Tools Fight Forensics

A breadth of anti-forensics tools -- most of them free -- is making it easier for the bad guys to cover their tracks in malware and data theft attacks.

"The bottom line is most criminals are not the brightest bolts in the box and they tend to make mistakes, which forensics has been able to use to its advantage," says Paul Henry, vice president of technology evangelism for Secure Computing. Henry will discuss the increasingly popular anti-forensics tools at a session at InfoSec World in Orlando this week. "But a smarter individual can [today] easily find tools to cover his tracks."

Many of these tools help attackers mask or alter timestamps, which forensics investigators traditionally have used to track down and implicate attackers. "The problem today, in a nutshell, is these freely downloadable tools on the Net make it nearly impossible to use file timestamps as a true evidentiary trail," he says. "There are a few tools that let you change MAC times [timestamps] after the fact... Today you can alter MAC times so that it shows you could not have possibly been the one that perpetrated the crime."

The main types of anti-forensics tools include encryption, disk-wiping, steganography, packing, and binder techniques, Henry says, as well as bypassing known signatures, virtualization, and hiding in memory/RAM.

If an attacker encrypts his malware or evidence of an attack, "all bets are off," Henry says. TrueCrypt, for instance, can randomize data in an encrypted partition so you can't even prove that it's encrypted. It basically creates a hidden encrypted volume of data within another encrypted volume. That way, the key data is undetectable, he says.

Disk-wiping is gaining in popularity among the black hat set, and fast, Henry says. CyberScrub is one such tool, another is Wipe&Clean.

Packing programs, which let you change the signature of an execute file and cannot be detected by an antivirus scanner, are enjoying a resurgence -- within trojans and worms, Henry says. "Packers keep changing themselves so signatures don't recognize them," he says. "They are getting quite good" and difficult to detect.

Binders roll two or more executables into one executable file so the attacker can attach a keylogger or trojan with it as well, he says.

And virtualization technology is making forensics investigation even more difficult. Tools like MojoPac make your USB fob or your iPod basically become a PC around your neck, and running them leaves no timestamp trace on the host system, Henry says. "All you get on the host is a registry entry that the new USB device was inserted, or when you configure it to auto-start on insertion." But it doesn't show any trace of malicious activity that may have occurred while running Mojo, he says.

"The BartPE tool creates a bootable environment off a CD-ROM, and then it never touches the hard drive... It's only resident in RAM," he says.

That's bad news for forensics investigators. Still, if organizations deploy application-layer security, such as application proxies rather than just packet-filtering firewalls, they can capture some attack evidence that can help track attacks and attackers, he says. You need application-layer firewalls (which Secure Computing sells) that enable logging so you can capture more than the IP address and port number security, he says. "Then you can get evidence of a break-in in firewall logs, even if the perpetrator wiped off the PC he compromised."

And all is not lost for the forensics field yet, he says. But whole-disk encryption, such as that of Windows Vista, won't help. "Encryption has always been the bane of forensics."

— Kelly Jackson Higgins, Senior Editor, Dark Reading