Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability is due to improper handling of Unicode character sequences.† An unauthenticated, remote attacker could exploit this vulnerability by sending malicious requests to a vulnerable service or by convincing a targeted user to view a malicious document.† If successful, the attacker could cause the targeted application to fail, resulting in a DoS condition.
Microsoft confirmed the vulnerability in a security bulletin and released updated software.
Indicators of Compromise
The following Microsoft systems are affected:
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 SP1 and prior
Windows 7 for x64-based Systems SP1 and prior
Windows Server 2008 R2 for x64-based Systems SP1 and prior
Windows Server 2008 R2 for Itanium-based Systems SP1 and prior
The vulnerability is due to improper handling of Unicode character sequences by the Microsoft DirectWrite API.
An unauthenticated, remote attacker could exploit the vulnerability by convincing a user to view a malicious document that contains Unicode characters or by sending requests to network services that accept Unicode.† The processing of the Unicode character sequences could cause an error condition that could cause the application or service to terminate, resulting in a DoS condition.
Only network-aware applications that accept and process Unicode, such as instant messaging clients, are vulnerable to remote exploitation.† Systems without exposed applications may have no vector for remote exploitation and instead require user interaction to accomplish an exploit.
Administrators are advised to apply the appropriate updates.
Administrators may consider periodically clearing the DNS Server cache.
Administrators are advised to monitor affected systems.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Microsoft has released a security bulletin at the following link: MS12-019†
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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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.