Analysis by: Nikko Tamana
ALIASES:

W32/Zapchast.AFFV!tr (Fortinet), Backdoor.Win32.Datcaen (Ikarus), a variant of Win32/Pucedoor.A trojan (NOD32)

 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:

  • 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: 118,784 bytes
File Type: EXE
Initial Samples Received Date: 16 May 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 file(s)/component(s):

  • %System%\usrsvpla.dll

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

Autostart Technique

This backdoor modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WmdmPmSN\Parameters ServiceDll
ServiceDll = "%SystemRoot%\System32\usrsvpla.dll"

(Note: The default value data of the said registry entry is "%System%\mspmsnsv.dll".)

Other System Modifications

This backdoor modifies the following registry entries:

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

(Note: The default value data of the said registry entry is "3" .)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://yui.{BLOCKED}rd.com/8jwpc/odw3ux
  • http://yui.{BLOCKED}rd.com/oi2c/wlc3/{Computer Name}:{hex values}-{hex values}-{hex values}-{hex values}-{hex values}-{hex values}/ij83d