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Backdoor.Win32.SHADOWHAMMER.AA

March 27, 2019
 Analysis by: Jay Bradley Nebre
 ALIASES:

Backdoor:Win32/ShadowHammer!dha(Microsoft); Trojan.ShadowHammer.A(Bitdefender)

 PLATFORM:

Windows

 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.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

3,333,936 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

26 Mar 2019

Payload:

Connects to URLs/IPs, Downloads files

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.

Other Details

This Backdoor does the following:

  • The malicious code that loads, decrypts, and executes the shellcode in the resource can be found in a function call just before the "ExitProcess API"
  • The executed shell code does the following:
    • It checks the MAC address of the computer and generates an MD5 hash of it then compares it to a list.
      • if found on the list, the malware downloads from the URL https://{BLOCKED}tfix.com/logo2.jpg?{MD5hash}.
      • if not found, the malware drops, %User Profile%\idx.ini

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.896.05

FIRST VSAPI PATTERN DATE:

26 Mar 2019

VSAPI OPR PATTERN File:

14.897.00

VSAPI OPR PATTERN Date:

27 Mar 2019

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

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.  
  • %UserProfile%\idx.ini

Step 4

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.SHADOWHAMMER.AA. 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 the following Trend Micro Support pages for more information:


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