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Backdoor.Win32.COSMOSIS.A

September 07, 2019
 Analysis by: John Donnie Celestre
 ALIASES:

Gen:Heur.Bodegun.8 (BITDEFENDER)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • 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.

  TECHNICAL DETAILS

File Size:

222,208 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Sep 2019

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.

Backdoor Routine

This Backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • ip: 95.{BLOCKED}.{BLOCKED}.2
    socket: 252
    port: 53

Other Details

This Backdoor requires the existence of the following files to properly run:

  • %ALLUSERSPROFILE%\2AFB1370.SN

It does the following:

  • It operates in two modes:
    • - Slave Mode
    • - Loop Mode
    with Slave Mode being the default mode.
  • It displays the following debug strings if error occurs during its routine:
    • Sys()::MyRecv() fail!
    • Sys()::MyConnect() fail!
    • Thread_SubConnection() UnknownType!
    • Session()::MyRecv(dwCmd) InvalidCommand!
    • EnumSession()::WTSQuerySessionInformationA() fail!
    • EnumSession()::WTSEnumerateSessionsA() fail!
    • SwitchSession()::CreateProcessAsUser() fail!
    • SwitchSession()::WTSQueryUserToken() fail!
    • Ftrans()::CreateFile() fail!

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.348.05

FIRST VSAPI PATTERN DATE:

06 Sep 2019

VSAPI OPR PATTERN File:

15.349.00

VSAPI OPR PATTERN Date:

07 Sep 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

Restart in Safe Mode

[ Learn More ]

Step 4

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.  
  • %ALLUSERSPROFILE%\2AFB1370.SN

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.COSMOSIS.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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