Some e-mail worms, like the widespread Bagle-family, uses password-protected files in an attempt to fool antivirus scanners. F-Secure Anti-Virus provides methods that can be used to detect the presence of suspicious files inside encrypted archive files. These methods provide generic detection and work for all present and future worms that uses a similar technique.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
These features are disabled by default due to the fact that they may have a negative impact on the scanning performance or block some legitimate attachments in mail traffic. This article describes how a user can enable these features and ensure that worms can't replicate using password-protected archives.
More information can be found from our Support pages: