How Flame Hid In Plain Sight For Years

One of the most striking aspects about the newly discovered Flame malware kit is its ordinary appearance -- which is what helped make it so elusive for years.

As security researchers dig deeper into the massive lines of code that make up this targeted attack threat discovered this month, the fact that this dangerous cyberespionage kit evaded security controls for so long demonstrates how its similar structure to a commercial software program and its use of off-the-shelf techniques, such as SSL, SSH, and a SQL database, helped it blend in with other application traffic.

Flame has been around for a minimum of two-plus years, and up to eight years, according to some new analysis. It was highly targeted, infecting no more than 1,000 users, mostly in Iran, but also a few infections in other parts of the Middle East, Africa, and Hungary. And it's basically a virtual, digitized spy tool that does what a human spy would do: recording phone calls, snapping photos, and siphoning information.

Given that the majority of its targets were computers in Iran, where pirated software is rampant, it was likely easy for the attacks to bypass security controls, if there were any at all, experts say. "It was probably put on systems that don't have antivirus or was bypassing AV in a direct attack," says Stephen Cobb, security evangelist for ESET. Flame looks a lot like a normal software program, with standard libraries and unremarkable traffic. Actions such as turning on the computer's microphone for recording voice calls and meetings wouldn't necessarily raise suspicion, for instance, security experts say.

Lance James, director of intelligence at Vigilant, considers Flame the most complicated piece of malware ever written. But features such as Flame's encryption are simplified in order to remain under the radar, he says. "My theory is that they were not designed to be unbreakable encryption," James says. Flame contains five encryption ciphers, most of which are easily cracked, he adds.

That's not typical of malware. Most sophisticated malware employs stronger encryption, but the trade-off for the attacker is that its traffic can trigger a red flag at the network layer. "Entropy and complexity is used by most [malware developers]," James says. "In the world of encryption detection of malware at the network layer ... you watch the traffic generated by it and if the measure of randomness/entropy is high," that could be a sign of malware with crypto, he says.

Flame's creators either used easily cracked encryption to camouflage the attack, or it could be a function of the size of the overall code, he says. "They didn't want you to detect that they were hiding anything. They wanted to look like common data," James says. "It did the opposite of what everyone is expecting with malware. And that's what helped it stay undetected for so long."

Then there's the issue of trade sanctions against Iran. The U.S. and other nations are banned from selling certain technology to Iran, including antivirus software. So if users there pirated versions, they aren't likely getting security updates, experts say.

"These regions tend to perform more poorly than the average on an AV solution deployment," says Gunter Ollmann, vice president of research at Damballa. "I'm sure one of the criteria [in an attack] was whether or not there were security products on the targeted device and if it's capable of detecting [Flame's] bag of tricks."

But what worries security experts most is what the next version of Flame will do. Now that the cat's out of the bag, its developers could create new versions, and copycats could emerge. "It's a framework. I wouldn't be surprised to see it going around again," James says. "It's designed like a software house would do."

Francis Cianfrocca, founder and CEO of Bayshore Networks, says there are possibly dozens of precursors and descendants of Flame at large that haven't been detected because they haven't triggered any alarms. And it's a platform that could be used for any type of targeted advanced persistent threat (APT)-type attack, which should worry businesses in the U.S., too.

[ With conventional wisdom now that 'advanced attacks happen,' has the time come to create the next-generation sandbox or other containment method? See Advanced Attacks Call For New Defenses. ]

"With an APT, the value of having a platform like Flame is that it appears to be a platform. It looks to have the novel ability of controlling the I/O on an endpoint by taking over Bluetooth" and other features, Cianfrocca says. "It's the perfect thing if you want to eavesdrop on someone directly."

What's more worrisome is the ability of another version of Flame that could launch attacks within a corporation, he says. "This is a platform constructed in a sophisticated way to allow more than one kind of attack," he says.

Have a comment on this story? Please click "Add Your Comment" below. If you'd like to contact Dark Reading's editors directly, send us a message.