An update to Kaspersky Labs' enterprise anti-virus software inadvertently slowed Windows servers to a crawl, the Russian net security firm has admitted.

Kaspersky has pulled the misfiring update and promised a review of its testing procedures to determine why the potential problem was not spotted prior to the release of the software. The snafu - which provoked howls of anguish from sysadmins on Kaspersky's forums - comes only days after an insecure third-party application meant that that portions of Kaspersky's US website became conduits for malware distribution and caps a truly awful week for the security software outfit.

In a statement, Kaspersky apologised for the inconvenience created by the misfiring update to its Anti-Virus 6.0 for Windows Servers Enterprise Edition security software.

Kaspersky Lab confirms that Kaspersky Anti-Virus 6.0 for Windows Servers Enterprise Edition caused CPU overload on Windows Server operating systems At 14:52 (MSD) on 23 October 2010, an incorrect database update was released for Kaspersky Anti-Virus 6.0 for Windows Servers Enterprise Edition. No problems were detected during testing of the update. The problem arose from an error in the testing procedure which was not immediately spotted due to the complexity of the script used to test for excessive CPU usage.

Only users of the enterprise server security software and not users of the Russian firm's PC client security packages were affected by the glitch, which left machines spinning through a continuous loop of misery as the program loaded up and crashed every few minutes. The problem arose when the release was published on Saturday and was only fixed on Monday.

The only product affected by the update was Kaspersky Anti-Virus 6.0 for Windows Servers Enterprise Edition 6.0.2.555. This resulted in the security solution overloading the CPU on Windows Server operating systems, which was caused by the kavfswp.exe service restarting in an infinite loop at intervals of 2-5 minutes. As soon as the error was reported to Kaspersky Lab, the company's experts investigated the root cause, implemented the required changes to the antivirus databases and performed tests using a variety of scenarios. At 14:46 (MSD) on 25 October, a database update was released that resolved the problem.

The Russian firm said that additional checks for CPU overloads will be added to Kaspersky Lab's testing procedures in order to safeguard against a repeat of the problem in future. ®