ALIASES:

Backdoor:Win32/Small.A (Microsoft); W32.Whybo.Z (Symantec); Trojan-Dropper.Win32.Agent.uor (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse BackDoor.Generic9.ATSY.dropper (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 11,776 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 15 May 2013

Arrival Details

This spyware 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 spyware drops the following copies of itself into the affected system:

  • %System%\darkshell.exe

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

Other System Modifications

This spyware modifies the following file(s):

  • %System%\drivers\beep.sys

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

It deletes the following files:

  • %System%\drivers\beep.sys
  • %System%\darkshell.exe

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

Dropping Routine

This spyware drops the following files:

  • %System%\ds.vbs

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

Other Details

This spyware connects to the following possibly malicious URL:

  • http://www.{BLOCKED}ell.com/ip.jpg

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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

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%\ds.vbs

Step 3

Scan your computer with your Trend Micro product to delete files detected as TSPY_LEGMIR.CZA. 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.

Step 4

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %System%\drivers\beep.sys

Step 5

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System%\drivers\beep.sys
  • %System%\darkshell.exe


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