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WORM_SCAR.TI

October 09, 2012
 ALIASES:

Trojan.Gen (Symantec); Trojan:Win32/Alureon.CT (Microsoft); Trojan-Dropper.Win32.TDSS.efj (Kaspersky); Generic Dropper.uc (Mcafee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • 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 copies of itself in all removable drives.

  TECHNICAL DETAILS

File Size:

119,808 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 May 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:

  • %User Temp%\{malware filename}.exe

(Note: %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.)

Autostart Technique

This worm modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe, %User Temp%\{malware file name}.exe"

(Note: The default value data of the said registry entry is "%System%\userinit.exe,".)

Other System Modifications

This worm adds the following registry entries:

HKEY_USERS\.DEFAULT\Software\
Microsoft\Internet Explorer\international
acceptlanguage = "en-us"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Internet Explorer\Main\
featurecontrol\FEATURE_BROWSER_EMULATION
svchost.exe = "dword:000022b8"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings
maxhttpredirects = "dword:000022b8"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings
enablehttp1_1 = "1"

It modifies the following registry entries:

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

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 2

(Note: The default value data of the said registry entry is 0.)

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\Zones\3
CurrentLevel = 0

(Note: The default value data of the said registry entry is 11000.)

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\Zones\3
1601 = 0

(Note: The default value data of the said registry entry is 1.)

Propagation

This worm drops copies of itself in all removable drives.