Patch Tuesday: Malicious fonts bedevil Microsoft Windows

Microsoft fixes multiple vulnerabilities in how the company's software renders TrueType fonts

Of the six critical security bulletins Microsoft issued in its Patch Tuesday monthly release of software updates, three address a vulnerability in how Microsoft software renders fonts.

"Fonts have become really complicated," said Wolfgang Kandek, chief technology officer for compliance and security software company Qualys. "There is real processing going on when you print a character, and that complexity can be attacked."

The number of critical bulletins Microsoft released this month is a bit higher than normal, Kandek said. Typically, Microsoft will issue about two or three critical bulletins on Patch Tuesday, which occurs on the second Tuesday of each month. This month half the bulletins -- MS13-052, MS13-053 and MS13-054 -- address how Microsoft systems handle the rendering of TrueType fonts.

With this vulnerability, an attacker can embed malicious values in a font description that would overrun the memory allocated to the font-drawing routine, and write into sections of memory reserved for other operations. The font instructions could be provided to Windows or Internet Explorer (IE) by way of a Web page or a document.

"Depending on where this happens, this can be quite serious," Kandek said.

Windows, for instance, renders all characters onto the screen as a system user, not as a standard user, which has fewer system privileges. An exploit of a font-rendering vulnerability could "go right into the operating system and take control at that level," Kandek said.

Overall, Microsoft issued six critical bulletins, covering Windows OS, the .NET Framework, Silverlight, Office, Visual Studio, Lync and IE. A seventh bulletin, labeled as important, covers the Windows Defender security software.

All six of the critical bulletins include remote code execution vulnerabilities, which can be used to provide attackers with illicit access to machines.

Seventeen of the 34 vulnerabilities covered in the bulletins address IE. "Researchers continue to find flaws in IE, and the attack surface is pretty big," Kandek said, referring to how Microsoft is now supporting five different versions of the browser. The vulnerabilities affect IE versions six through 10 that run on Windows XP, Windows Vista, Windows 7, Windows 8, Windows Server 2003, Windows Server 2008 and Windows RT.

"The major problem there is that users or companies still maintain old versions of the browser. We would be better off if everyone was on the newer version" of IE, Kandek said.

One Windows vulnerability, which affects memory management, has already been publicly revealed, and has been used for an exploit that can run on the Metasploit penetration testing software. Security researchers are urging administrators to update their own versions of Windows XP, Windows Vista, Windows 7, Windows 8 and Windows 2008, Windows 2012 and Windows RT as soon as possible.

"July is one of the uglier releases we've seen from Microsoft this year. To say that all Microsoft products are affected and everything is affected critically is not an overstatement," wrote Lumension security and forensic analyst Paul Henry in an email statement. "It's difficult to prioritize one or two because all the bulletins likely need your attention this Patch Tuesday."

In addition to Microsoft patches, administrators should also take a look at Adobe's monthly set of patches, also released Tuesday. They cover vulnerabilities in Adobe Flash, Shockwave and ColdFusion, which is server-side software for rendering websites.

Joab Jackson covers enterprise software and general technology breaking news for The IDG News Service. Follow Joab on Twitter at @Joab_Jackson. Joab's e-mail address is Joab_Jackson@idg.com

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.

Tags Microsoftpatch managementmalwarepatchesExploits / vulnerabilities

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Joab Jackson

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

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?