Second Lifers, Run for Cover

A security researcher has outlined six easy steps to exploit an Internet Explorer flaw to steal a Second Life members log-in credentials and hijack their virtual persona simply by tricking the victim into visiting a rigged Web page.

The researcher, Petko D. Petkov—aka pdp—initially said hed rate the issue as medium risk unless the victim has a lot of virtual cash, known as Linden dollars ($L). "Then the situation becomes quite critical," he said in a Sept. 16 posting. At the time he posted, he said that $1 could be exchanged for $268.15L; Second Life says on its currency exchange site that over the last few years the rate has remained "fairly stable" at about 250 Linden dollars to one U.S. dollar.

Given the potential profit, and given that victims dont have to interact with the evil scripts involved outside of their initial visit to the rigged site, Petkov decided to kick the risk level up a notch. "Now when I am thinking about it, this issue should be really highlighted as HIGH risk, since no interaction is required from the user," he said later in the post.

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Heres how it works: When a victim visits a maliciously crafted site, the Second Life client launches and tries to automatically log in via a malicious CGI script. An XML-RPC remote call is then generated to the CGI script to sniff out user credentials and a hash of the victims password.

The fact that the users password is hashed is "completely pointless," Petkov said, given that its simple to unhash it with a rainbow table—a lookup table used to untangle plaintext passwords from password hashes. Here are some from the Shmoo Group, for example.

Facebook in August exposed part of its source code to users. Click here to read more.

Petkov isnt posting proof-of-concept code, given that doing so would expose his server to attack. But he did outline the six steps involved in the exploit, which leverages a vulnerability in either Internet Explorer 6 or 7. Like many other exploits, his Second Life exploit retrieves valuable information returned in error logs—in this case, a victims credentials, contained in a php error log.

"It is that simple," he said. "It is automatic, and the user doesnt have to do anything (no user interaction is required)."

Its debatable whether the fault lies with Second Life or with IE. "[Second Life] can blame IE for not sanitizing. IE can blame [Second Life] for respecting autologin from a custom handler," said a poster named Ethan Malasky, in response to Petkovs initial post.

Although some responders on his blog reported that Firefox is vulnerable as well, Petkov told eWEEK that he doesnt think its possible to execute the exploit with Firefox, "unless you are running a couple of weeks old version or you know something that we dont know."

Petkov recommends that Second Life members protect themselves by unticking the "Remember password" check box within their client log-in interface. Also, he said, stop using IE. "Switch to Firefox," he said.

Linden Research, the company behind Second Life, on Sept. 19 wrote in a post that theyre working on a client-side fix to the URL-handling flaw. The company said it hopes to deploy the new 1.18.2.1 client, which will be a mandatory upgrade, this week. In the meantime, Linden is submitting a patch to the sldev mailing list, "in the hopes that the open-source developers can assist in making sure this unusually short turnaround from development to release is of high quality."

Linden is advising Second Life members to avoid hitting on unknown sites with IE, to refrain from clicking on "Second Life://" URLs on pages with IE or IE-based browsers and to change passwords immediately if Second Life starts without user intervention.

Editors Note: This story was updated to include information and comments from Linden Research.

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