TROJ_DLOADER.BA

 Analysis by: Anthony Joe Melgarejo

 ALIASES:

Win32/TrojanDownloader.Agent.RQA trojan (ESET), Trojan.Lithium.Capture (ClamAV), BScope.Trojan-Spy.Zbot (VBA32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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

It saves downloaded files into the said created folder. As of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

216,576 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

25 Apr 2013

Payload:

Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan 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 Trojan drops the following non-malicious file:

  • {malware path and file name}.pdf

It creates the following folders:

  • %User Temp%\{0EAUJB-61517-A87S-XAD0AF9}

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

This Trojan drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\adobe_sl.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Download Routine

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

  • http://{BLOCKED}ads.{BLOCKED}s.com/software.htm

It saves downloaded files into the said created folder.

As of this writing, the said sites are inaccessible.

Other Details

This Trojan opens the following files:

  • {malware path and file name}.pdf

It deletes the initially executed copy of itself

NOTES:

It uses an icon for .PDF files.

The PDF file it opens is titled MODSIM World Conference & Expo 2013 to trick users into thinking they are opening a non-malicious .PDF file.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.878.02

FIRST VSAPI PATTERN DATE:

25 Apr 2013

VSAPI OPR PATTERN File:

9.879.00

VSAPI OPR PATTERN Date:

26 Apr 2013

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

Identify and terminate files detected as TROJ_DLOADER.BA

[ 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 3

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\{0EAUJB-61517-A87S-XAD0AF9}

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.
  • {malware path and file name}.pdf

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADER.BA. 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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