Analysis by: Adrian Cofreros

 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: Backdoor

  • Destructiveness: No

  • Encrypted:

  • 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.

  TECHNICAL DETAILS

File Size: 2,662,912 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Aug 2013

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 adds the following folders:

  • %Program Files%\Tor
  • %System%\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service
  • %System%\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service\{random numbers}
  • %Root%\Documents and Settings\LocalService\Application Data\tor
  • %Root%\Documents and Settings\LocalService\Application Data\tor\lock
  • %Root%\Documents and Settings\LocalService\Application Data\tor\state

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It drops the following component file(s):

  • %System%\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service\{random numbers}
  • %System32\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service\{random numbers}\{random numbers}.ct
  • %System32\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service\{random numbers}\{random numbers}.ph

(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%\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service\wins.exe

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

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor
ImagePath = "%Program Files%\Tor\tor.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor
DisplayName = "Tor Win32 Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor
ObjectName = "NT AUTHORITY\LocalService"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor
Description = "Provides an anonymous Internet communication system"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
ImagePath = "%System%\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service\wins.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
DisplayName = "Windows Internet Name Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
Group = "netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service
Description = "Provides Internet Name Service"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\tor

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Internet Name Service

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}o.{BLOCKED}1.se
  • {BLOCKED}har.{BLOCKED}i.jp
  • {BLOCKED}116695.{BLOCKED}x.net
  • {BLOCKED}berg.{BLOCKED}c.de
  • {BLOCKED}t-router41-readme.{BLOCKED}ssnetworking.net

NOTES:
This backdoor drops a TOR client %Program Files%\Tor\tor.exe. It uses the following parameters to perform routine:

  • /I - For malware installation(please see above modifications)
  • /R - Register the service
It uses TOR client to for connection to remote user.

The malware will attempt to connect to the following Onion Addresses via TOR Network:

  • {BLOCKED}ktcb3gudt3.onion
  • {BLOCKED}6vxyhpeouy.onion
  • {BLOCKED}n3rrxtknu6.onion
  • {BLOCKED}dixp4qbzce.onion
  • {BLOCKED}ijtdca2tsy.onion
  • {BLOCKED}xqxscsmscx.onion
  • {BLOCKED}wa5yzxewc3.onion
  • {BLOCKED}gagyod22sc.onion
  • {BLOCKED}g64gi6fk7b.onion
  • {BLOCKED}foqy4acjv4.onion
  • {BLOCKED}sfnmtn544p.onion
  • {BLOCKED}24mj7m4e2o.onion
  • {BLOCKED}2omakx655w.onion
  • {BLOCKED}qbnm6vctar.onion

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.260.04
FIRST VSAPI PATTERN DATE: 28 Aug 2013
VSAPI OPR PATTERN File: 10.261.00
VSAPI OPR PATTERN Date: 29 Aug 2013

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

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Program Files%\Tor
  • %System%\config\systemprofile\Local Settings\Application Data\Windows Internet Name Service
  • %Root%\Documents and Settings\LocalService\Application Data\tor

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.

 
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • tor
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Windows Internet Name Service

Step 5

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