User Beware: The Fine Line Between Content And Code

March 25, 2024 by Tom Nardi 30 Comments

Everyone loves themes. Doesn’t matter if it’s a text editor or a smart display in the kitchen, we want to be able to easily customize its look and feel to our liking. When setting up a new device or piece of software, playing around with the available themes may be one of the first things you do without giving it much thought. After all, it’s not like picking the wrong one is going to do something crazy like silently delete all the files on your computer, right?

Unfortunately, that’s exactly what happened a few days ago to [JeansenVaars] while trying out a Plasma Global Theme from the KDE Store. According to their Reddit post, shortly after installing the “Gray Layout” theme for the popular Linux graphical environment, the system started behaving oddly and then prompted for a root password. Realizing something didn’t seem right they declined, but at that point, it was already too late for all of the personal files in their home directory.

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This Week In Security: Loop DOS, Flipper Responds, And More!

March 22, 2024 by Jonathan Bennett 8 Comments

Here’s a fun thought experiment. UDP packets can be sent with an arbitrary source IP and port, so you can send a packet to one server, and could aim the response at another server. What happens if that response triggers another response? What if you could craft a packet that continues that cycle endlessly? That is essentially the idea behind Loop DoS (Denial of Service).

This unique avalanche of packets has been managed using specific implementations of several different network services, like TFTP, DNS, and NTP. There are several CVEs being used to track the issue, but CVE-2024-2169 is particularly odd, with the description that “Implementations of UDP application protocol are vulnerable to network loops.” This seems to be a blanket CVE for UDP, which is particularly inappropriate given that the first DoS of this sort was first reported in 2009 at the latest.

More details are available in a Google Doc. There some interesting tidbits there, like the existence of cross-protocol loops, and several legacy protocols that are vulnerable by design. The important thing to remember here is you have to have an accessible UDP port for this sort of attack to take place, so if you’re not using it, firewall it.

Flipper Flips Back

We’ve covered the saga of the Flipper Zero vs the Canadian government, in the context of car theft. The short version is that Canada has seen an uptick of car thefts from organized crime. Rather than meaningfully dealing with this problem, the Canadian government went looking for scapegoats, and found the Flipper Zero.

Well now, Flipper has responded, and put simply, the message is “stop the madness”. There has never been a confirmed case of using a flipper to steal a car, and it’s very unlikely it’s ever happened. On a modern car with proper rolling-code security, it’s not meaningfully possible to use the Flipper Zero for the theft. The two primary ways criminals actually steal cars are with dedicated keyfob repeaters and CAN bus hackers.

There is a petition to sign, and for Canadians, Flipper suggests contacting your local member of parliament. Continue reading “This Week In Security: Loop DOS, Flipper Responds, And More!” →

Photoresistors Provide Air Gap Data Transfer, Slowly

March 19, 2024 by Bryan Cockfield 50 Comments

One of the simplest ways of keeping a computer system secure is by using an air gap — that is, never actually connecting the system to the network. This can often include other peripherals like USB drives and other removable storage as well, so getting information to and from secure (or compromised) systems behind air gaps can often present a challenge. But assuming you have local access to the computer and your parts bin handy, these optical solutions from [Nikolay] can allow data transfer to or from such off-line computers.

[Nikolay]’s specific use case for this project is to transfer small amounts of information to or from computers that may be compromised in some way, or computers that might otherwise be dangerous to connect to other equipment. There’s actually several methods described in the project, the first involves temporarily attaching a photoresistor to the computer’s screen which has been wired into the remains of a USB keyboard. A script running on the compromised machine translates data into a series of white and black squares. The sensors can detect these patterns much like playing Duck Hunt on an old CRT television and transmit the data across the air gap with reasonable certainty nothing harmful crossed with it.

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This Week In Security: Apple Backdoors Curl, Tor’s New Bridge, And GhostRace

March 15, 2024 by Jonathan Bennett 8 Comments

OK, that headline is a bit of a cheap shot. But if you run the curl binary that Apple ships, you’re in for a surprise if you happen to use the --cacert flag. That flag specifies that TLS verification is only to be done using the certificate file specified. That’s useful to solve certificate mysteries, or to make absolutely sure that you’re connecting to the server you expect.

What’s weird here is that on a MacOS, using the Apple provided curl binary, --cacert doesn’t limit the program to the single certificate file. On an Apple system, the verification falls back to the system’s certificate store. This is an intentional choice by Apple, but not one that’s aimed particularly at curl. The real magic is in Apple’s SSL library, which forces the use of the system keychain.

