The SirCam worm has revealed weaknesses in anti-virus protection relied on by many firms as a first line of defence against viral infection.
It's been discovered that both Baltimore Technologies MIMEsweeper content filtering software and Symantec's perimeter protection product, Norton Antivirus for Gateways v2.x, fail to block the prolific virus.
Norton Antivirus for Gateways fails to see email with attachments contaminated by the virus, even if the correct settings have been applied and the latest versions of virus-identfying signature files have been downloaded.
Eric Chien, chief researcher at Symantec's antivirus research centre, admitted the problem, which has generated a considerable number of frustrated messages to Symantec's support site, arises because of a know flaw with its products.
When SirCam spreads itself by email the messages generated have an invalid or mangled MIME-header, because of which Symantec's products don't recognise that an email has an attachment.
The same bug in Symantec's desktop software means Norton Antivirus also fails to detect SirCam with its POP email filter.
Chien admitted the issue meant Symantec's email auto protection is ineffective at blocking the prolific worm but stressed that Norton Antivirus would detect SirCam if a users tried to either open or save an infected attachment to disk.
Symantec is developing a patch for its products, which is currently in testing, and will be made available to users as a component of LiveUpdate, a feature of Symantec's products which allows users to update virus definition files.
The way SirCam is constructed, which if you've received copies of the worm would seem easy to recognise, is also tripping up Baltimore Technologies content filtering program, MAILsweeeper.
MAILsweeeper fails to recognise that an email infected with SirCam has an attachment (again because of the malformed MIME header). This which means that users who configure the software to deliver emails of an undetermined nature, rather than putting such messages into quarantine, will see copies of SirCam arriving at their desktop email clients.
As previously reported, SirCam spreads itself as an attachment to email messages (or possibly network shares), and may in certain cases delete files from a victim's hard disk.
SirCam snaffles up files from a user's hard disk and wraps them in viral code before propagating itself to email addresses filched from a victim's address book or temporary Internet cache files.
The subject of an infected email will be the name of the attached file, and users can spot infected attachments because they feature a double extension, such as .doc.pif. The text of emails may start "Hi! How are you?" and end "See you later. Thanks", or the Spanish equivalents, but variations on this are possible.
MessageLabs, a managed services firm which scans its users email for viruses, has 45,850 copies of SirCam, which suggests the virus is up there with the Love Bug and slower burning Hybris worm as the worst virus in history.
At the risk of stating the bleeding obvious it's worth repeating, yet again, that users are advised to delete any suspicious emails without opening them and to update their antiviral protection. ®
Write up on SirCam by Symantec
MessageLabs stats on SirCam
Baltimore Technolgies' advice on MAILsweeper and SirCam
Symantec's support forum on Norton Antivirus for Gateways Lots of confused users, why can't Symantec let them know what's going on properly?
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