Win32/Taterf.DM is a worm that spread via mapped drives in order to steal login and account details for popular online games.
Installation
When executed, Win32/Taterf.DM copies itself to the system directory as a hidden file using one of the following file names:
amvo<number>.exe
kavo<number>.exe
awda<number>.exe
avpo<number>.exe
cyban.exe
xvassdf.exe
- uret463.exe
- herss.exe
- olhrwef.exe
- nodqq.exe
- ahnsbsb.exe
- i8ikdjwt.exe
- 1thes92p.exe
- kva8wr.exe
- aqoeerw.exe
- ckvo.exe
- kxvo.exe
The registry is modified to run the copy at each Windows start (for example):
Adds value: "amva"
With data: "<system folder>\amvo<number>.exe"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Adds value: "avpa"
With data: "<system folder>\avpo<number>.exe"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Note: Filenames and registry modifications differ according to variant.
The functionality to perform Win32/Taterf.DM's password-stealing payload is contained in a dll component which is also dropped to the system directory using one of the following file names:
Where <number> may be omitted entirely, or be a numeral from 0-9.
Once dropped, the dll is injected into "explorer.exe" or "iexplore.exe". These dlls may be detected as Worm:Win32/Taterf.DM.<variant letter>.dll, according to variant.
It should be noted that, in order to evade detection, the authors of Win32/Taterf.DM may pack the worm's executable. In cases such as these, the worm may be detected with the following names:
A driver with a randomly generated file name may also be dropped in the %temp% directory depending on which packer is used. This driver is detected as either VirTool:WinNT/Vanti.gen!A or VirTool:WinNT/Vanti.B. The above mentioned DLLs may also be written to the %temp% directory when these packers are used. The Vanti detections may also drop a driver which clears the SSDT (System Service Descriptor Table, a rootkit component), in order to avoid detection.
Spreads Via...
Mapped removable and network drives
The worm continually enumerates drives from C- Z, copying itself to the root of the drive, and creating an 'autorun.inf' file, which points to one of the copies that it creates. When the removable or networked drive is accessed from another computer supporting the Autorun feature, the malware is launched automatically. This 'autorun.inf' file is detected as Worm:Win32/Taterf!inf.
The name that the worm uses to copy itself to in the root of the drive differs across variants, however, it usually consists of random letters and numbers with a '.com', 'cmd' or an '.exe' extension.
For example:
q.com
d.com
d6fagcs8.cmd
gjn2pjlw.exe
h1dwg20.exe
h6o0re.cmd
Payload
Steals online game data
Once injected, the DLL is used to obtain account information for one or more of the following Massively Multiplayer Online Games and affiliated products:
Rainbow Island
Cabal Online
A Chinese Odyssey
Hao Fang Battle Net
Lineage
Gamania
MapleStory
qqgame
Legend of Mir
World Of Warcraft
As part of this process, Worm:Win32/Taterf.DM may monitor the following processes related to online games:
amo.exe
cabalmain.exe
cc.exe
client.exe
dakerden.exe
dakeron.exe
dnf.exe
ffclient.exe
ge.exe
gersang.exe
goonzu.exe
hevaonline.exe
inphasenxd.exe
knightonline.exe
main.exe
maplestory.exe
mir3game.exe
mixer.exe
nida.exe
so3d.exe
winbaram.exe
wow.exe
The captured details are sent to a remote server.
Modifies system settings
Win32/Taterf.DM modifies the following registry modifications, which specify how hidden folders and files are displayed using Windows Explorer:
HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\NoDriveTypeAutoRun
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\ShowSuperHidden
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Hidden
HKLM\Software\Microsoft\Windows\CurrentVersion\explorer\Advanced\Folder\Hidden\SHOWALL\CheckedValue
Downloads arbitrary files
The worm contacts the a specific domain in order to download files and update itself. In the wild, we have observed the malware contacting the following Web sites to download arbitrary files:
om7890.com
googlew65.com
yahooui0.com
Modifies system security settings
The worm attempts to circumvent security products by:
Attempting to prevent AVP Antivirus from displaying notifications regarding system changes by closing windows used by this product.
Attempting to terminate Ravmon.exe if it is found to be running on the affected system.
Analysis by Matt McCormack
