Analysis by: Patrick Angelo Roderno

ALIASES:

Trojan:Win32/Dynamer!rfn [non_writable_container] (MICROSOFT); Troj/Agent-AYLF (SOPHOS_LITE); Trojan.GenericKD.30322393 (BITDEFENDER)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • 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 deletes itself after execution.

  TECHNICAL DETAILS

File Size: 1,093,120 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 09 Feb 2018
Payload: Drops files

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.

Installation

This Backdoor drops the following files:

  • {Current Directory}\Microsoft.Win32.TaskScheduler.dll

Other System Modifications

This Backdoor deletes the following files:

  • {Current Directory}\Microsoft.Win32.TaskScheduler.dll

Other Details

This Backdoor deletes itself after execution.

It adds the following scheduled tasks:

  • Microsoft_Security_Task
    • Trigger: Daily - every 5 mins for 60 days
      • Action: Start a program - %Application Data%\Microsoft Network\microsoft_network\1.0.0.0\microsoft_network.exe (detected as BKDR_XRAT.KVL)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.168.06
FIRST VSAPI PATTERN DATE: 03 Apr 2018
VSAPI OPR PATTERN File: 14.169.00
VSAPI OPR PATTERN Date: 04 Apr 2018

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

Restart in Safe Mode

[ Learn More ]

Step 4

Identify and terminate files detected as BKDR_XRAT.KVM

[ 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 5

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.
  • %System%\Tasks\Microsoft_Security_Tasks
  • %Application Data%\Microsoft Network\microsoft_network\1.0.0.0\microsoft_network.exe

Step 6

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

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_XRAT.KVM. 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:


Did this description help? Tell us how we did.