Analysis by: Arvin Roi Macaraeg
ALIASES:

Worm:Win32/Taterf.AA(Microsoft), Trojan-GameThief.Win32.OnLineGames.tne(Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size: 103,516 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 04 Mar 2011

Arrival Details

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Worm drops the following copies of itself into the affected system:

  • %System Root%\b.com

It drops the following files:

  • %System%\amvo0.dll
  • %System%\{random filename}.sys
  • %System%\autorun.inf
  • %User Temp%\r894w8s.dll
  • %User Temp%\{random filename}.sys

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, and 8.)

Autostart Technique

This Worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
amva = %System%\amvo.exe

Other System Modifications

This Worm modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 0

Propagation

This Worm drops the following copies of itself in all physical and removable drives:

  • {Drive Letter}:\b.com

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

;4s5wiksiwk9olKd2AKrDikw4rr3k1a5aikKwwadr1koJjc3qLkSid6esSwi4rwe3ok2lomKZf3e5p
[AutoRun]
;klp4a3d93sowof5SJKO2a1olceA
open=b.com
;idokailDw17kl8ZwKSc21lwdDse34iDlaXlao9s7wsKjAJdAKlalZa2rrakS1ki244qkKFfpq4koJ3LLlkAqaLdA4s30iDrisiefS2nsss8a1ds9rqpdA5Sa51a
shell\open\Command=b.com
;Zsf148pkK3JKLAodwLDrsl03cjrL32Jljksia8we2ekfkok24wkjiDs4iD3
shell\open\Default=1
;Jra5jco24KODiwaLl1K5awk5Aaskrksi4ld4fA29Dio2LsD1fjko3eesS3kwidjrA7qCd33J4ia6ow4sK0oZa283
shell\explore\Command=b.com
;aAs4wcK9rfqDe5akoiAs52j