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BKDR_POISON.SMF

May 13, 2013
 Analysis by: Rhena Inocencio
 ALIASES:

Backdoor:Win32/Poison.E (Microsoft), Backdoor.Win32.Poison.fism (Kaspersky), Win32/Poison.TMW trojan (NOD32)

 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:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This backdoor 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 commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It logs a user's keystrokes to steal information.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 May 2013

Payload:

Steals information, Compromises system security

Arrival Details

This backdoor 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 backdoor drops the following files:

  • %System%\ns{number}dos - contains logged keystrokes on active windows

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It drops the following copies of itself into the affected system:

  • %System%\ns{number}dos.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

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

  • )!GmvD.P4
  • )!gNCfhT7
  • )!UfMfsv7

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{CLSID}
StubPath = "%System%\ns{number}dos.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
msdos-debug{number or letter} = "%System%\ns{number}dos.exe"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Manage files, registry, processes, services, devices, and installed applications
  • Download and inject remote codes to legitimate processes
  • Capture screenshots, webcam and audio
  • Log keystrokes and active window
  • Manage open windows
  • Perform remote shell
  • Relay server
  • Retrieve cached passwords and hashes
  • Send hardware information (CPU speed, Memory)
  • Send system information (LAN IP, WAN IP, Computer name, User name, Account Type, OS)
  • Update, Uninstall, Restart the malware
  • View active ports

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

  • {BLOCKED}.{BLOCKED}.37.90:80
  • {BLOCKED}.{BLOCKED}.35.101:80
  • {BLOCKED}.{BLOCKED}.35.102:80

Information Theft

This backdoor logs a user's keystrokes to steal information.

Other Details

This backdoor deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

7.844.14

FIRST VSAPI PATTERN DATE:

18 Feb 2011

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.

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  • msdos-debug{number or letter}="%System%\ns{number}dos.exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{CLSID}
  • StubPath="%System%\ns{number}dos.exe"

Step 4

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.
  • %System%\ns{number}dos

Step 5

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