Analysis by: Joselyn Canuela

ALIASES:

Trojan:Win32/Kovter!rfn (Microsoft), Trojan.Ransomlock.AK (Symantec), Trojan.Win32.Kovter (Ikarus), Trojan.Agent.MSH (Malwarebytes)

 PLATFORM:

Windows

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

  • 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.

  TECHNICAL DETAILS

File Size: 353,840 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 Aug 2015

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 adds the following processes:

  • %System%\verclsid.exe /S /C {7007ACC7-3202-11D1-AAD2-00805FC1270E} /I {000214E6-0000-0000-C000-000000000046} /X 0x401
  • %System%\regsvr32.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following possibly malicious files or file components:

  • %Application Data%\{random characters}\{random characters}.exe
  • %Cookies%\{User Profile}@www.microsoft[1].txt

Autostart Technique

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

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

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\{random}

HKEY_CURRENT_USER\Software\{random}

Download Routine

This Trojan saves the files it downloads using the following names:

  • %User Temp%\WindowsXP-KB968930-x86-ENG.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://download.{BLOCKED}oft.com/download/E/C/E/ECE99583-2003-455D-B681-68DB610B44A4/WindowsXP-KB968930-x86-ENG.exe

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 11.864.04
FIRST VSAPI PATTERN DATE: 19 Aug 2015
VSAPI OPR PATTERN File: 11.865.00
VSAPI OPR PATTERN Date: 20 Aug 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Search and delete this file

[ 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.  
  • %Application Data%\{random characters}\{random characters}.exe
  • %Cookies%\{User Profile}@www.microsoft[1].txt
  • %User Temp%\WindowsXP-KB968930-x86-ENG.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.

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

Step 5

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • {Default} = "%Application Data%\{random characters}\{random characters}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Default} = "%Application Data%\{random characters}\{random characters}.exe"

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_POWELIKS.F. 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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