Update: Sasser worm could hit hard today
Experts warned it could spread quickly today as workers returned to the office with infected laptops
Computerworld - Microsoft Corp. issued an unusual weekend security warning Saturday that a worm has been unleashed on the Internet taking advantage of a security hole announced publicly last month (see story). Microsoft once again urged users to install its most recent critical Windows updates.
The worm's impact is expected to peak today as millions of workers bring their laptops back to their offices after using them over the weekend to access the Internet from relatively unsecured home locations.
Microsoft rated the vulnerability exploited by the W32/Sasser A and Sasser B worms as critical, and security experts urged all users of vulnerable system to apply patches immediately.
"Microsoft has verified that the worm exploits the Local Security Authority Subsystem Service (LSASS) issue addressed in Microsoft Security Update MS04-011 on April 13, 2004," the company said in an announcement posted yesterday and updated yesterday morning. In its security update, Microsoft included a tool that checks for system infection by the Sasser worm.
Versions of Windows XP and 2000 are vulnerable, although not XP 64-Bit Edition Version 2003, Microsoft said.
The worm has positioned itself as one of the quickest-spreading and most virulent ones around, suggesting that the number of incidents will soar at the beginning of the week, according to Luis Corrons, director of security vendor Panda Software SL's PandaLabs unit.
The Sasser worm works in a similar way to last year's Blaster worm, but has not yet spread so quickly, according to Graham Cluley, senior technology consultant at security vendor Sophos PLC.
Despite the Microsoft warning, some users may be reluctant to apply the needed patches, however, since there have been reports that the fixes create new system problems, such as causing some systems to slow down or stop responding (see story).
Both Symantec Corp. and Network Associates Inc.'s McAfee antivirus unit rated Sasser as medium risk, while Computer Associates International Inc. rated it low risk. Trend Micro Inc. said it issued a yellow alert to its customers.
Later yesterday, Symantec upgraded the Sasser threat to 4 on its scale of 1 (very low) to 5 (very severe) because of the rising number of infections.
Sasser spreads by scanning IP addresses for access via TCP Port 445 looking for vulnerable systems, according to Symantec. When it finds an unpatched Windows XP or Windows 2000 computer, Sasser.A adds the file "avserve2.exe"="%Windir%\avserve2.exe" in the registry, tries to block attempts to shut down or reboot the infected computer (by using the AbortSystemShutdown application programming interface) and then begins scanning other systems via an FTP server on TCP Port 5554 seeking to spread itself, Symantec said.
- Fight Malware, Malfeasance and Malingering Every year brings more extreme sets of threats than the last. The good news is that there are a range of mitigation options....
- Comprehensive Advanced Threat Defense The hot topic in the information security industry these days is "Advanced Threat Defense" (ATD). This paper describes a comprehensive, network-based approach to...
- Advanced Threat Defense: A Comprehensive Approach In this interview, Peter George, president, General Dynamics Fidelis Cybersecurity Solutions, explains why we need more than anti-malware, and what constitutes a comprehensive...
- Who's Spying on You? You're aware of the threats of malware to your business but what about the ever-changing ground rules? Cybercriminals today are launching attacks against...
- NSS Labs & Cisco Present: Evaluating Leading Breach Detection Systems Today's constantly evolving advanced malware and APTs can evade point-in-time defenses to penetrate networks. Security professionals must evolve their strategy in lockstep to...
- Will the Real Endpoint Threat Detection and Response Please Stand Up? This webinar explores new technologies & process for protecting endpoints from advanced attackers as well as the innovations that are pushing the envelope... All Malware and Vulnerabilities White Papers | Webcasts