We have been investigating and analyzing a variety of malicious components delivered from some recent downloaders. Some of the filenames stand out as unusual. In particular, “podmena”,
which translates from russian to english as “Substitution or replacement made in a covert way (“pod” – “sub” or “under”, sort of under cover; “mena” – the root of word exchange); thus, it often stands for “spoof”, “fake”, etc. “Spoof”. It is fitting.
The two “podmena” files dropped by the phony codec/viewer installs seem to be gathering much interest and gaining prevalence. They’ll be discussed here and the post itself will be updated with new information as it is uncovered.
First off, the files are dropped as one of the may payloads during the phony codec downloader attacks described in previous posts here, here and here. The components seem to be a part of a click fraud scheme and a way to generate potentially artificial traffic volume to several search engines, including bee-find.com, missngpage.com, 102.123bounce.com, and www.search.pro.
Podmena.dll gets registered as a ServiceDll to be run via svchost.exe -k podmena.dll.
Podmena.sys is installed as a kernel driver to run at startup and attaches to DeviceTcp, intercepting all tcp related IRPs.
The Dll upon startup sends a DeviceIoControl() request to the driver opened on \.podmena. The initial IO control code tells the driver to monitor outbound tcp port 80, and redirect all packets to 127.0.0.1:8085. Then, the dll sends a second io control code to the driver, which activates the forwarding.
The Dll will create a bound listening port on 8085 which now acts as an HTTP proxy for all outbout port 80 traffic. Upon packet reception (after it is redirected by the driver), the Dll will scan the requested url for search keywords based on the domain name of the request. (ie: search.yahoo, google, youtube, yahooapis, metacafe, sugg.search, aolcdn, etc)
When a keyword is found, it will submit the text to its parent controller (the binaries that we have seen hard code “zz-dn.com”, which is unavailable, and then falls back to 126.96.36.199, an ip hosted in London). Depending on some timing randomization, the Dll will then load up and send the web browser to urls based on the response it receives back from this parent controller.
In our lab, subsequent requests were sent to a variety of sites, with all of these sites hosting a variety of ads, even without visiting a search engine. The svchost process loaded up with podmena.dll can visit hundreds of sites approximately every ten minutes, depending on the instruction response it receives.
Oddly, we have not seen higher target moneymakers like banking userid’s and passwords stolen by these components.