We all know that the ssh honeypot "kippo" is a great tool. But it is awful easy for an attacker to figure out that they are connected to a kippo honeypot. The latest trick I see people use is to run the "file" command, which is not impleneted in kippo. For example:

# file /sbin/init
bash: file: command not found

While on a real system, I would get

# file /sbin/init
/sbin/init: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0x7aa29ded613e503fb09fb75d94026f3256f01e7a, stripped

This is a bit a tricky one to "fix" in that it requires more then just a static response as the attacker may try different files to test. So it would require something like a full database of possible files to try. Or (risky...) an implementation that would use actual output from the system kippo is running on.

Maybe I will have a patch for kippo latre today to implement either solution.

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Johannes B. Ullrich, Ph.D.
SANS Technology Institute
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