applesign

node-applesign

NodeJS module and commandline utility for re-signing iOS applications (IPA files).

Author

Sergi Alvarez aka pancake @ nowsecure.com

Program Dependencies

• zip - re-create IPA
• unzip - decompress IPA
• codesign - sign and verify binary with new entitlements and identity
• security - get entitlements from mobileprovision

Usage

$ bin/applesign.js
Usage:

  applesign.js [--options ...] [input-ipafile]
  -7, --use-7zip                Use 7zip instead of unzip
      --use-openssl             Use OpenSSL cms instead of Apple's security tool
  -b, --bundleid [BUNDLEID]     Change the bundleid when repackaging
  -c, --clone-entitlements      Clone the entitlements from the provisioning to the bin
  -e, --entitlements [ENTITL]   Specify entitlements file (EXPERIMENTAL)
  -E, --entry-entitlement       Use generic entitlement (EXPERIMENTAL)
  -f, --force-family            Force UIDeviceFamily in Info.plist to be iPhone
  -i, --identity [1C4D1A..]     Specify hash-id of the identity to use
  -I, --insert [frida.dylib]    Insert a dynamic library to the main executable
  -k, --keychain [KEYCHAIN]     Specify alternative keychain file
  -l, --lipo [arm64|armv7]      Lipo -thin all bins inside the IPA for the given architecture
  -L, --identities              List local codesign identities
  -m, --mobileprovision [FILE]  Specify the mobileprovision file to use
  -M, --massage-entitlements    Massage entitlements to remove privileged ones
  -o, --output [APP.IPA]        Path to the output IPA filename
  -p, --parallel                Run layered signing dependencies in parallel
  -r, --replace                 Replace the input IPA file with the resigned one
  -s, --single                  Sign a single file instead of an IPA
  -S, --self-sign-provision     Self-sign mobile provisioning (EXPERIMENTAL)
  -u, --unfair                  Resign encrypted applications
  -v, --verify-twice            Verify after signing every file and at the end
  -V, --dont-verify             Avoid verification step of codesigning
  -w, --without-watchapp        Remove the WatchApp from the IPA before resigning
      --version                 Show applesign version
  [input-ipafile]               Path to the IPA file to resign

Example:

  applesign.js -L # enumerate codesign identities, grab one and use it with -i
  applesign.js -i AD71EB42BC289A2B9FD3C2D5C9F02D923495A23C test-app.ipa

List local codesign identities:

$ bin/applesign -I

Resign an IPA with a specific identity:

$ bin/applesign -i 1C4D1A442A623A91E6656F74D170A711CB1D257A foo.ipa

Change bundleid:

$ bin/applesign -b org.nowsecure.testapp path/to/ipa

Signing methods

There are different ways to sign an IPA file with applesign for experimental reasons.

You may want to check the following options:

-c, --clone-entitlements

put the entitlements embedded inside the signed mobileprovisioning file provided by the user as the default ones to sign all the binaries

-S, --self-sign-provision

creates a custom mobileprovisioning (unsigned for now). installd complains

-E, --entry-entitlement

use the default entitlements plist. useful when troubleshooting

The default signing method does as follow:

• Grab entitlements from binary
• Remove problematic entitlements
• Grab entitlements from the provisioning
• Adjust application-id and team-id of the binary with the provisioning ones
• Copy the original mobileprovisioning inside the IPA
• Creates ${AppName}.entitlements and signs all the mach0s

After some testing we will probably go for having -c or -E as default.

In addition, for performance reasons, applesign supports -p for parallel signing. The order of signing the binaries inside an IPA matters, so applesign creates a dependency list of all the bins and signs them in order. The parallel signing aims to run in parallel as much tasks as possible without breaking the dependency list.

Mangling

It is possible with --force-family to remove the UISupportedDevices from the Info.plist and replace the entitlement information found in the mobileprovisioning and then carefully massage the rest of entitlements to drop the privileged ones (--massage-entitlements).

Other interesting manipulations that can be done in the IPA are:

-I, --insert [frida.dylib]

Allows to insert a dynamic library in the main executable. This is how Frida can be injected to introspect iOS applications without jailbreak.

-l, --lipo [arm64|armv7]

Thinifies an IPA by removing all fatmach0s to only contain binaries for one specified architecture. Also this is helpful to identify non-arm binaries embedded inside IPA that can be leaked from development or pre-production environments.

In order to thinify the final IPA even more, applesign allows to drop the watchapp extensions which would not be necessary for non Apple Watch users.

Performance

Sometimes the time required to run the codesigning step matters, so applesign allows to skip some steps and speedup the process.

See --dont-verify and --parallel commandline flags.

Enabling those options can result on a 35% speedup on ~60MB IPAs.

API usage

Here's a simple program that resigns an IPA:

const Applesign = require('applesign');

const as = new Applesign({
  identity: '81A24300FE2A8EAA99A9601FDA3EA811CD80526A',
  mobileprovision: '/path/to/dev.mobileprovision',
  withoutWatchapp: true
});

const s = as.signIPA('/path/to/app.ipa', onEnd)
  .on('warning', (msg) => {
    console.log('WARNING', msg);
  })
  .on('message', (msg) => {
    console.log('msg', msg);
  });

function onEnd(err, data) {
  if (err) {
    console.error(err);
    s.cleanup();
    process.exit(1);
  } else {
    console.log('ios-deploy -b', as.config.outfile);
    process.exit(0);
  }
}

To list the developer identities available in the system:

as.getIdentities((err, ids) => {
  if (err) {
    console.error(err, ids);
  } else {
    ids.forEach((id) => {
      console.log(id.hash, id.name);
    });
  }
});

Bear in mind that the Applesign object can tuned to use different configuration options:

const options = {
  file: '/path/to/app.ipa',
  outfile: '/path/to/app-resigned.ipa',
  entitlement: '/path/to/entitlement',
  bundleid: 'app.company.bundleid',
  identity: 'hash id of the developer',
  mobileprovision: '/path/to/mobileprovision file',
  ignoreVerificationErrors: true,
  withoutWatchapp: true
};

Further reading

See the Wiki: https://github.com/nowsecure/node-applesign/wiki

• https://github.com/maciekish/iReSign
• https://github.com/saucelabs/isign
• https://github.com/phonegap/ios-deploy

Pre iOS9 devices will require a developer account:

• http://dev.mlsdigital.net/posts/how-to-resign-an-ios-app-from-external-developers/