Opera Patches Browser Flaws

Opera has released a new version of its Web browser, which closes two security holes that could allow someone to remotely take control of a computer. The new version, released Friday, also incorporates a patch for the OpenSSL protocol, according to developer Opera Software.

Versions 7 to 7.22 of the browser for Windows contain both security flaws: using them to visit a specially crafted Web page could allow someone to remotely take control of a computer. The same versions for Linux contain only one of the flaws, a buffer overflow vulnerability.

The company recommends upgrading to Version 7.23, according to a note on its Web site.

Bug Hunter

Finnish software developer Jouko Pynnonen informed Opera Software of the flaws on November 12, he wrote in a message to the BugTraq mailing list on Saturday. Pynnonen has previously reported security holes in Microsoft's Internet Explorer browser and Windows Media Player applications.

Code that allows users to download and automatically install new "skins" for Opera is at the root of the problems. Skins are files which allow the appearance of an application to be modified, changing the color scheme or typeface in accordance with a particular theme.

Opera is flawed in the way it checks the validity of the name and content of such files before downloading them, according to Pynnonen. A malicious Web page can be created to exploit this flaw, allowing the Web page designer to save a file in arbitrary locations on Windows machines that use Opera to visit the page. Such a file saved into the Startup directory could be crafted to take arbitrary actions with the user's privileges the next time the machine is rebooted, such as deleting files or installing a virus.

Another Flaw

The other flaw reported by Pynnonen is a buffer overflow vulnerability affecting Windows and Linux versions of the browser. If the user is tricked into downloading a malformed skin file, a buffer overflow condition can occur, theoretically allowing the execution of arbitrary code. Pynnonen has not found a way to exploit this flaw in practice, he wrote in his message to BugTraq.

In addition to closing these holes, Version 7.23 of Opera incorporates a patch for code that handles the OpenSSL protocol. The patch was released by OpenSSL's creators on Nov. 4, and addresses a bug which could cause the browser to crash if sent invalid data about a secure Web site's security certificate, according to an announcement on the OpenSSL Web site.

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