Microsoft Patches Five Critical Flaws
Security experts said two remote code execution vulnerabilities in the Windows Server Service, described by Microsoft in Bulletin MS06-035, were the most serious of those addressed Tuesday.
According to a post on the SAN Internet Storm Center web site, a heap overflow flow that exists in Mailslot is the most dangerous because it can be used to remotely attack the Windows Server Service, making it ideal for exploits such as worms that require no user interaction.
Symantec, in an advisory to subscribers of its DeepSight Threat Management System, gave the threat its highest severity rating -- 10 out of 10 -- and warned that hackers may spoof their source address to get around firewalls or disguise attack origins.
Bulletin MS06-036 addresses a remote code execution vulnerability in the way Windows handles Dynamic Host Configuration Protocol (DHCP), which is used to administer network addresses. The flaw exists because Windows DHCP client fails to check the size of user-supplied data before copying it to the memory buffer, and could be exploited by attackers to gain complete control over an infected PC.
Symantec rated the threat 9.6 in terms of severity and warned that hackers may spoof their source address to get around firewalls or disguise attack origins.
A slew of public, private and newly discovered remote code execution vulnerabilities in Microsoft Excel were targeted in Bulletin MS06-037, including flaws that Microsoft in mid-June said were being actively exploited in zero day attacks against unspecified targets.
Bulletin MS06-038 addresses remote code execution vulnerabilities in the parsing mechanism of Office applications that could pave the way for attacks using Office files with embedded malicious code. MS06-039 deals with flaws in Office that could allow .gif and .png images to be used to execute remote code.