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WORM_SOCKS.EC

October 11, 2013
 Modified by: Sabrina Lei Sioting
 ALIASES:

Worm:Win32/Autorun.gen!BS (Microsoft), W32/Socks.A.gen!Eldorado (Authentium), Worm.Socks-11 (ClamAV), W32/Socks.A.gen!Eldorado (Fprot), Worm.Win32.Socks (Ikarus),

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Propagates via removable drives

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.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

913,405 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Jul 2009

Payload:

Connects to URLs/IPs, Compromises system security, Drops files

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:

  • %AppDataLocal%\cftmon.exe
  • %System%\drivers\spools.exe

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • z3sd

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
ntuser = "%System%\drivers\spools.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
autoload = "%AppDataLocal%\cftmon.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
ntuser = "%System%\drivers\spools.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
autoload = "%AppDataLocal%\cftmon.exe"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
UserInit = "%System%\userinit.exe,"

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

Other System Modifications

This worm modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
UIHost = "logonui.exe"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Schedule
ImagePath = "%System%\drivers\spools.exe"

(Note: The default value data of the said registry entry is %SystemRoot%\System32\svchost.exe -k netsvcs.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • autorun.exe

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:

[autorun]
ShellExecute=autorun.exe

Backdoor Routine

This worm executes the following commands from a remote malicious user:

  • Gathers running processes
  • Kills process
  • Download other files

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}.com/
  • http://{BLOCKED}.net/

Dropping Routine

This worm drops the following files:

  • %User Profile%\ftpdll.dll - detected as TROJ_SMALL.KGX
  • %System%\ftpdll.dll - detected as TROJ_SMALL.KGX

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}edomains.com/domain_profile.cfm?d=fewfwe&e=com

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

6.268.05

FIRST VSAPI PATTERN DATE:

17 Jul 2009

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Remove the malware/grayware file dropped/downloaded by WORM_SOCKS.EC

    TROJ_SMALL.KGX

Step 3

Identify and delete files detected as WORM_SOCKS.EC using either the Startup Disk or Recovery Console

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • ntuser = "%System%\drivers\spools.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • autoload = "%AppDataLocal%\cftmon.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • ntuser = "%System%\drivers\spools.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • autoload = "%AppDataLocal%\cftmon.exe"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe"
      To: Shell = Explorer.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: UserInit = "%System%\userinit.exe,"
      To: UserInit = %System%\userinit.exe,
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: UIHost = "logonui.exe"
      To: UIHost = logonui.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Schedule
    • From: ImagePath = "%System%\drivers\spools.exe"
      To: ImagePath = %SystemRoot%\System32\svchost.exe -k netsvcs

Step 6

Search and delete AUTORUN.INF files created by WORM_SOCKS.EC that contain these strings

[ Learn More ]
[autorun]
ShellExecute=autorun.exe

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_SOCKS.EC. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 8

Restore this deleted registry key/value from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects


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