Attackers exploited ColdFusion vulnerability to install Microsoft IIS malware

The malware works as an IIS module and can capture data entered by users in Web forms

Attackers exploited a vulnerability in Adobe ColdFusion to install data-stealing malware that works as a module for Microsoft's Internet Information Services (IIS) Web server software.

Researchers from security firm Trustwave recently reported they've identified IIS (Internet Information Server) Web servers infected with malicious IIS modules designed to steal information submitted by users on websites hosted on those servers.

The modules are rogue DLL (dynamic link library) files and were installed by a malware program the Trustwave researchers dubbed ISN that infects both 32-bit and 64-bit versions of IIS6 and IIS7+.

ISN detects the IIS version and installs the corresponding DLL module, which then monitors POST requests -- data submissions -- to specific URLs and saves the information to a log file.

This method allows the data to be collected even if the connection between the user and the server is protected by SSL (Secure Sockets Layer). The captured data can be, for example, personal and payment details entered on an e-commerce site running on a compromised IIS server. The rogue DLLs also enables attackers to send certain commands through URL parameters in order to download the stored information.

In a new blog post Friday, the researchers revealed that ISN is being installed on the compromised IIS servers by exploiting a remote authentication bypass vulnerability in Adobe ColdFusion, a Web application platform.

Adobe released a patch for the vulnerability, identified as CVE-2013-0629, back in January, a few weeks after warning customers that the vulnerability was being actively exploited in attacks.

In this case, the attackers are exploiting CVE-2013-0629 to install a backdoor application called a Web shell that allows them to execute shell commands on the underlying operating system.

The Trustwave researchers traced such a ColdFusion compromise that led to the installation of ISN back to the end of February, over a month after Adobe issued its patch. "In this particular incident, the victim organization was aware of the vulnerability report by Adobe, however they were on a quarterly patching process and had not yet installed the patch," the Trustwave researchers said.

The incident outlines a problem many organizations have when it comes adjusting their patching schedules to keep up with today's attackers who are targeting newly disclosed vulnerabilities much faster than in previous years.

It also shows that ColdFusion represents an interesting target for attackers. Adobe warned customers two times this year about ColdFusion vulnerabilities that had no patches and were already being actively exploited by attackers. In April hackers broke into the management servers and customer database of Linode, a virtual private server hosting firm, by exploiting a previously unknown ColdFusion vulnerability.

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