TROJ_RANSOM.SMJA

November 22, 2012
 Analysis by: Mark Joseph Manahan
 ALIASES:

Trojan:Win32/Reveton.F (Microsoft), Win32/Reveton.H trojan (Eset), Trojan.Ransomlock.G (Symantec)

 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, Dropped by other malware

This Trojan is a ransomware using fake digital certificates to avoid digital signing checks.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

For the related story, you may read the blog post Ransomware Bears Fake Digital Signature

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 modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

19 Nov 2012

Payload:

Terminates processes, Compromises system security

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 the following component file(s):

  • {All User's Profile}\lsass.exe - Normal
  • {All User's Profile}\{random}.pad

It injects codes into the following process(es):

  • IEXPLORE.EXE
  • IESTART.EXE
  • FIREFOX.EXE
  • OPERA.EXE
  • CHROME.EXE

Autostart Technique

This Trojan drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:

  • ctfmon.lnk

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
0
2500 = "3"

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
1
2500 = "3"

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
2
2500 = "3"

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
3
2500 = "3"

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
4
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Internet\Explorer\Main
NoProtectedBanner = "1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
0
1609 = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
1
1609 = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
2
1609 = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
3
1609 = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Microsoft\Windows\
CurrentVersion\Internet Settings\Zones\
4
1609 = "0"

(Note: The default value data of the said registry entry is 1.)

Process Termination

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

  • taskmgr.exe

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan connects to the following website to send and receive information:

  • {BLOCKED}llber.com

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.536.03

FIRST VSAPI PATTERN DATE:

19 Nov 2012

VSAPI OPR PATTERN File:

9.537.00

VSAPI OPR PATTERN Date:

20 Nov 2012

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\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet\Explorer\Main
    • NoProtectedBanner = "1"

Step 4

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\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
    • From: 1609 = "0"
      To: 1609 = "1"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
    • From: 1609 = "0"
      To: 1609 = "1"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
    • From: 1609 = "0"
      To: 1609 = "1"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • From: 1609 = "0"
      To: 1609 = "1"
  • In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4
    • From: 1609 = "0"
      To: 1609 = "1"

Step 5

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • {All User's Profile}\lsass.exe
  • {All User's Profile}{random}.pad
  • %User Startup%\ctfmon.lnk

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_RANSOM.SMJA. 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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