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BKDR_SIMDA.UHU

October 17, 2014
 ALIASES:

TrojanDownloader:Win32/Cutwail.BF (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

132,096 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Oct 2014

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 copies of itself into the affected system:

  • %System%\{random filename}.exe
  • %User Profile%\{random filename}.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %User Profile% is a user's profile folder, where it usually is C:\Documents and Settings\{user name} on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name} 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 adds the following processes:

  • svchost.exe

It injects codes into the following process(es):

  • svchost.exe

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = "%System%\{random filename}.exe"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download a file
  • Execute a file
  • Execute CMD
  • Inject file to a running process

It connects to the following websites to send and receive information:

  • {BLOCKED}1.{BLOCKED}6.212.179:443
  • {BLOCKED}5.{BLOCKED}1.161.13:443
  • {BLOCKED}3.{BLOCKED}9.86.151:443
  • {BLOCKED}5.{BLOCKED}5.208.192:443
  • {BLOCKED}1.{BLOCKED}7.198.93:443
  • {BLOCKED}6.{BLOCKED}1.200.70:443
  • {BLOCKED}3.{BLOCKED}9.68.82:443

Information Theft

This backdoor gathers the following data:

  • Processor information
  • Country
  • OS Version

Other Details

This backdoor deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.214.05

FIRST VSAPI PATTERN DATE:

15 Oct 2014

VSAPI OPR PATTERN File:

11.215.00

VSAPI OPR PATTERN Date:

15 Oct 2014

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

Scan your computer with your Trend Micro product and note files detected as BKDR_SIMDA.UHU

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • {random filename} = "%System%\{random filename}.exe"

Step 5

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