Trojan:Win32/Kovter.C (Microsoft), Win32/Kovter.A (ESET)




  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel:

Dropped by other malware, Downloaded from the Internet

This malware is the payload of the attack related to YouTube ads that lead to Sweet Orange exploit kit.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

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 modifies the Internet Explorer Zone Settings.

It connects to certain websites to send and receive information.


File Size:


File Type:


Memory Resident:


Initial Samples Received Date:

10 Oct 2014


Steals information, Connects to URLs/IPs

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.


This Trojan adds the following processes:

  • svchost.exe

It injects codes into the following process(es):

  • svchost.exe

Other System Modifications

This Trojan adds the following registry entries:

Internet Explorer\Main\FeatureControl\
svchost.exe = "1"

Internet Explorer\Main\FeatureControl\
svchost.exe = "1"

(Default) = "1"

Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}
  • http://{BLOCKED}
  • http://{BLOCKED}
    • posts the following information: mode={mode}&UID={uid}&OS={OS version}&OSbit={OS architecture}&aff_id={id}&oslang={language}&gmt={GMT}&antidetect={summary of AV-related application}


As of this writing, there is no response from the servers.

It does not perform its intended routine if the following files are found:

  • a2guard.exe
  • a2service.exe
  • avas.exe
  • avcom.exe
  • avp.exe
  • avss.exe
  • bdagent.exe
  • BullGuard.exe
  • cistray.exe
  • cmdagent.exe
  • dwengine.exe
  • dwservice.exe
  • jpf.exe
  • jpfsrv.exe
  • oasrv.exe
  • oaui.exe
  • op_mon.exe

It gathers the following data:

  • UID
  • OS version
  • OS architecture (32bit/64bit)
  • Default language
  • GMT
  • Summary of installed AV-related applications

It queries the value of the following registry entry:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion


Minimum Scan Engine:


Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Scan your computer with your Trend Micro product and note files detected as TROJ_KOVTER.SM

Step 3

Restart in Safe Mode

[ Learn More ]

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\Internet Explorer\Main\FeatureControl\FEATURE_BLOCK_INPUT_PROMPTS
    • svchost.exe = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_AJAX_CONNECTIONEVENTS
    • svchost.exe = "1"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\policies\Ratings
    • (Default) = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • GlobalUserOffline = "0"

Step 5

Search and delete the file detected as TROJ_KOVTER.SM

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 6

Reset Internet security settings

[ Learn More ]

Step 7

Reset Internet privacy settings

[ Learn More ]

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_KOVTER.SM. 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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