I'm working on securing apps from malware attack in project. I just want to know how app is repackaged with malware. Because for reverse engg. we've apktool, dex2jar, Java decompiler. But how intruders change code in java and then repackage it. Because I think it is not possible to get jar to dex. Please help.

closed as not a real question by rook, Gilles, user10211, AJ Henderson, Iszi Apr 9 '13 at 14:21

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  • This question doesn't make sense. It's always possible to change the code. What do you mean by “not possible to get jar to dex”? – Gilles Apr 8 '13 at 0:52
  • You can patch the application by making changes in resources/SMALI code and then you can recompile it using Apktool and then you can resign it using jarsigner/apksigner. – Shiv Sahni Feb 22 '18 at 18:12

There is a wealth of information on cracking android apps or more generally patching java bytecode. Adding malware to an app is a very similar process to removing some naive client side security check.

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