BKDR_SERVLOD.A

December 27, 2013
 Analysis by: Mark Joseph Manahan
 ALIASES:

Backdoor.Trojan (Symantec), RDN/Generic.dx!c2j (McAfee), BehavesLike.Win32.Malware.wsc (mx-v) (Sunbelt)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size:

208,896 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

27 Dec 2013

Arrival Details

This backdoor 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 backdoor drops the following copies of itself into the affected system and executes them:

  • %Windows%\Wmiservjuc.exe

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

Autostart Technique

This backdoor 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\WWC
ImagePath = "%Windows%\Wmiservjuc.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC
DisplayName = "Windows Web Client"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC
Type = "16"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC
Description = Windows Applications to access the Inter(R) Management and Security Application using its locally-available selected network interfaces.

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WWC\Enum

Other Details

This backdoor connects to the following possibly malicious URL:

  • r.{BLOCKED}s.ms