USB drives pose insider threat
The latest 'Trojan horse'
In a recent test of a credit union's network security, consultants working for New York-based security audit firm Secure Network Technologies scattered 20 USB flash drives around the financial group's building.
Each memory fob held a program - disguised as an image file - that would collect passwords, user names and information about the user's system. Fifteen of the USB drives were picked up by employees, and surprisingly, all fifteen drives were subsequently plugged into credit union computers.
The test confirmed that employees play a key role in a company's security and that many workers still do not understand the danger of USB drives, said Steve Stasiukonis, vice president and founder of Secure Network Technologies.
"Most companies know that USB devices are a problem," he said. "But to them it's a potential issue. They haven't heard about a lot of people being exploited by such techniques."
Data leaks have become a major issue in the past year, as company after company suffers a laptop theft or a leak caused by poor security.
Fast-spreading internet worms have become less popular among malicious coders in favour of bot software and other attack tools designed to compromise PCs with an eye toward profits. And companies have been specifically targeted by attackers using Trojan horse programs - attached to email, CDs or USB drives - to steal valuable data.
Using removable media to steal data from a company or surreptitiously install rogue programs on corporate computers dates back to the days of magnetic tape drives and floppy disks. Yet, while a writable CD or floppy disk in a coat pocket might raise eyebrows today, USB tokens have become a common accessory, keeping company with car and house keys.
It's no surprise, then, that USB keys have become a popular way to sneak data out from companies. Almost 37 per cent of businesses surveyed by the Yankee Group in 2005 blamed USB drives for contributing to the disclosure of company information. Nearly two thirds of the leaks resulted in some disruption to the business units involved, according to the analyst firm.
Those numbers, as well as the case of the cracked credit union, come as no surprise to Vladamir Chernavsky, CEO of AdvancedForce InfoSecurity Solutions, which sells a security application, called DeviceLock, for protecting USB ports and other device connections on a computer.
"Three years ago, it took us a lot of work to convince people that USB tokens were a security threat," Chernavsky said. "Now, we don't have to struggle to convince people because everyone understands it's an issue."
After analysts flagged iPods as a potential threat, corporate security professionals looked at all removal storage with more suspicion, Chernavsky said. Yet, because USB drives are easy to use and extremely portable, they have become perhaps the most popular choice for transporting modest amounts of data. Moreover, so-called USB smart drives, which add the ability to autorun code stored on the USB memory, allow workers to not only take data with them but also carry around their preferred applications.
Many worms have done an end run around a corporate network's perimeter security by hitching a ride on a laptop brought home by a worker. USB smart drives present a similar problem for companies and should be managed in a similar way, said Kate Purmal, CEO of U3, a maker of the U3 smart drive platform.
"The right solution for this is the management system used by the company to control the endpoints should also manage the USB ports," Purmal said. "The company should have security at each endpoint that prevents a vanilla device from off the street being plugged into the computer."
Purmal stressed that corporate security managers should not focus on a single scenario, but also consider other issues, such as protecting information on USB drives lost by employees and preventing viruses from being transported from a worker's home computer into the office on USB drives. Companies considering allowing USB drives should create policies that mandate encryption, allow centralised management of the USB ports on every computer, protect desktops with anti-virus and anti-spyware tools, and potentially adopt technology to erase data on USB drives that have been lost or stolen.
Specific industries, such as finance and healthcare, may also need to account for what data was copied to a particular USB drive, AdvancedForce's Chernavsky said.
"If you give someone permission to use a thumb drive, you need to be able to track what data they move to it," he said.
Moreover, the policies and audit functionality need to stand up to even a savvy user sitting at the keyboard, said Dor Skuler, vice president of business development for device-security software maker Safend.
"You want to make sure that the policies cannot be uninstalled," Skuler said.
However, as the attack on the credit union shows, a malicious insider is not necessary if a Trojan horse can be delivered inside the company by an unwitting employee.
Even the most trustworthy employees could fall prey to tactics such as those employed by Secure Network Technologies. A USB drive has allure for some people, not only because the data stored on the drive might pique a person's curiosity, but also because the memory can be reused.
Those twin lures of curiosity and utility, in the end, make USB drives a powerful Trojan horse, Secure Network Technologies' Stasiukonis said.
"Social engineering is always the easiest way to compromise a network, because people are typically very friendly and trusting," he said.
This article originally appeared in Security Focus.
Copyright © 2006, SecurityFocus