On Tuesday, April 12, Microsoft issued information on eight new security updates. Symantec Security Response has
identified the following five vulnerabilities as the most serious:
1. Microsoft Vulnerabilities in TCP/IP - Microsoft Security Bulletin MS05 019 - This is a remote code execution and
denial of service vulnerability that occurs when an affected Microsoft platform receives and processes a malformed
TCP/IP packet. This vulnerability impacts users on Windows 2000 and Windows XP prior to Service Pack 2. Symantec
Security Response has identified this vulnerability as critical.
2. Microsoft Cumulative Security Update for Internet Explorer - Microsoft Security Bulletin MS05 020 - There are several
vulnerabilities in Microsoft Internet Explorer that could allow an attacker to take control of an affected system.
Symantec Security Response has identified this vulnerability as critical.
3. Microsoft Exchange Server SMTP Extended Verb Buffer Overflow Vulnerability - Microsoft Security Bulletin MS05 021 -
This is a vulnerability that impacts Microsoft Exchange Server 2000/2003 and could allow remote code execution. This
vulnerability is triggered by malformed SMTP extended verb commands and largely impacts enterprise users. Symantec
Security Response has identified this vulnerability as critical.
4. MSN Messenger Vulnerability - Microsoft Security Bulletin MS05 022 - This is a buffer overflow vulnerability in the
processing of malformed GIF images and could allow for malicious code execution. This issue impacts consumers using MSN
Messenger 6.2. In order for this vulnerability to be exploited, the attacker must be included on the victim's contact
list and the victim must also accept a GIF file transfer from the attacker. Symantec Security Response has identified
this vulnerability as critical.
5. Microsoft Word Vulnerabilities - Microsoft Security Bulletin MS05 023 -There are two vulnerabilities in Microsoft
Word that could allow an attacker to run arbitrary code on a user's system. If a user is logged on with administrative
privileges, an attacker who successfully exploited this vulnerability could take complete control of an affected system,
including installing programs, viewing, changing, or deleting data, or creating new accounts with full privileges.
Symantec Security Response has identified this vulnerability as critical.
"It is important that both home users and enterprises take proactive steps to deploy these patches," said Oliver
Friedrichs, senior manager, Symantec Security Response. "The vulnerabilities announced by Microsoft today can result in
broad exposure to blended threats and worms, as well as denial of service attacks. The combination of a strong patch
management strategy and keeping strict best practices is the best way to avoid being impacted by any malicious threat."
Symantec Security Response had raised the ThreatCon from a Level 1 to a Level 2.
Symantec recommends the following actions for enterprises:
• Evaluate the possible impact of these vulnerabilities to their critical systems.
• Plan for required responses including patch deployment and implementation of security best practices using the
appropriate security solutions.
• Take proactive steps to protect the integrity of networks and information.
• System managers should verify that appropriate data backup processes and safeguards are in place and effective as a
best practice.
• Exercise caution in opening all unknown or unexpected attachments to e-mail, and in following Web links from unknown
or unverified sources.
Symantec recommends the following actions for home users:
• Regularly run Windows Update and install the latest security updates to keep software up to date.
• Be aware that opening unknown or unexpected attachments to e-mail or following Web links from unknown or unverified
sources is not advised.
• For more comprehensive security protection, consider using an Internet security solution such as Norton Internet
Security to protect against today's known and tomorrow's unknown threats.
Symantec will closely monitor further information related to these vulnerabilities, and will provide updates and
security content as necessary. Information on Microsoft's April 2005 Security Bulletin can be found athttp://www.microsoft.com/technet/security/bulletin/ms05-apr.mspx.