Analysis by: Karl Dominguez
 PLATFORM:

Windows 98, ME, NT, 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

It modifies the affected system's HOSTS files. This prevents users from accessing certain websites.

  TECHNICAL DETAILS

Arrival Details

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

  • %System%\karld.exe
  • %System%\karld.exe
  • %System%\karld.exe
  • %System%\karld.exe
  • %System%\karld.exe
  • %System%\karld.exe
  • %SYSTEM%\karld.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
Type = 10

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
ErrorControl = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
ImagePath = %System%\{malware filename}.exe

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
DisplayName = 222

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
ObjectName = LocalSystem

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111\Security
Security = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111\Enum
0 = Root\LEGACY_111\0000

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111\Enum
Count = 1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111\Enum
NextInstance = 1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\111
malimalimali = waaaaaaaaaaaaaaaahhhhh

HOSTS File Modification

This Trojan adds the following strings to the Windows HOSTS file:

  • http://threatinfo.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FPALEVO%2EAN&VSect=Sn
  • http://threatinfo.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FPALEVO%2EAN&VSect=Sn
  • http://threatinfo.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FPALEVO%2EAN&VSect=Sn
  • http://threatinfo.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FPALEVO%2EAN&VSect=Sn
  • http://threatinfo.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM%5FPALEVO%2EAN&VSect=Sn

  SOLUTION

Minimum Scan Engine: 8.9

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

Restart in Safe Mode, and then delete this registry key

[ 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.

RESTORE
  • Close Registry Editor.

    • Step 3

    Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.

    Step 4

    Remove these strings added by the malware/grayware/spyware in the HOSTS file

    [ Learn More ]
      "DATA_GENERIC
    • Save the file and close the text editor.


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