Microsoft patches 23 Windows flaws, warns of risk of code execution attacks

Microsoft wheeled out another batch of  security patches today to fix multiple dangerous security flaws that expose billions of Windows users to remote code execution attacks.

The Patch Tuesday batch for May 2012 covers at least 23 documented vulnerabilities in Microsoft Office, Microsoft Windows, the Microsoft .NET Framework and Microsoft Silverlight.

The company is urging Windows users to pay special attention to MS12-034, a "critical" bulletin that patches 10 distinct security holes.  Three of these vulnerabilities have already been publicly disclosed and Microsoft expects to see working exploit code released within 30 days.

The vulnerable code in the MS12-034 bulletin is linked to the Duqu malware that was used to spy on high-profile targets in Iran.

Some details:

• MS12-034 (Microsoft Office, Windows, .NET Framework, and Silverlight): This security update resolves three publicly disclosed vulnerabilities and seven privately reported vulnerabilities in Microsoft Office, Microsoft Windows, the Microsoft .NET Framework, and Microsoft Silverlight. The most severe of these vulnerabilities could allow remote code execution if a user opens a specially crafted document or visits a malicious webpage that embeds TrueType font files. An attacker would have no way to force users to visit a malicious website. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes them to the attacker's website.

Microsoft is also highlighting MS12-029 as another high-priority update that should be deployed immediately.   This bulletin, also rated critical, addresses a security flaw in Microsoft Word that could be exploited by hackers to take complete control of a vulnerable machine. Attack vectors for this issue include maliciously crafted websites and email, the company said.

Here's a glimpse at the rest of this month's updates:

• MS12-035: This security update resolves two privately reported vulnerabilities in the .NET Framework. The vulnerabilities could allow remote code execution on a client system if a user views a specially crafted webpage using a web browser that can run XAML Browser Applications (XBAPs). Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
• MS12-030: This security update resolves one publicly disclosed and five privately reported vulnerabilities in Microsoft Office. The vulnerabilities could allow remote code execution if a user opens a specially crafted Office file. An attacker who successfully exploited these vulnerabilities could gain the same user rights as the logged-on user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
• MS12-031: This security update resolves a privately reported vulnerability in Microsoft Office. The vulnerability could allow remote code execution if a user opens a specially crafted Visio file. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
• MS12-032: This security update resolves one privately reported and one publicly disclosed vulnerability in Microsoft Windows. The more severe of these vulnerabilities could allow elevation of privilege if an attacker logs on to a system and runs a specially crafted application.
• MS12-033: This security update resolves a privately reported vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker logs on to a system and runs a specially crafted application. An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.