Analysis by: Johnlery Triunfante
ALIASES:

Trojan.BAT.Yossi.a (KASPERSKY); Mal/Carbanak-A (SOPHOS_LITE)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

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

  TECHNICAL DETAILS

File Size: 6,054 bytes
File Type: PS1
Memory Resident: No
Initial Samples Received Date: 07 Jul 2017
Payload: Connects to URLs/IPs

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:

  • It executes the following command:
    • powershell.exe -nop -w -hidden -encodedcommand {malicious encrypted code}
  • It executes arbitrary code via DNS message.

It performs DNS requests to the following sites:

  • aaa.{BLOCKED}e.3991775.en.{BLOCKED}4-ssl.com

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

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.518.08
FIRST VSAPI PATTERN DATE: 07 Jul 2017
VSAPI OPR PATTERN File: 13.519.00
VSAPI OPR PATTERN Date: 08 Jul 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_DOBESY.A. 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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