Microsoft Windows contains a vulnerability when handling embedded OpenType fonts that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability is due to improper sanitization of user-supplied input in embedded OpenType fonts. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious document. If the user views the document, the attacker could execute arbitrary code with the privileges of the user.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.
Indicators of Compromise
The following Microsoft systems are affected:
Windows 2000 SP4 and prior
Windows XP SP3 and prior
Windows XP Professional x64 Edition SP2 and prior
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Server 2003 for Itanium-based Systems SP2 and prior
Windows Vista SP2 and prior
Windows Vista x64 Edition SP2 and prior
Windows Server 2008 for 32-bit Systems SP2 and prior
Windows Server 2008 for x64-based Systems SP2 and prior
Windows Server 2008 for Itanium-based Systems SP2 and prior
Windows 7 for 32-bit Systems
Windows 7 for x64-based Systems
Windows Server 2008 R2 for x64-based Systems
Windows Server 2008 R2 for Itanium-based Systems
The vulnerability is due to improper sanitization of user-supplied input in embedded OpenType fonts. The processing of a document that contains a malicious font could trigger an integer overflow, leading to a heap overflow during memory operations. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious document, which may be a website or text document. When viewed, the document could trigger memory corruption that the attacker could use to execute arbitrary code with the privileges of the user.
Attackers cannot directly exploit this vulnerability and instead must rely on user interaction to accomplish an exploit. The attacker must convince the user to view a document that contains a malicious embedded OpenType font. Attackers may provide documents as attachments to e-mail messages or provide links to users in e-mail messages or posted on public websites.
If the user views the malicious document, the attacker could execute arbitrary code with the privileges of the user. Systems that grant users Administrator privileges may be impacted the most because any code execution would occur with full privileges, possibly resulting in a complete system compromise. However, systems on which users run applications with restricted privileges are likely to be at less risk because any executed code would run in a limited security context.
Administrators are advised to apply the appropriate updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Users are advised to run applications with the least necessary privileges.
Administrators may consider disabling support for parsing embedded fonts in Internet Explorer.
Administrators may consider restricting access to the t2embed.dll library to prevent embedded font rendering.
Administrators are advised to monitor critical systems.
Microsoft has released a security bulletin at the following link: MS10-001
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
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