BKDR_MATSNU.A

January 31, 2013
 Analysis by: Rhena Inocencio
 ALIASES:

Trojan:Win32/Matsnu (Microsoft), Ransom-Matsnu (McAfee), Win32/Kryptik.ASVV trojan (ESET), Mal/EncPk-AGD (Sophos)

 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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

81,408 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Jan 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:

  • %User Temp%\{random file name 2}.{random extension}
  • %User Temp%\{random folder name}\{random file name 1}.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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It injects codes into the following process(es):

  • svchost.exe
  • ctfmon.exe
  • explorer.exe

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random name} = "%User Temp%\{random folder name}\{random file name 1}.exe"

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}tory.net/UTP402HEAD.php
  • http://{BLOCKED}bspace-apo.com/user-057708/forum.php
  • http://{BLOCKED}sx.com/a.php
  • http://{BLOCKED}z.com/a.php
  • http://{BLOCKED}rz.com/a.php
  • http://{BLOCKED}ppf.com/a.php
  • http://{BLOCKED}ieg.com/a.php
  • http://{BLOCKED}kiu.com/odriw0/forum.php
  • http://{BLOCKED}w.com/a.php
  • http://{BLOCKED}sje.com/a.php
  • http://{BLOCKED}sxf.com/UTP402HEAD.php
  • http://{BLOCKED}z.com/UTP402HEAD.php
  • http://{BLOCKED}xrz.com/UTP402HEAD.php
  • http://{BLOCKED}hppf.com/UTP402HEAD.php
  • http://{BLOCKED}wieg.com/UTP402HEAD.php
  • http://{BLOCKED}vw.com/UTP402HEAD.php
  • http://{BLOCKED}vsje.com/UTP402HEAD.php
  • http://{BLOCKED}oum.com/typo3.php
  • http://{BLOCKED}tory.net/UTP402HEAD.php
  • http://{BLOCKED}tory.net/forum.php
  • http://{BLOCKED}olderx.net/UTP402HEAD.php
  • http://{BLOCKED}olderxx.com/a.php
  • http://{BLOCKED}neh.com/incoming.php

It deletes the initially executed copy of itself