Yahoo Instant Messenger contains security flaw

Security researchers are warning of a security hole in Yahoo's Messenger that could allow attackers to run their own code on computers using the instant messaging program.

The buffer overrun vulnerability was discovered by researcher Tri Huynh in a file named "yauto.dll," which is an ActiveX component of Messenger software versions up to 5.6.0.1347, according to a security alert released Wednesday by Secunia Ltd. of Copenhagen, Denmark.

The company was notified via e-mail about the hole one month ago, but did not respond, Secunia said.

Yahoo issued a statement Wednesday saying that the company only learned of the vulnerability Tuesday evening, after it was posted on public Internet bulletin boards, and is working to verify the report and develop a patch for Messenger, Yahoo said.

"Yahoo! takes security very seriously and employs rigorous and aggressive measures to help protect our users," the statement said.

Messenger allows users to instantaneously communicate with each other over the Internet using text messages. It also lets users send files or links to Web pages. Instant messaging applications such as Yahoo!'s Messenger, Microsoft Corp.'s MSN Messenger and America Online Inc.'s AOL Instant Messenger are increasingly used at companies to let workers communicate with each other over corporate LANs.

ActiveX is a Microsoft technology that allows software developers to create small, reusable bits of code, called "controls" that enable programs to share information over computer networks and the Internet.

Attackers could trigger a buffer overrun on machines running Messenger by sending a long stream of data in the form of a Web page URL (uniform resource locator) to a vulnerable function within yauto.dll, crashing the application or allowing the attacker to place his or her own malicious code on the machine, according to Secunia.

To launch an attack, hackers could set up a Web page, then lure Messenger users into visiting the site and clicking on a link that triggers the buffer overrun and runs the attack code, Secunia said.

In buffer overflow attacks, hackers use flaws in a software program's underlying code to overwrite areas of the computer's memory, replacing legitimate computer instructions with bad data or other instructions.

Secunia rated the Messenger vulnerability "highly critical," saying that researchers tested the hole and successfully exploited it by downloading and running a Trojan horse program.

Messenger users running vulnerable versions of the program were advised to remove yauto.dll from their computer hard drive. Users should also consider modifying their Web browser configuration to prevent ActiveX controls and Active Scripting from running, except on approved Web sites, Secunia said.

Yahoo said it encourages security community members to adhere to industry practice and contact the company directly using the e-mail address security@yahoo-inc.com. The security hole in yauto.dll was not reported using this address, Yahoo said.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Paul Roberts

IDG News Service
Show Comments

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Tom Pope

Dynabook Portégé X30L-G

Ultimately this laptop has achieved everything I would hope for in a laptop for work, while fitting that into a form factor and weight that is remarkable.

Tom Sellers

MSI P65

This smart laptop was enjoyable to use and great to work on – creating content was super simple.

Lolita Wang

MSI GT76

It really doesn’t get more “gaming laptop” than this.

Jack Jeffries

MSI GS75

As the Maserati or BMW of laptops, it would fit perfectly in the hands of a professional needing firepower under the hood, sophistication and class on the surface, and gaming prowess (sports mode if you will) in between.

Taylor Carr

MSI PS63

The MSI PS63 is an amazing laptop and I would definitely consider buying one in the future.

Christopher Low

Brother RJ-4230B

This small mobile printer is exactly what I need for invoicing and other jobs such as sending fellow tradesman details or step-by-step instructions that I can easily print off from my phone or the Web.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?