conflicts with built-in
function hexdump(ptr, len) { ... }

// GOOD - use different name
function dumpHex(ptr, len) { ... }

NativePointer Methods (Valid in Frida 17)

Conversion:

• toInt32() - cast to signed 32-bit integer
• toNumber() - convert to JavaScript number
• toString([radix]) - convert to string

NOT available:

• toUInt32() - DOES NOT EXIST, use toInt32() for sizes < 2^31

Memory reading:

• readU8(), readS8(), readU16(), readS16()
• readU32(), readS32(), readU64(), readS64()
• readByteArray(length) - returns ArrayBuffer
• readPointer(), readCString(), readUtf8String()

Memory writing:

• writeU8(value), writeS8(value), etc.
• writeByteArray(bytes) - bytes must be ArrayBuffer or JS array
• writePointer(ptr), writeUtf8String(str)

Pointer arithmetic:

• add(rhs), sub(rhs), and(rhs), or(rhs), xor(rhs)
• shr(n), shl(n), not()
• isNull(), equals(rhs), compare(rhs)

Java Bridge API (Unchanged in Frida 17)

Java.perform(function() {
    var MyClass = Java.use('com.example.MyClass');

    // Hook with overload
    MyClass.myMethod.overload('int', 'java.lang.String').implementation = function(a, b) {
        console.log('Called with: ' + a + ', ' + b);
        // Call original
        return this.myMethod.overload('int', 'java.lang.String').call(this, a, b);
    };

    // Hook all overloads
    MyClass.myMethod.overloads.forEach(function(overload) {
        overload.implementation = function() {
            return overload.apply(this, arguments);
        };
    });
});

Java byte[] handling: Java byte arrays cannot be passed directly to Memory.alloc().writeByteArray(). Convert manually:

// BAD - throws "expected a buffer-like object"
var hex = dumpHex(Memory.alloc(javaByteArray.length).writeByteArray(javaByteArray), len);

// GOOD - iterate and convert
var hex = "";
for (var i = 0; i < javaByteArray.length; i++) {
    hex += ("0" + (javaByteArray[i] & 0xff).toString(16)).slice(-2);
}

Common Patterns for Frida 17

Waiting for a library to load

function waitForLibrary(libName, callback) {
    var lib = Process.findModuleByName(libName);
    if (lib) {
        callback(lib.base);
        return;
    }
    var pollInterval = setInterval(function() {
        var lib = Process.findModuleByName(libName);
        if (lib) {
            clearInterval(pollInterval);
            callback(lib.base);
        }
    }, 500);
}

Hooking libc functions

var libc = Process.findModuleByName('libc.so');
var open = libc ? libc.findExportByName('open') : null;
if (open) {
    Interceptor.attach(open, {
        onEnter: function(args) {
            console.log('open(' + args[0].readCString() + ')');
        }
    });
}

Custom hex dump function

function dumpHex(ptr, len) {
    if (!ptr || ptr.isNull()) return 'null';
    try {
        var bytes = ptr.readByteArray(len);
        if (!bytes) return 'null';
        var arr = new Uint8Array(bytes);
        var hex = '';
        for (var i = 0; i < arr.length; i++) {
            hex += ('0' + arr[i].toString(16)).slice(-2);
        }
        return hex;
    } catch (e) {
        return 'error: ' + e;
    }
}

Checklist for Frida 17 Compatibility

When reviewing a Frida script, check for:

1. Module.findBaseAddress() -> Process.findModuleByName().base
2. Module.getBaseAddress() -> Process.getModuleByName().base
3. Module.findExportByName(null, name) -> Process.findModuleByName('libc.so').findExportByName(name)
4. Module.findExportByName(lib, name) -> Process.findModuleByName(lib).findExportByName(name)
5. Module.enumerateExports(lib) -> Process.getModuleByName(lib).enumerateExports()
6. Module.enumerateSymbols(lib) -> Process.getModuleByName(lib).enumerateSymbols()
7. Memory.readU32(ptr) -> ptr.readU32()
8. toUInt32() -> toInt32() (toUInt32 never existed)
9. function hexdump() -> function dumpHex() (name conflict)
10. Java byte[] with writeByteArray() -> manual hex conversion

References

• Frida 17.0.0 Release Notes
• Frida JavaScript API
• Frida Android Examples