Analysis by: Rika Joi Gregorio
ALIASES:

Backdoor:Win32/Simda(Microsoft), Backdoor.Win32.Simda(Ikarus), Win32/Simda.B trojan(Eset)

 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:

  • In the wild: Yes

  OVERVIEW

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: 434,176 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 Mar 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.

Download Routine

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

  • http://{BLOCKED}1.{BLOCKED}main.com/?abbr=RTK&action=download&setupType=umx&setupFileName=process_64.exe

It saves the files it downloads using the following names:

  • %User Temp%\{random}.sys

(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.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}t.{pseudorandom}.com
  • {BLOCKED}e{random digit}.{pseudorandom}.com
  • {BLOCKED}.{BLOCKED}.12.201:80

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.826.03
FIRST VSAPI PATTERN DATE: 30 Mar 2013
VSAPI OPR PATTERN File: 9.827.00
VSAPI OPR PATTERN Date: 31 Mar 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 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.  
  • %User Temp%\{random}.sys

Step 4

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


Did this description help? Tell us how we did.