Analysis by: Christopher Daniel So
ALIASES:

Trojan.Gen (Symantec), Trojan.Win32.Pirminay.coq (Kaspersky), W32/Pirminay.COQ!tr (Fortinet), TR/Pirminay.cld (AntiVir), Trojan.Pirminay (Ikarus)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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 connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 299,603 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 04 Feb 2011
Payload: Drops files, Downloads files, Modifies HOSTS file

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 and executes the following files:

  • %System%\{random file name}.exe - detected as TROJ_FAM_00001e3.TOMA

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{random registry key}

HKEY_LOCAL_MACHINE\SOFTWARE\{random registry key}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
6 = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
9 = {random values}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings
6 = {random values}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings
9 = {random values}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random characters} = "%System%\{random file name}.exe"

Dropping Routine

This Trojan drops the following files:

  • %System Root%\Documents and Settings\{user name}xplore.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Download Routine

This Trojan connects to the following malicious URLs:

  • http://{BLOCKED}ut4.cn/update/utu.dat

As of this writing, the said sites are inaccessible.

HOSTS File Modification

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

  • 127.0.0.1 thepiratebay.org
  • 127.0.0.1 www.thepiratebay.org
  • 127.0.0.1 mininova.org
  • 127.0.0.1 www.mininova.org
  • 127.0.0.1 forum.mininova.org
  • 127.0.0.1 blog.mininova.org
  • 127.0.0.1 suprbay.org
  • 127.0.0.1 www.suprbay.org

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.812.06
VSAPI PATTERN Date: 04 Feb 2011
VSAPI PATTERN Date: 2/4/2011 12:00:00 AM

NOTES:

Trend customers:

    Keep your pattern and scan engine files updated. Trend Micro antivirus software can clean or remove most types of computer threats. Malware, though, such as Trojans, scripts, overwriting viruses and joke programs which are identified as uncleanable, should simply be deleted.

All Internet users:

  • Use HouseCall - the Trend Micro online threat scanner to check for malware that may already be on your PC.
  • Catch malware/grayware before they affect your PC or network. Secure your Web world with Trend Micro products that offer the best anti-threat and content security solutions for home users, corporate users, and ISPs. Go here for more information on Trend Micro products that fit your needs.


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