A list of the worst 20 security vulnerabilities bedevilling Windows and *Nix systems was unveiled last Friday by the SANS (SysAdmin, Audit, Network, Security) Institute.

The list, now in its fifth year, is designed to help admins to prioritise their efforts so that they can close the most dangerous security holes first. It highlights the top 10 Windows and top 10 Unix issues in their relative order of importance. The roll of infamy is decided by a panel of IT security industry reps, academics, users organisations and the SANS Institute.

Top Vulnerabilities to Windows Systems

1. Web servers & services
2. Workstation service
3. Windows remote access services
4. Microsoft SQL Server
5. Windows authentication
6. Web browsers
7. File-sharing applications
8. Window’s Local Security Authority Subsystem Service risks
9. Mail client
10. Instant messaging

Top Vulnerabilities in Unix and Linux Systems

1. BIND Domain Name System
2. Web server
3. Authentication
4. Version control systems
5. Mail transport service
6. Simple Network Management Protocol (SNMP)
7. Open Secure Sockets Layer (SSL)
8. Misconfiguration of Enterprise Services NIS/NFS
9. Databases
10. Kernel

As with previous years the list is fairly general and will generate few surprises among security pros. Despite this the vulnerabilities it recounts are frequently ignored. These ommissions are a key factor in the spread of destructive worms. SANS line is that simple precautions, prompted by raised awareness, can save far greater problems further down the line.

In a statement SANS said: "The vast majority of worms and other successful cyber attacks are made possible by vulnerabilities in a small number of common operating system services. Attackers are opportunistic. They take the easiest and most convenient route and exploit the best-known flaws with the most effective and widely available attack tools. They count on organizations not fixing the problems, and they often attack indiscriminately, scanning the Internet for any vulnerable systems. The easy and destructive spread of worms, such as Blaster, Slammer, and Code Red, can be traced directly to exploitation of unpatched vulnerabilities."

"Although there are thousands of security incidents each year affecting these operating systems, the overwhelming majority of successful attacks target one or more of these twenty vulnerable services," it added. ®

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