An exploit for a vulnerability that affects all versions of Internet Explorer and has yet to be patched by Microsoft has been integrated into the open-source Metasploit penetration testing tool, a move that might spur an increasing number of attacks targeting the flaw.

The vulnerability is known as CVE-2013-3893 and was announced by Microsoft on Sept. 17 after the company became aware of its use in targeted attacks. The company released a temporary “Fix It” tool that customers can download and install to address the flaw, but no permanent patch has been released through Windows Update.

The vulnerability affects all versions of Internet Explorer and can be exploited to execute arbitrary code on computers when IE users visit a specially crafted Web page hosted on a malicious or compromised website.

Security researchers have issued warnings about ongoing attack campaigns that have been using the vulnerability to target organizations in Japan and Taiwan since late August or even July, according to some reports.

Since August 29, when an exploit for this vulnerability was first detected as part of an attack dubbed “Operation DeputyDog,” the exploit was adopted by at least two more APT (advanced-persistent-threat) groups and used in targeted attacks, according to a new report by researchers from security firm FireEye.

On Monday, exploit developer and Metasploit contributor Wei Chen released a CVE-2013-3893 exploit module for the popular penetration-testing tool. Chen noted that the module is based on the exploit code that’s already being used by attackers.

The inclusion of the exploit in Metasploit is significant, because while this tool is primarily aimed at security professionals, cybercriminals have made a habit of borrowing exploits from it and using them in their own attacks.

“As long as cybercriminals get access to the exploit code made publicly available we will see instances of the exploit being use by regular cybercriminals and probably we will find the exploit in some of the most famous Exploit Kits,” said Jaime Blasco, manager of the research team at security firm AlienVault, Saturday via email. “I’m sure if Metasploit includes this exploit we will see an increase on widespread exploitation.”

PCWorld