Analysis by: Karl Dominguez


Windows 2000, Windows XP, Windows Server 2003


  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


This Trojan may be dropped by other malware.

It deletes the initially executed copy of itself.


File Size: 72,704 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 16 Sep 2011
Payload: Modifies system registry, Drops files

Arrival Details

This Trojan may be dropped by the following malware:



This Trojan drops the following files:

  • %User Profile%\Application Data\Adobe\Acrobat_sl.exe - BKDR_DEMTRANC.DK

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It drops the following copies of itself into the affected system:

  • %User Temp%\Del{random number}.tmp

(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.)

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

Acrobat Updater = "%User Profile%\Application Data\Adobe\Acrobat_sl.exe"

Other System Modifications

This Trojan adds the following registry entries:

.dll = "{blank}"

Other Details

This Trojan deletes the initially executed copy of itself


Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 8.437.00
VSAPI OPR PATTERN Date: 19 Sep 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

Remove the malware/grayware file that dropped/downloaded TROJ_DROPPER.QUB

Step 3

Remove malware/grayware files dropped/downloaded by TROJ_DROPPER.QUB

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Acrobat Updater = "%User Profile%\Application Data\Adobe\Acrobat_sl.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • .dll = "{blank}"

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.QUB. 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.

Did this description help? Tell us how we did.