Just An Application

September 5, 2014

The Mystery Of The Unsigned JAR: Part One — Enter A Small JAR, Furtively

Filed under: Security, Things That Go Bump In The Night — Tags: , , — Simon Lewis @ 6:41 am

The unsolicited contributions to my PDF collection seem to have dried up which is a bit of a disappointment. I hope it wasn’t something I said.

I have had a couple more ZIPed .exes but they are not really my kind of thing, then I got sent a JAR file.

Initially I suspected it might be a ZIPed .exe in disguise, which would have been something of an anti-climax, but it turns out to be an actual JAR with a manifest and everything.

Its not exactly the world’s biggest JAR file. Its about 50KB and contains a manifest, four class files and a dll.

More accurately it contains

  • a manifest which is definitely a manifest

  • four class files which are definitely class files since javap can parse them, and

  • a file which has the suffix .dll but which file cannot identify

After taking a quick look at the class files courtesy of ‘javap -c -private‘ there are three things that stand out

  1. there is a ‘sekrit method’

  2. there is a class loader without any classes to load unless it is a very narcissistic class loader which only loads itself

  3. there is something which purports to be a dll and in all probability isn’t

Copyright (c) 2014 By Simon Lewis. All Rights Reserved.

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