Abstract Dynamic library injection is a core technique used in iOS reverse engineering, security research, and third-party modification (e.g., tweaks, cheating, or debugging). This paper provides a systematic approach to injecting a custom .dylib into an existing .ipa file, covering dependency resolution, code signing bypasses, and modern anti-detection countermeasures. 1. Introduction An IPA (iOS App Store Package) is a ZIP archive containing an executable and resources. Under iOS’s code signing and integrity checks, modifying an IPA invalidates its signature. Dynamic injection bypasses this by adding a load command ( LC_LOAD_DYLIB ) to the main binary, forcing it to load an external library.
cd ../../.. zip -qr patched_$IPA Payload/ rm -rf $WORKDIR
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install_name_tool -change @rpath/libsomething.dylib @executable_path/libsomething.dylib YourTweak.dylib iOS requires all binaries (main executable + dylib) to be signed, even with an ad-hoc signature.
file MyApp # MyApp: Mach-O 64-bit executable arm64 Method A — Using insert_dylib (recommended):
( ent.plist ):
ldid -Sent.plist MyApp_patched ldid -S YourTweak.dylib , use a developer certificate:
optool install -c load -p "@executable_path/YourTweak.dylib" -t MyApp cp YourTweak.dylib . 3.5. (Optional) Modify Dependencies with install_name_tool If your dylib depends on other dylibs, adjust rpaths:
