Analysis by: Erika Bianca Mendoza


TR/Spy.13540 (Antivir)


Windows 2000, Windows XP, Windows Server 2003


  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes


This backdoor may be dropped by TROJ_DROPPER.ADO.

When executed, it executes commands from a remote malicious user to start or stop services, list processes and services, get system information and download files.

It executes commands from a remote malicious user, effectively compromising the affected system.

It retrieves specific information from the affected system.

This backdoor may be dropped by other malware.


Ports: TCP Port 443
File Size: 14,792 bytes
File Type: PE
File Compression: UPX
Initial Samples Received Date: 14 Mar 2011
Payload: Steals information

Arrival Details

This backdoor may be dropped by the following malware:



This backdoor is injected into the following processes running in memory:



Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download files
  • Get system information
  • List processes and services
  • Start or stop services

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


Information Theft

This backdoor retrieves the following information from the affected system:

  • CPU
  • Disk space
  • Drive information
  • File/Folder list
  • Operating system
  • Process/Service list


Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 7.905.00
VSAPI OPR PATTERN Date: 15 Mar 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Scan your computer with your Trend Micro product and note files detected as BKDR_COSMU.KO

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as BKDR_COSMU.KO

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_COSMU.KO. 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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