nanog mailing list archives

Re: Synful Knock questions...


From: "Ricky Beam" <jfbeam () gmail com>
Date: Tue, 15 Sep 2015 15:27:47 -0400

On Tue, 15 Sep 2015 14:35:44 -0400, Michael Douglas <Michael.Douglas () ieee org> wrote:
Does anyone have a sample of a backdoored IOS image?

The IOS image isn't what gets modified. ROMMON is altered to patch IOS after decompression before passing control to it. I don't know WTF they're going on and on about "file size". There are many reasons to overwrite. The most likely reason the hack does this is because it's easier than a dynamic allocation of executable memory. Plus, modifications done by ROMMON cannot allocate IOS system memory; their hooks MUST rewrite existing code SOMEWHERE.

Again, this is a ROMMON HACK, that doctors the running IOS image IN MEMORY before starting IOS.


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