TROJ_RANSOM.CMY

October 09, 2012
 Analysis by: Christopher Daniel So
 ALIASES:

Generic.dx!bf3t (McAfee), Trojan-Ransom.Win32.PornoAsset.acal (Kaspersky), Mal/Ransom-Z (Sophos), Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

This Trojan may be downloaded by other malware/grayware from remote sites.

  TECHNICAL DETAILS

File Size:

66,048 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

27 Sep 2012

Payload:

Displays ransom message, Terminates processes

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • PE_QUERVAR.E-O

It may be downloaded from the following remote site(s):

  • http://{BLOCKED}0.com/c/osnovnoj2.exe?{random number}

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
(Default) = "{malware path and file name}"

(Note: The default value data of the said registry entry is {blank}.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • cmd.exe
  • msconfig.exe
  • regedit.exe
  • taskmgr.exe

NOTES:

It removes the taskbar.

It accesses the following URL to display the ransom message:

  • http://{random characters}.unionfilesexchnges.su/get.php?id=2 - detected by Trend Micro as HTML_RANSOM.CMY

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.428.05

FIRST VSAPI PATTERN DATE:

29 Sep 2012

VSAPI OPR PATTERN File:

9.429.00

VSAPI OPR PATTERN Date:

29 Sep 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove the malware/grayware file that dropped/downloaded TROJ_RANSOM.CMY

Step 3

Remove malware files dropped/downloaded by TROJ_RANSOM.CMY

Step 4

Since this malware uses rootkit technology, detection and removal using normal and safe mode methods may not eliminate it completely. This procedure restarts the system using the Windows Recovery Console.

  1. Insert the Windows Installation CD into the CD drive, then Press the restart button.
  2. Upon prompt, press any key to boot from the CD.
  3. On the main menu, type r to go to the Recovery Console.
  4. Type the drive that contains Windows (usually C:) and press Enter.
  5. In the input box, type the following then press Enter:
    ren explorer.exe explorer.tmp
    copy system32\cmd.exe explorer.exe
  6. Type exit and press Enter to restart the system normally.

Step 5

Restore this modified 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
    • From: (Default) = "{malware path and file name}"
      To: (Default) = ""

Step 6

Restoring Deleted Registry Keys

  1. Still in Registry Editor, in the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>
    Control>SafeBoot>Minimal
  2. Right-click on the key and choose New>Key. Change the value of the new key to:
    {4D36E967-E325-11CE-BFC1-08002BE10318}
  3. Right-click on the value name and choose Modify. Change the value data of this entry to:
    DiskDrive
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>
    Control>SafeBoot>Network
  5. Right-click on the key and choose New>Key. Change the value of the new key to:
    {4D36E967-E325-11CE-BFC1-08002BE10318}
  6. Right-click on the value name and choose Modify. Change the value data of this entry to:
    DiskDrive
  7. Close Registry Editor.

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.CMY. 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.

NOTES:

Before performing step 3, do the following step:

Upon starting the system from Recovery Console, a command prompt window appears instead of the taskbar. In the command prompt window, type the following:

regedit & start cmd & exit

This opens the Registry Editor and another command prompt window while closing the first one.

After performing step 3, type the following in the command prompt window:

cd C:\WINDOWS
del explorer.exe
ren explorer.tmp explorer.exe
explorer
exit


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