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WORM_TOPHOS.BKD

January 01, 2015
 ALIASES:

Downloader-FFF(McAfee), Downloader(Norton), Worm.Win32.Tophos.b (Sunbelt), W32/Dloadr.BJ!tr.dldr(Fortinet), Worm.Win32.Tophos(Ikarus), a variant of Win32/Tophos.J worm(Eset)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This worm 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 the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

1,169,422 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 Dec 2014

Payload:

Connects to URLs/IPs, Downloads files, Drops files

Arrival Details

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Autostart Technique

This worm drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\search.cmd

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Propagation

This worm drops the following copy of itself in all physical and removable drives:

  • {drive}:\Photo.scr

Download Routine

This worm connects to the following website(s) to download and execute a malicious file:

  • http://www.{BLOCKED}est.ru/get.php?search=
  • http://www.{BLOCKED}est.ru/load.php
  • www.{BLOCKED}mplex.ru/start.rar

It saves the files it downloads using the following names:

  • %Application Data%\temp.cmd

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.380.06

FIRST VSAPI PATTERN DATE:

31 Dec 2014

VSAPI OPR PATTERN File:

11.381.00

VSAPI OPR PATTERN Date:

01 Jan 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

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these files

[ 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%\temp.cmd

Step 5

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