Monthly Threat Report: April 2012

1. HTML/ScrInject.B

Previous Ranking: 1
Percentage Detected: 6.75%

Generic detection of HTML web pages containing script obfuscated or iframe tags that that automatically redirect to the malware download.

2. HTML/Iframe.B

Previous Ranking: 3
Percentage Detected: 4.54%

Type of infiltration: Virus
HTML/Iframe.B is generic detection of malicious IFRAME tags embedded in HTML pages, which redirect the browser to a specific URL location with malicious software.

3. INF/Autorun

Previous Ranking: 2
Percentage Detected: 4.32%

This detection label is used to describe a variety of malware using the file autorun.inf as a way of compromising a PC. This file contains information on programs meant to run automatically when removable media (often USB flash drives and similar devices) are accessed by a Windows PC user. ESET security software heuristically identifies malware that installs or modifies autorun.inf files as INF/Autorun unless it is identified as a member of a specific malware family.

Removable devices are useful and very popular: of course, malware authors are well aware of this, as INF/Autorun’s frequent return to the number one spot clearly indicates. Here’s why it’s a problem.

The default Autorun setting in Windows will automatically run a program listed in the autorun.inf file when you access many kinds of removable media. There are many types of malware that copy themselves to removable storage devices: while this isn’t always the program’s primary distribution mechanism, malware authors are always ready to build in a little extra “value” by including an additional infection technique.

While using this mechanism can make it easy to spot for a scanner that uses this heuristic, it’s better, as Randy Abrams has suggested in our blog ( ; to disable the Autorun function by default, rather than to rely on antivirus to detect it in every case. You may find Randy’s blog at useful, too.

4. JS/Iframe.AS

Previous Ranking: 6
Percentage Detected: 4.14%

JS/Iframe.AS is a trojan that redirects the browser to a specific URL location with malicious software. The program code of the malware is usually embedded in HTML pages.

5. Win32/Conficker

Previous Ranking:  4
Percentage Detected: 2.86%

The Win32/Conficker threat is a network worm originally propagated by exploiting a recent vulnerability in the Windows operating system. This vulnerability is present in the RPC sub-system and can be remotely exploited by an attacker without valid user credentials. Depending on the variant, it may also spread via unsecured shared folders and by removable media, making use of the Autorun facility enabled at present by default in Windows (though not in Windows 7).

Win32/Conficker loads a DLL through the svchost process. This threat contacts web servers with pre-computed domain names to download additional malicious components. Fuller descriptions of Conficker variants are available at

While ESET has effective detection for Conficker, it’s important for end users to ensure that their systems are updated with the Microsoft patch, which has been available since the third quarter of 2008, so as to avoid other threats using the same vulnerability. Information on the vulnerability itself is available at While later variants dropped the code for infecting via Autorun, it can’t hurt to disable it: this will reduce the impact of the many threats we detect as INF/Autorun. The Research team in San Diego has blogged extensively on Conficker issues:

It’s important to note that it’s possible to avoid most Conficker infection risks generically, by practicing “safe hex”: keep up-to-date with system patches, disable Autorun, and don’t use unsecured shared folders. In view of all the publicity Conficker has received and its extensive use of a vulnerability that’s been remediable for so many months, we’d expect Conficker infections to be in decline by now if people were taking these commonsense precautions. While the current ranking looks like a drop in Conficker prevalence, this figure is affected by the changes in naming and statistical measurement mentioned earlier: there’s no indication of a significant drop in Conficker infections covering all variants.

6. Win32/Sirefef

Previous Ranking: 7
Percentage Detected: 1.95%

Win32/Sirefef.A is a trojan that redirects results of online search engines to web sites that contain adware.

7. JS/TrojanDownloader.Iframe.NKE

Previous Ranking: 7
Percentage Detected: 1.86%

It is a trojan that redirects the browser to a specific URL location with malicious software. The program code of the malware is usually embedded in HTML pages.

8. JS/Agent

Previous Ranking: 5
Percentage Detected: 1.55%

The trojan displays dialogs that ask the user to purchase a specific product/service. After purchasing the product/service, the malware removes itself from the computer. Trojan is probably a part of other malware.

9. Win32/Dorkbot

Previous Ranking: 9
Percentage Detected: 1.53%

Win32/Dorkbot.A is a worm that spreads via removable media. The worm contains a backdoor. It can be controlled remotely. The file is run-time compressed using UPX.
The worm collects login user names and passwords when the user browses certain web sites. Then, it attempts to send gathered information to a remote machine.  This kind of worm can be controlled remotely.

10. JS/Redirector

Previous Ranking: 10
Percentage Detected: 1.41%

JS/Redirector is a trojan that redirects the browser to a specific URL location with malicious software. The program code of the malware is usually embedded in HTML pages.

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