BKDR64_TDSS.JS

 Analysis by: Alvin Bacani

 PLATFORM:

Windows XP (64-bit), Windows Vista (64-bit), Windows 7 (64-bit)

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

  • 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 lowers the security setting of Internet Explorer.

  TECHNICAL DETAILS

File Size:

53,248 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Nov 2013

Payload:

Connects to URLs/IPs, 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 component file(s):

  • "%User Temp%\{random folder name}\{random folder name}\wow.dll" - detected as BKDR64_TDSS.JS

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

It drops the following non-malicious file:

  • "%User Temp%\{random folder name}\{random folder name}\wow.ini"

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

It creates the following folders:

  • %User Temp%\{random folder name}\{random folder name}

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

Autostart Technique

This backdoor modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_CLASSES_ROOT\CLSID\{fbeb8a05-beee-4442-804e-409d6c4515e9}\
InProcServer32
[Default] = "%User Temp%\{random folder name}\{random folder name}\wow.dll"

(Note: The default value data of the said registry entry is "%System%\SHELL32.dll.)

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Classes\
clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}\inprocserver32
[Default] = "%User Temp%\{random folder name}\{random folder name}\wow.dll"

Web Browser Home Page and Search Page Modification

This backdoor lowers the security setting of Internet Explorer.

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}r.com
  • {BLOCKED}k.com
  • {BLOCKED}e.com
  • {BLOCKED}z.com
  • {BLOCKED}.{BLOCKED}.232.20

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.404.08

FIRST VSAPI PATTERN DATE:

11 Nov 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

Identify and delete files detected as BKDR64_TDSS.JS using either the Startup Disk or Recovery Console

[ 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\Software\Classes\clsid\{fbeb8a05-beee-4442-804e-409d6c4515e9}\inprocserver32
    • [Default] = "%User Temp%\{random folder name}\{random folder name}\wow.dll"

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_CLASSES_ROOT\CLSID\{fbeb8a05-beee-4442-804e-409d6c4515e9}\InProcServer32
    • From: [Default] = "%User Temp%\{random folder name }\{random folder name}\wow.dll"
      To: [Default] = "%System%\SHELL32.dll"

Step 5

Reset Internet security settings

[ Learn More ]

Step 6

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.  
  • %User Temp%\{random folder name}\{random folder name}

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR64_TDSS.JS. 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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