Detecting the Pony Trojan with RegEx using CapLoader

This short video demonstrates how you can search through PCAP files with regular expressions (regex) using
CapLoader and how this can be leveraged in order to
improve IDS signatures.

The EmergingThreats snort/suricata rule mentioned in the video is
SID 2014411
“ET TROJAN Fareit/Pony Downloader Checkin 2”.

The header accept-encoding header with quality factor 0 used by the Pony malware is:
Accept-Encoding: identity, *;q=0

And here is the regular expression used to search for that exact header:
\r\nAccept-Encoding: identity, \*;q=0\r\n

After recording the video I noticed that the leaked source code for Pony 2.0 actually contains this accept-encoding header as a
hard-coded string. Have a look in the
redirect.php file, where they set
curl’s CURLOPT_HTTPHEADER to this specific string.

Pony using curl to set: Accept-Encoding: identity, *;q=0

Wanna learn more about the intended use of quality factors in HTTP accept headers?
Then have a look at section 14.1 of RFC 2616section 5.3.4 of RFC 7231, which defines how to use qvalues (i.e. quality factors) in the Accept-Encoding header.

Finally, I’d like to thank Brad Duncan for running the
malware-traffic-analysis.net website,
your PCAP files often come in handy!

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*** This is a Security Bloggers Network syndicated blog from NETRESEC Network Security Blog authored by Erik Hjelmvik. Read the original post at: http://www.netresec.com/?page=Blog&month=2018-07&post=Detecting-the-Pony-Trojan-with-RegEx-using-CapLoader