Fake Mail Server Report Message Carries Worm

Mail server report message claims that emails containing worms have been sent from the recipient’s computer

False – Message itself carries a worm.
June 2007 – An “urgent” and somewhat redundant, warning email about this threat is circulating widely (details in commentary below).

Re: Mail server report.

Our firewall determined the e-mails containing worm copies are being sent from your computer.

Nowadays it happens from many computers, because this is a new virus type (Network Worms).

Using the new bug in the Windows, these viruses infect the computer unnoticeably. After the penetrating into the computer the virus harvests all the e-mail addresses and sends the copies of itself to these e-mail addresses

Please install updates for worm elimination and your computer restoring.

Best regards,
Customers support service

Attachment: Update-KB2703-x86

Detailed Analysis:
In late 2006, messages purports to be a “Mail server report” began hitting inboxes. The email messages attempted to trick recipients into opening an attachment by claiming that “e-mails containing worm copies” had been sent from his or her computer. The messages instructed the recipient to install updates to remove the worm infection. The update was supposedly included in an attachment that came with the email.

However, the “update” actually carried a variant of the W32.Stration worm. This family of worms is also known as Warezov. Once executed, the worm was able to download and execute remote files, harvest email addresses from the infected computer, and send itself to these addresses. Ironically, the warning about worms contained in the message more or less described the behaviour of its own malicious payload. The messages used spoofing to disguise their true origin.

Service providers and anti-virus companies would never send software updates via unsolicited email attachments. The bogus update ruse has been used before to distribute computer worms. In 2005, official looking emails that claimed to be from Microsoft carried worms disguised as “security patches”. Any message that claims the recipient needs to open an attachment to install an update should be treated with extreme caution.

The “Mail Server report” message was only one of several that carried the worm. The messages had a number of different email subject lines and various attachment names. The particular variant of this worm discussed above was being distributed late in 2006. However, the same trick was used again early in 2007 to distribute later variants of the worm. According to an April 2007 posting on the F-Secure blog, hackers were once again using the fake Mail Server Report emails to distribute malware. This later distribution did not appear to be as prolonged and widespread as the earlier 2006 attack.

During May and June 2007 an “urgent” warning email about the “Mail server report” messages began hitting inboxes. Hackers and scammers often revive the same tactics they have successfully used in the past so the warning email does retain some validity.

That said, at the time of writing, I have seen no reports that indicate that this threat is currently being widely distributed, so the warning message is somewhat redundant and tends to exaggerate the urgency of the threat. In fact, there are a number of other worms and trojans being distributed that are currently more significant threats than this “Mail Server Report” malware.

Unfortunately this tends to be a problem with email virus warnings in general. Often, the warning emails continue to circulate long after the described threat has ceased to be significant. They also have a tendency to exaggerate the amount of damage caused by the threat and often contain inaccurate and misleading information.

The best defence against email worms and other malware is to run reliable and up-to-date antivirus and anti-spyware programs, use a firewall, keep your operating system and software updated, and use caution when dealing with email attachments and links in email.

An example of the warning email:

Subject: Fwd: Heads Up…. Bad Virus – not a hoax

This is real as I read about it in Net Guide

I received an email “Mail Server Report” twice in my email box this morning, but deleted it without opening


Warn everyone you know through e-mail not to open an e-mail with “Mail Server Report” in the subject line. This one is real!

Urgent!! This is a Bad Virus Please don’t open!

This one checks out and is a bona fide real virus so hence the warning.

Any email with “Mail Server Report” in the subject line is a new virus And should not be opened. It comes with an attachment in ‘zip format’

Apparently there is a Zip file attached so be very wary of anything with a zip file on it.

The message tells you that a worm was detected in an e-mail that you Sent out and asks you to open and install the attachment to fix the Problem.

Only, it IS the problem!


Delete the e-mail. This is a real threat.

Last updated: 14th April 2007
First published: 5th October 2006
By Brett M. Christensen
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