Analysis by: Wilbert Vidal
 Modified by: Michael Jhon Ofiaza
ALIASES:

Trojan-Ransom.MSIL.Samas.bz (Kaspersky) ; Ransom:MSIL/SamSam.D!dr (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

This Trojan 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: 6,656 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 11 Dec 2017
Payload: Deletes files

Arrival Details

This Trojan 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 Trojan does the following:

  • Searches for the .stubbin file present in the current directory of the malware
  • Reads the .stubbin file, decrypts it, and executes it, passing the remaining arguments of the malware
  • Deletes the .stubbin file
  • If the malware is run with the number of its arguments not equal to three, the malware terminates

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.838.08
FIRST VSAPI PATTERN DATE: 12 Dec 2017
VSAPI OPR PATTERN File: 13.839.00
VSAPI OPR PATTERN Date: 13 Dec 2017

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

Scan your computer with your Trend Micro product to delete files detected as TROJ_RUNNER.GAX. 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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