It's surprising it's taken this long, but the Pentagon, fearing security problems, has reportedly banned flash drives from being used in the building. Numerous outlets are confirming the story, noting that all removable media is being banned.

USB flash drives are becoming increasingly common as an entry point for viruses to attack PCs. Now that floppy disks and even optical media have largely fallen out of favor, it's thumbdrives that are picking up the slack. The devices can be particularly dangerous since there's no built-in security mechanism to protect against infections on them: Even if a PC has no antivirus software installed, chances are the computer's web browser will offer some rudimentary protection against malicious websites. Webmail is also now commonly protected by default through anti-spam and antivirus measures. But no such protections exist for most thumbdrives.

The Pentagon, which is collecting thumbdrives from workers and has offered no promises when or if they'll be returned, noted Friday that a major (yet unnamed) "global virus" was making the rounds (potentially a Chinese-based attack), one which circulates particularly through the use of external media.

In related news, just last week Symantec noted that it was "currently observing an increase in malicious applications that use USB flash drive devices as a propagation method," noting that by the end of 2007 a whopping 40 percent of malware that was propagated did so via "shared executable files," which copy themselves to and from removable storage devices.

The best protection is to install an OS-based antivirus application and make sure it is set to scan removable media whenever a new drive or disc is inserted into the computer and turn off all auto-run/auto-play features in Windows.