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Comment Reg Developer recently published a story about listings on eBay that point users to phishing sites. We thought we'd uncovered a new security issue on eBay, but it turns out we were wrong.

Not wrong about the security issue, there certainly is one. Our error was in assuming that it was new and/or that eBay didn't know about it.

Starting from some leads provided by you lot, we have found out that this issue has been well-documented for at least a year.

For example, it is described in a US-CERT vulnerability note dated 02/05/2006, which says: "eBay is a popular auction website. When an eBay user posts an auction, eBay allows SCRIPT tags to be included in the auction description. This creates a cross-site scripting vulnerability in the eBay website."

So the root of the problem is that users are allowed to post active code and active code can be used for malicious purposes.

What can eBay do? Well, if it chose to, it could restrict the HTML that users post to its site. This could have two effects, depending on what restrictions the company enforced: 1) it could ensure that the listing was rendered perfectly safe for other users, or 2) it could restrict the dynamic content that some perfectly legitimate users like to post.

So eBay has to strike a balance between security for its users and the functionality it offers them.

Over a year ago eBay apparently made a conscious decision not to restrict the HTML in this way. In an interview in March 2006, an eBay spokeswoman, Catherine England, is quoted as saying:

"Our sellers really use the dynamic content aspect of our listings. The benefits overwhelmingly outweigh the red skin that we have gotten.

"By the time something gets up there, we're usually so quick to get it and pull it down that it is really a moot point. We feel that it is not a huge concern or issue - it is miniscule."

As we found two weeks ago, "quick" can equate to more than two hours. There is evidence on eBay's own Trust and Safety community board, (here and here), that a malicious listing can stay up for considerably longer than two hours.

These are well worth reading (thanks to Reg Dev reader Lee Berkovits for them). A week may be a long time in politics. On the web even two hours is more than enough time for multiple listings to phish multiple identities.

Do a few identity thefts really matter? They don't seem too bad if you believe that most phishers are school kids in bedrooms trying to steal an eBay identity so they can buy a bigger Wii than their mate's. Sadly, as The Register has shown (here and here), all too often organised crime is behind modern phishing expeditions.

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