Analysis by: Roland Marco Dela Paz


Symantec : Trojan.ADH; Microsoft : Trojan:Win32/Meredrop


Windows 2000, XP, Server 2003


  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


File Size: Varies
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 08 Jan 2011


This Trojan drops and executes the following files:

  • %Program Files%\Internet Explorer\setupapi.dll - detected as TROJ_DLOAD.QKLW

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

Autostart Technique

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

Control\Session Manager\AppCertDlls
DefaultVerifier = %Program Files%\Internet Explorer\setupapi.dll


Minimum Scan Engine: 8.900
VSAPI PATTERN File: 07.754.05
VSAPI PATTERN Date: 08 Jan 2011
VSAPI PATTERN Date: 1/8/2011 12:00:00 AM

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 malware files dropped/downloaded by TROJ_MEREDROP.TG

Step 3

Delete this registry key

[ 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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager
    • AppCertDlls

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_MEREDROP.TG. 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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