Virus Profile: JS/!htm

Threat Search
Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 6/12/2012
Date Added: 6/12/2012
Origin: N/A
Length: Varies
Type: Trojan
Subtype: Exploit
DAT Required: N/A
Removal Instructions


This is a Trojan detection. Unlike viruses, Trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include e-mail, malicious or hacked Web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.


  • Avast         - JS:Downloader-BOF [Trj]
  • Kaspersky - Trojan-Downloader.JS.Expack.rv
  • NOD32     - JS/Kryptik.PH
  • Microsoft   - Exploit:JS/Blacole.GB

Indication of Infection

Because this is a generic detection there is no specific description of the activity undertaken by JavaScript detected under this name, however these can include malicious activity such as downloading and executing files or scripts.

Methods of Infection

Trojans do not self-replicate. They are spread manually, often under the premise that the executable is something beneficial. Distribution channels include IRC, peer-to-peer networks, newsgroup postings, e-mail, etc.

Virus Characteristics

JS/!htm” is the detection for malicious JavaScript that loads other exploits. The Obfuscated JavaScript covers the recent exploits which infiltrate the victim’s machine by exploiting vulnerabilities to download the malicious files from the remote servers.
The infection may occur when user visits the compromised website which is hosted with malicious JavaScript by the Blackhole exploit kit.

Upon execution, the Trojan downloads the malicious applet archive from the below mentioned URL:

  • hxxp://th[Removed]an .com/set.jar

At the time of writing the VIL Description, the content of the JAR Archive is not available.

The main characteristics of this Trojan are checking for a bunch of components on the system and start eventually loading an applet to load a jar file with the blacole classes.


All Users:
Use current engine and DAT files for detection and removal.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).


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