The current state of things is that this option is simply not going to do the right thing in the Apple provided binary. It’s documented with the note that “this option is supported for backward compatibility with other SSL engines, but it should not be set.” It’s an unfortunate situation, and we’re hopeful that a workaround can be found to restore the documented function of this option. Continue reading “This Week In Security: Apple Backdoors Curl, Tor’s New Bridge, And GhostRace” →

This Week In Security: Blame The Feds, Emergency Patches, And The DMA

March 8, 2024 by Jonathan Bennett No comments

The temptation to “take the money and run” was apparently too much for the leadership of the AlphV ransomware crime ring. You may have heard of this group as being behind the breach of Change Healthcare, and causing payment problems for nearly the entire US Healthcare system. And that hack seems to be key to what’s happened this week.

It’s known that a $22 million payment made it through the bitcoin maze to the AlphV wallet on the 1st. It’s believed that this is a payment from Change Healthcare to recover ransomed files. An important detail here is that AlphV is a ransomware-as-a-service provider, and the actual hacking is done by “affiliates”, who use that service, and AlphV handles the infrastructure, maintaining the actual malware, and serving as a payment processor. That last one is key here.

A couple days after that big payment landed in the AlphV account, a seizure notice went up on the AlphV TOR site, claiming that it had been taken down by the FBI and associated agencies. There was something a bit odd about it, though. See, the FBI did seize the AlphV Tor site back in December. The seizure notice this time was an exact copy, as if someone had just done a “save page as”, and posted the copy.

There is precedent for a ransomware group to close up shop and disappear after hitting a big score. The disruption AlphV enabled in the US health care system painted a big target on them, and it didn’t take a tactical genius to realize it might be good to lay low for a while. Pocketing the entire $22 million ransom probably didn’t hurt either. The particularly nasty part is that the affiliate that actually pulled off the attack still claims to have four terabytes of sensitive data, and no incentive to not release it online. It’s not even entirely clear that Change Healthcare actually received a decryption key for their data. You do not want to deal with these people.

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Extracting SecOC Keys From A 2021 Toyota RAV4 Prime

March 8, 2024 by Maya Posch 7 Comments

With the recently introduced SecOC (Secure Onboard Communication) standard, car manufacturers seek to make the CAN bus networks that form the backbone of modern day cars more secure. This standard adds a MAC (message authentication code) to the CAN messages, which can be used to validate that these messages come from a genuine part of the car, and not from a car thief or some third-party peripheral.

To check that it isn’t possible to circumvent SecOC, [Willem Melching] and [Greg Hogan] got their hands on the power steering (EPS) unit of a Toyota RAV4 Prime, as one of the first cars to implement this new security standard.

As noted by [Willem], the ultimate goal is to be able to run the open source driver assistance system openpilot on these SecOC-enabled cars, which would require either breaking SecOC, or following the official method of ‘rekeying’ the SecOC gateway.

After dumping the firmware of the EPS Renesas RH850/P1M-E MCU via a voltage fault injection, the AES-based encryption routines were identified, but no easy exploits found in the main application. This left the bootloader as the next target.

Ultimately they managed to reverse-engineer the bootloader to determine how the update procedure works, which enabled them to upload shellcode. This script then enabled them to extract the SecOC keys from RAM and send these over the CAN bus. With these keys the path is thus opened to allow any device to generate CAN messages with valid SecOC MACs, effectively breaking encryption. Naturally, there are many caveats with this discovery.

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A multifactor authentication device showing TOTP codes

An ESP32 MultiFactor TOTP Generator

March 7, 2024 by Dave Rowntree 22 Comments

MFA, or multifactor authentication, is a standard security feature these days. However, it can be a drag to constantly reach into one’s pocket, scroll to Google Authenticator (other MFA applications are available!), and find the correct TOTP code to log in to a site for a short while. [Allan Oricil] felt this pain point, so they took the problem by the horns and created a desktop MFA TOTP generator to make life just that little bit easier.

TOTP, which stands for Time-based One-Time Password, is a security measure that uses a device or application to provide unique codes that expire after a short time. Two-factor authentication requires a physical item (something you have), such as a key or swipe card, and knowledge of a fact (something you know), like a password, rather than relying on a single factor. This approach ensures a higher level of security. [Allan]’s project is a physical thing one would use with a password or key file.

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