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TSPY_PIRMINAY.B

February 04, 2013
 Analysis by: Sabrina Lei Sioting
 ALIASES:

Trojan:Win32/Vundo.gen!CD (Microsoft), Downloader (Symantec), W32/Pirminay.ANJ!tr (Fortinet),

 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:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


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

It executes then deletes itself afterward.

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

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

214,016 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Apr 2011

Payload:

Modifies HOSTS file

Arrival Details

This spyware 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 spyware drops the following component file(s):

  • %Application Data%\{random}.exe - also detected as TSPY_PIRMINAY.B
  • %System%\{random}.exe - also detected as TSPY_PIRMINAY.B

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It executes then deletes itself afterward.

It injects threads into the following normal process(es):

  • explorer.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random} = "%Application Data%\{random}.exe"

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

Other System Modifications

This spyware adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\{random}

HKEY_LOCAL_MACHINE\Software\{random}

Download Routine

This spyware connects to the following URL(s) to download its component file(s):

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

HOSTS File Modification

This spyware modifies the affected system's HOSTS files to prevent a user from accessing the following websites:

  • 127.0.0.1 localhost
  • 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

Information Theft

This spyware gathers the following data:

  • Registry Information
  • Typed urls count
  • Visited urls count
  • Uninstalled entries count
  • HKEY_LOCAL_MACHINE and HKEY_CURRENT_USER keys
  • System Information
  • Display resolution
  • Drivers count found in system32/drivers
  • Volume Information
  • Disk Free Space

Stolen Information

This spyware sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}tfriendly.com/html/license_{hex numbers}.html

Other Details

However, as of this writing, the said sites are inaccessible.

NOTES:

It checks if the user has administrative privileges.

  SOLUTION

Minimum Scan Engine:

9.300

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

[ Learn More ]

Step 3

Delete this registry value

[ 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.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random} = "%Application Data%\{random}.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • {random} = "%System%\{random}.exe"

Step 4

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.

  • In HKEY_CURRENT_USER\Software
    • {random}
  • In HKEY_LOCAL_MACHINE\Software
    • {random}

Step 5

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

[ Learn More ]
    • 127.0.0.1       localhost
    • 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
"

Step 6

Scan your computer with your Trend Micro product to delete files detected as TSPY_PIRMINAY.B. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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