HTML_BADEY.A

Trend Micro has flagged this HTML script as noteworthy due to the increased potential for damage, propagation, or both, that it possesses. Specifically, exploits a zero-day vulnerability in IE that could allow remote code execution. This vulnerability exists in an invalid flag reference in several versions of Internet Explorer. Under certain conditions, it is possible to access the invalid flag reference even after an object is deleted. Certain attacks may do this to allow remote code execution.

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

It takes advantage of a software vulnerability to download possibly malicious files. After succesfully exploiting the vulnerability, this malware connects to URLs to possibly download other malicious files. It saves the files it downloads using file name %User Temp%\log.gif, detected as BKDR_BADEY.A.

It decrypts the downloaded file to %User Profile%\Application Data\alg.exe. It then executes this executable file. As a result, malicious routines of the downloaded file is exhibited on the affected system. The downloaded file is then deleted by the malware after execution.

This Trojan may be hosted on a website and run when a user accesses the said website.

Arrival Details

This Trojan may be hosted on a website and run when a user accesses the said website.

Download Routine

This Trojan takes advantage of the following software vulnerabilities to download possibly malicious files:

• Vulnerability in Internet Explorer Could Allow Remote Code Execution

After successfully exploiting the said vulnerability, this malware connects to the following URLs to possibly download other malicious files:

• http://www.{BLOCKED}lub.com/reg/linkbl.gif

It saves the files it downloads using the following names:

• %User Temp%\log.gif - detected as BKDR_BADEY.A

Other Details

This Trojan does the following:

• Decrypts and executes the downloaded file, %User Profile%\Application Data\alg.exe. Doing so executes this malware. As a result, malicious routines of the downloaded file is exhibited on the affected system. The downloaded file is then deleted by this HTML script after execution.

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)