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Comments considered harmful: WordPress web hijack bug revealed

A frustrated Finnish security researcher has gone public with a vulnerability in WordPress that lets attackers hijack website admin accounts.

The flaw was found by Jouko Pynnönen, and is a cross-site scripting (XSS) bug similar to one patched last week. It is buried within the widely used web publishing software's comments system.

The vulnerability is present in WordPress version 4.2 and below. Pynnönen revealed the flaw on his blog on Sunday before the WordPress team could release a patch for the software: the researcher feared WordPress would take too long to fix the hole, and wanted to warn everyone beforehand.

"I didn't report the bug to the vendor this time," Pynnönen told The Register in an email earlier today.

The security blunder is exploited by posting a 64KB comment to a WordPress blog page. This data is truncated as it is written to the database, breaking safety checks that are supposed to filter out malicious code when the comment is displayed to visitors.

This means an attacker to post a comment containing JavaScript that runs in the visitor's browser. If this comment is viewed by a site administrator reading the comments, the script will execute and can change the admin's password, create new admin accounts, deface the site, upload dodgy material, and so on. The code can hijack the accounts of normal users visiting the page, too. More...

04-29-2015 07:03