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Backdoor.Win32.SHELMA.AMC

February 18, 2019
 Analysis by: Noel Anthony Llimos
 ALIASES:

Trojan-Downloader.Win32.Agentb.i (Kaspersky)

 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


This Trojan may be downloaded by other malware/grayware from remote sites.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

4,887,552 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Jan 2019

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

Installation

This Trojan drops the following files:

  • %Program Files%\Common Files\xpwpd.dat
  • {Executed Malware Directory}\wpd.dat ← configuration file for the initiation of scanning of ports and services
  • {Executed Malware Directory}\csrs.exe ← detected as Trojan.Win32.SHELMA.ANM

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

Backdoor Routine

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

  • Scan ports
  • Execute Shell Commands
  • Download and Execute a Malicious File

It connects to the following websites to send and receive information:

  • 45.{BLOCKED}.106
  • 66.{BLOCKED}.174

Other Details

This Trojan connects to the following URL(s) to get the affected system's IP address:

  • ip.seeip.org

It does the following:

  • Brute force Telnet and MSSQL Server by using a dictionary of weak passwords

It executes the following command to disable/stop/delete Windows components:

  • sc stop netprofm
  • sc config netprofm start= disabled
  • sc stop NaSvc
  • sc config NlaSvc start= disabled
  • net stop WinNsaSrv
  • sc config WinNsaSrv start= disabled
  • sc stop 1MpsSvc
  • sc config 1MpsSvc start= disabled

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.744.04

FIRST VSAPI PATTERN DATE:

11 Jan 2019

VSAPI OPR PATTERN File:

14.745.00

VSAPI OPR PATTERN Date:

12 Jan 2019

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

Search and delete this file

[ 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.  
  • %Program Files%\Common Files\xpwpd.dat
  • {Executed Malware Directory}\wpd.dat ← configuration file for the initiation of scanning of ports and services
  • {Executed Malware Directory}\csrs.exe ← detected as Trojan.Win32.SHELMA.ANM

Step 4

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.SHELMA.AMC. 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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