Tag: black hat

Finally, HID says that “to its knowledge,” none of its encoder keys have leaked or been distributed publicly, and “none of these issues have been exploited at customer locations and the security of our customers has not been compromised.”

Javadi counters that there’s no real way to know who might have secretly extracted HID’s keys, now that their method is known to be possible. “There are a lot of smart people in the world,” Javadi says. “It’s unrealistic to think we’re the only people out there who could do this.”

Despite HID’s public advisory more than seven months ago and the software updates it released to fix the key-extraction problem, Javadi says most of the clients whose systems he’s tested in his work don’t appear to have implemented those fixes. In fact, the effects of the key extraction technique may persist until HID’s encoders, readers, and hundreds of millions of keycards are reprogrammed or replaced worldwide.

Time to Change the Locks

To develop their technique for extracting the HID encoders’ keys, the researchers began by deconstructing its hardware: They used an ultrasonic knife to cut away a layer of epoxy on the back of an HID reader, then heated the reader to desolder and pull off its protected SAM chip. Then they put that chip into their own socket to watch its communications with a reader. The SAM in HID’s readers and encoders are similar enough that this let them reverse engineer the SAM’s commands.

Ultimately, that hardware hacking allowed them to develop a much cleaner, wireless attack: They wrote their own program to tell an encoder to send its SAM’s secrets to a configuration card without encrypting that sensitive data—while an RFID “sniffer” device sat between the encoder and the card, reading HID’s keys in transit.

HID systems and other forms of RFID keycard authentication have, in fact, been cracked repeatedly, in various ways, in recent decades. But vulnerabilities like the ones set to be presented at Defcon may be particularly tough to fully protect against. “We crack it, they fix it. We crack it, they fix it,” says Michael Glasser, a security researcher and the founder of Glasser Security Group, who has discovered vulnerabilities in access control systems since as early as 2003. “But if your fix requires you to replace or reprogram every reader and every card, that’s very different from a normal software patch.”

On the other hand, Glasser notes that preventing keycard cloning represents just one layer of security among many for any high-security facility—and practically speaking, most low-security facilities offer far easier ways to get in, such as asking an employee to hold a door open for you while you have your hands full. “Nobody says no to the guy holding two boxes of donuts and a box of coffee,” Glasser says.

Javadi says the goal of their Defcon talk wasn’t to suggest that HID’s systems are particular vulnerable—in fact, they say they focused their years of research on HID specifically because of the challenge of cracking its relatively secure products—but rather to emphasize that no one should depend on any single technology for their physical security.

Now that they have made clear that HID’s keys to the kingdom can be extracted, however, the company and its customers may nonetheless face a long and complicated process of securing those keys again. “Now customers and HID have to claw back control—and change the locks, so to speak,” Javadi says. “Changing the locks is possible. But it’s going to be a lot of work.”

Researchers have long known that they can glean hidden information about the inner workings of a website by measuring the amount of time different requests take to be fulfilled and extrapolating information—and potential weaknesses—from slight variations. Such “web timing attacks” have been described for years, but they would often be too involved for real-world attackers to utilize in practice even if they work in theory. At the Black Hat security conference in Las Vegas this week, though, one researcher warned that web timing attacks are actually feasible and ripe for exploitation.

James Kettle, director of research at the web application security company PortSwigger, developed a set of web timing attack techniques that can be used to expose three different categories of vulnerabilities in websites. He validated the methods using a test environment he made that compiled 30,000 real websites, all of which offer bug bounty programs. He says the goal of the work is to show that once someone has a conceptual grasp on the types of information web timing attacks can deliver, taking advantage of them becomes more feasible.

“I’ve always kind of avoided researching timing attacks because it’s a topic with a reputation,” Kettle says. “Everyone does research into it and says their research is practical, but no one ever seems to actually use timing attacks in real life, so how practical is it? What I’m hoping this work will do is show people that this stuff does actually work these days and get them thinking about it.”

Kettle was inspired in part by the 2020 research paper titled “Timeless Timing Attacks,” which worked toward a solution for a common issue. Known as “network jitter,” the paper’s moniker refers to time delays between when a signal is sent and received on a network. These fluctuations impact timing measurements, but they are independent of the web server processing measured for timing attacks, so they can distort readings. The 2020 research, though, pointed out that when sending requests over the ubiquitous HTTP/2 network protocol, it is possible to put two requests into a single TCP communication packet so you know that both requests arrived at the server at the same time. Then, because of how HTTP/2 is designed, the responses will come back ordered so that the one that took less time to process is first and the one that took longer is second. This gives reliable, objective information about timing on the system without requiring any extra knowledge of the target web server—hence, “timeless timing attacks.”

Web timing attacks are part of a class of hack known as “side channels” in which the attacker gathers information about a target based on its real world, physical properties. In his new work, Kettle refined the “timeless timing attacks” technique for reducing network noise and also took steps to address similar types of issues with server-related noise so his measurements would be more accurate and reliable. He then started using timing attacks to look for otherwise invisible coding errors and flaws in websites that are usually difficult for developers or bad actors to find, but that are highlighted in the information that leaks with timing measurements.

In addition to using timing attacks to find hidden footholds to attack, Kettle also developed effective techniques for detecting two other common types of exploitable web bugs. One, known as a server-side injection vulnerability, allows an attacker to introduce malicious code to send commands and access data that shouldn’t be available. And the other, called misconfigured reverse proxies, allows unintended access to a system.

In his presentation at Black Hat on Wednesday, Kettle demonstrated how he could use a web timing attack to uncover a misconfiguration and ultimately bypass a target web application firewall.

“Because you found this inverse proxy misconfiguration you just go around the firewall,” he told WIRED ahead of his talk. “It’s absolutely trivial to execute once you’ve found these remote proxies, and timing attacks are good for finding these issues.”

Alongside his talk, Kettle released functionality for the open source vulnerability scanning tool known as Param Miner. The tool is an extension for the popular web application security assessment platform Burp Suite, which is developed by Kettle’s employer PortSwigger. Kettle hopes to raise awareness about the utility of web timing attacks, but he also wants to make sure the techniques are being utilized for defense even when people don’t grasp the underlying concepts.

“I integrated all these new features into Param Miner so people out there who don’t know anything about this can run this tool and find some of these vulnerabilities,” Kettle says. “It’s showing people things that they would have otherwise missed.”