Win32/Taterf is a family of worms that spread via mapped drives in order to steal login and account details for popular online games.
Installation
When executed, Taterf copies itself to the system directory as a hidden file using one of the following file names:
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amvo<number>.exe
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kavo<number>.exe
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awda<number>.exe
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avpo<number>.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 Taterf'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.<variant letter>.dll, according to variant.
It should be noted, that in order to evade detection, the authors of this family 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.A or VirTool:WinNT/Vanti.B. The above mentioned dlls may also be written to the %temp% directory when these packers are used.
Spreads Via...
Mapped Drives
The worm continually enumerates drives from C- Z, copying itself to the root of the drive, and creating an 'autorun.inf' file. The autorun.inf is used to execute the worm whenever the drive is viewed with Windows Explorer. This 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
The captured details are sent to a remote server.
Modifies System Settings
The following registry entries are modified in order to hinder detection and removal, and facilitate spreading:
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 om7890.com domain in order to download files and update itself.
Modifies System Security Settings
The worm attempts to circumvent security products by:
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Attempting to prevent AVP Antivirus from displaying notifications regarding system changes by closing windows used by this product.
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Attempting to terminate Ravmon.exe if it is found to be running on the affected system.
Analysis by Matt McCormack
