Modified by: RonJay Kristoffer Caragay
ALIASES:

TrojanDownloader:Win32/Cutwail.BF (Microsoft); Trojan.Pandex (Symantec); HEUR:Trojan.Win32.Generic (Kaspersky); MemScan:Trojan.Cutwail.AP (B) (Emsisoft)

 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:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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 may be dropped by other malware.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible. It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 28,160 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Aug 2014
Payload: Connects to URLs/IPs, 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.

It may be dropped by the following malware:

Installation

This Trojan drops a copy of itself in the following folders using different file names:

  • %System%\{random filename}.exe
  • %User Profile%\{random filename}.exe

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

It adds the following processes:

  • svchost.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • CTR.{random value}

It injects itself into the following processes as part of its memory residency routine:

  • created svchost.exe

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
{random filename} = "%System%\{random filename}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = "%User Profile%\{random filename}.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\WinNTData
prx = "{hex values}"

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • yahoo.com
  • hotmail.com
  • gmail.com
  • aol.com
  • web.de

It connects to the following website to send and receive information:

  • {BLOCKED}.{BLOCKED}.90.125:443
  • {BLOCKED}.{BLOCKED}.172.129:443
  • {BLOCKED}.{BLOCKED}.104.81:443
  • {BLOCKED}.{BLOCKED}.94.182:443
  • {BLOCKED}.{BLOCKED}.198.93:443
  • {BLOCKED}.{BLOCKED}.33.125:443
  • {BLOCKED}.{BLOCKED}.36.184:443

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

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.924.09
FIRST VSAPI PATTERN DATE: 15 Jul 2014
VSAPI OPR PATTERN File: 10.925.00
VSAPI OPR PATTERN Date: 16 Jul 2014

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

Remove the malware/grayware file that dropped/downloaded TROJ_CUTWAIL.IVF. (Note: Please skip this step if the threat(s) listed below have already been removed.)

Step 4

Restart in Safe Mode

[ Learn More ]

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\WinNTData
    • prx = "{hex values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random filename} = "%System%\{random filename}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random filename} = "%User Profile%\{random filename}.exe"

Step 6

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