Analysis by: Jay Garcia
ALIASES:

VirTool:Win32/Atosev.A (Microsoft); a variant of Win32/Rozena.AEV trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

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 does not have any propagation routine.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size: 410,208 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 22 Jul 2019
Payload: Connects to URLs/IPs

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.

Propagation

This Backdoor does not have any propagation routine.

Rootkit Capabilities

This Backdoor does not have rootkit capabilities.

Information Theft

This Backdoor does not have any information-stealing capability.

Other Details

This Backdoor does the following:

  • It connects to the following URL to download backdoor modules:
    • http://{random numbers}.api.{BLOCKED}-internal.com/stats/start-session?s_iv={value}

NOTES:

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

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.250.06
FIRST VSAPI PATTERN DATE: 22 Jul 2019
VSAPI OPR PATTERN File: 15.251.00
VSAPI OPR PATTERN Date: 23 Jul 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

Identify and terminate files detected as Backdoor.Win32.COBALT.AI

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.COBALT.AI. 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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