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Viruses transmitted via emails are very common and cannot be avoided by using only antivirus software. Some additional checks need to be carried out to protect email vulnerabilities.
Love Letter is the most harmful type of viruses transmitted in email and causes great loss within minutes in the email systems and corporate networks. Some viruses are sent via attachments while some are sent using the messages within the emails that run automatically. “Nimda” is an example of such virus that runs automatically i.e. don’t require intention of the user.
An email containing infected attachments entails with malformed MIME headers, and HTML mails with embedded scripts should be found in the emails to protect email system from current and future viruses. There are various tests that should be conducted in order to secure email system from the email vulnerabilities. Some of them are as under:
· Long subject attachment checking bypass test
Checks whether system accepts emails with long subjects.
· Attachment with no filename vulnerability test
Examines whether system accepts an attachment with no filename containing executable code that can bypass content checking security solutions.
· Long filename vulnerability test
Indicates whether system blocks emails with attachments having long filenames, which can be used to trick a user into double-clicking the attachment, which can execute the malicious code it contains on the system.
· Popup Object Exploit vulnerability test
Discover if machine is vulnerable to the Popup Object Exploit which can automatically launch files on a vulnerable system.
· Double file extension vulnerability test
Shows whether email system accepts emails which contain attachments with double file extensions.
· ActiveX vulnerability test
Finds out if machine is vulnerable to the ActiveX exploit.
· CLSID extension vulnerability test
Reveals whether mail server detects and blocks files with Class ID (CLSID) extensions.
· CLSID extension vulnerability test
Reveals whether Outlook 2002 (XP) system detects and blocks files with Class ID (CLSID) extensions.
· Eicar anti-virus software test
Check if anti-virus software is in place and functioning correctly.
· Fragmented message vulnerability test
Checks whether server-level anti-virus/content checking system detects and blocks emails using the fragmented message exploit.
· GFI's Access exploit vulnerability test
Discover if machine is vulnerable to the Access exploit vulnerability discovered by GFI. It does not apply to IE6 users who have the latest patches installed.
· Iframe remote vulnerability test
Discover if machine is vulnerable to the Iframe remote exploit. It does not apply to IE6 users who have the latest patches installed.
· Malformed file extension vulnerability test
Examines whether Outlook 2002 (XP) system detects and blocks files with malformed HTA file extensions.
· MIME header vulnerability test (Nimda & Klez testing)
Examines whether system is protected against emails using the MIME exploit. It does not apply to IE6 users who have the latest patches installed.
· Object Codebase vulnerability test
Examines whether system detects and blocks emails using the Object Codebase exploit. It is also suited to Outlook 2002. It does not apply to IE6 users who have the latest patches installed
· VBS attachment vulnerability test
Checks whether mail server blocks VBS attachments.
If you are alarmed by these vulnerabilities, there exist solutions. Look out for companies ask for name and email address to sign up in order to check email system against all these vulnerabilities. On signup an email is send containing the link for confirmation. After the confirmation the email testing is performed on the system and results are send back in email.
