Malware type: Trojan

In the wild: No

Language: English

Overall risk rating:

Reported infections:

Damage potential:


Distribution potential:



A Trojan horse program is a malware that is not capable of automatically spreading to other systems. Trojans are usually downloaded from the Internet and installed by unsuspecting users.

Trojans typically carry payloads or other malicious actions that can range from the mildly annoying to the irreparably destructive. They may also modify system settings to automatically start. Restoring affected systems may require procedures other than scanning with an antivirus program.

For additional information about this threat, see:


File type: PE

Memory resident:  Yes

Size of malware: 102,068 Bytes



This Trojan drops the following copy(ies) of itself:

  • %System%\uspzs.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003. )

Other System Modifications

This Trojan creates the following registry key(s)/entry(ies):

Internet Explorer\Main
TabProcGrowth = "0"

SystemMgr = "Del"

Affected Platforms

This Trojan runs on Windows 98, ME, NT, 2000, XP, Server 2003.

Revision History:

First pattern file version: 7.340.17
First pattern file release date: Jul 27, 2010


Pattern file needed: 7.619.00

Pattern release date: Nov 13, 2010


For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

 Step 1: Identify and terminate files detected as TROJ_MEREDROP.QO  [learn how]


  1. For Windows 98 and ME users, 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 2:  Delete this registry value  [learn how]

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.

    Internet Explorer\Main
    • TabProcGrowth = "0"
    • SystemMgr = "Del"

 Step 3:  Search and delete these files  [learn how]

*Note: There may be some component files that are hidden. Please make sure you uncheck Hide protected operating system files in Folders Option>View tab, and then 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.

  • %System%\uspzs.exe

 Step 4: Scan your computer with your Trend Micro product to delete files detected as TROJ_MEREDROP.QO  

*Note: 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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