Trojan:Win32/Wantvi.F is a trojan that monitors for searches performed using Internet Explorer and sends this information to a remote server. It can also download and execute arbitrary files.
Trojan:Win32/Wantvi.F is a DLL which is installed and launched by other pieces of malware (such as Trojan:Win32/Wantvi.F.dr
It uses a mutex of 'zlgjkHw0004' to ensure that no more than one copy can run at a time.
Downloads and Executes Arbitrary Files
After it has been running for some time, Trojan:Win32/Wantvi.F checks a registry value at:
and then, depending on the outcome of the check, chooses a server from one of the following locations:
It then contacts this server to download an encoded file (which contains an executable), and a location on the hard disk to where it should be saved. The executable is then saved to the specified location and run.
If this process is successful, the aforementioned registry value will be updated to reflect this. After some time, it may reset the value so that each server is used again.
At the time of publication, one of the files downloaded was a variant of the TrojanDownloader:Win32/Wixud family, which was saved to <%windir%>/system32/ppc01.exe. The other two files did not appear to be available.
Monitors Web Browsing
The trojan monitors URLs visited using Internet Explorer, looking for sites containing the following substrings:
If one of these sites is used, the trojan attempts to record the items that the user was searching for at the site. It sends the URL of the search to a server at werdagoniotu.com, which responds with a list of further URLs to visit.
At the time of publication, these URLs linked to alternate search pages, although these were not displayed during laboratory testing.
Executes Commands Stored in Registry Entries
The trojan may read and decode encoded values stored in the registry key:
It may then attempt to execute commands stored in these values.
Trojan:Win32/Wantvi.F may randomly choose to update a counter at dc.c9.b4.a1.top.list.ru
It also makes the following registry modifications:
In registry key: HKLM\Software\Microsoft\DirectShow:
Sets value: 2
With data: <value differs based on the current system time>
Sets value: 3
With data: 0x5a0
Analysis by David Wood