Bypassing Bitlocker With A Logic Analzyer

August 25, 2023 by Dave Rowntree 27 Comments

Security Engineer [Guillaume Quéré] spends the day penetration testing systems for their employer and has pointed out and successfully exploited a rather obvious weakness in the BitLocker full volume encryption system, which as the linked article says, allows one to simply sniff the traffic between the discrete TPM chip and CPU via an SPI bus. The way Bitlocker works is to use a private key stored in the TPM chip to encrypt the full volume key that in turn was used to encrypt the volume data. This is all done by low-level device drivers in the Windows kernel and is transparent to the user.

TPM chip pins too small? Just find something else on the bus!

The whole point of BitLocker was to prevent access to data on the secured volume in the event of a physical device theft or loss. Simply pulling the drive and dropping it into a non-secured machine or some other adaptor would not provide any data without the key stored by the TPM. However, since that key must pass as plaintext from the TPM to the CPU during the boot sequence, [Guillaume] shows that it is quite straightforward — with very low-cost tools and free software — to simply locate and sniff out this TPM-to-CPU transaction and decode the datastream and locate the key. Using little more than a cheapo logic analyser hooked up to some conveniently large pins on a nearby flash chip (because the SCK, MISO, and MOSI pins are shared with the TPM) the simple TIS was decoded enough to lock onto the bytes of the TPM frame. This could then be decoded with a TPM stream decoder web app, courtesy of the TPM2-software community group. The command to look for is the TPM_CC.Unseal which is the request from the CPU to the TPM to send over that key we’re interested in. After that just grabbing and decoding the TPM response frame will immediately reveal the goods.

Continue reading “Bypassing Bitlocker With A Logic Analzyer” →

This Week In Security: WinRAR, DNS Disco, And No Silver Bullets

August 25, 2023 by Jonathan Bennett 1 Comment

So what does WinRAR, day trading, and Visual Basic have in common? If you guessed “elaborate malware campaign aimed at investment brokers”, then you win the Internet for the day. This work comes from Group-IB, another cybersecurity company with a research team. They were researching a malware known as DarkMe, and found an attack on WinRAR being used in the wild, using malicious ZIP files being spread on a series of web forums for traders.

Among the interesting tidbits of the story, apparently at least one of those forums locked down the users spreading the malicious files, and they promptly broke into the forum’s back-end and unlocked their accounts. The vulnerability itself is interesting, too. A rigged zip file is created with identically named image file and folder containing a script. The user tries to open the image, but because the zip is malformed, the WinRAR function gets confused and opens the script instead.

Based on a user’s story from one of those forums, it appears that the end goal was to break into the brokers’ trading accounts, and funnel money into attacker accounts. The one documented case only lost $2 worth of dogecoin.

There was one more vulnerability found in WinRAR, an issue when processing malicious recovery volumes. This can lead to code execution due to a memory access error. Both issues were fixed with release 6.23, so if you still have a WinRAR install kicking around, make sure it’s up to date! Continue reading “This Week In Security: WinRAR, DNS Disco, And No Silver Bullets” →

Liberté, égalité, Fraternité: France Loses Its Marbles On Internet Censorship

August 22, 2023 by Jenny List 77 Comments

Over the years we’ve covered a lot of attempts by relatively clueless governments and politicians to enact think-of-the-children internet censorship or surveillance legislation, but there’s a law from France in the works which we think has the potential to be one of the most sinister we’ve seen yet.

It flew under our radar so we’re grateful to [0x1b5b] for bringing it to our attention, and it concerns a proposal to force browser vendors to incorporate French government censorship and spyware software in their products. We’re sure that most of our readers will understand the implications of this, but for anyone not versed in online privacy and censorship this is a level of intrusion not even attempted by China in its state surveillance programme. Perhaps most surprisingly in a European country whose people have an often-fractious relationship with their government, very few French citizens seem to be aware of it or what it means.

It’s likely that if they push this law through it will cause significant consternation over the rest of the European continent. We’d expect those European countries with less liberty-focused governments to enthusiastically jump on the bandwagon, and we’d also expect the European hacker community to respond with a plethora of ways for their French cousins to evade the snooping eyes of Paris. We have little confidence in the wisdom of the EU parliament in Brussels when it comes to ill-thought-out laws though, so we hope this doesn’t portend a future dark day for all Europeans. We find it very sad to see in any case, because France on the whole isn’t that kind of place.

Header image: Pierre Blaché CC0.

This Week In Security: TunnelCrack, Mutant, And Not Discord

August 18, 2023 by Jonathan Bennett 10 Comments

Up first is a clever attack against VPNs, using some clever DNS and routing tricks. The technique is known as TunnelCrack (PDF), and every VPN tested was vulnerable to one of the two attacks, on at least one supported platform.
Continue reading “This Week In Security: TunnelCrack, Mutant, And Not Discord” →

This Week In Security: It’s Con Season

August 11, 2023 by Jonathan Bennett 8 Comments

It must be Blackhat/DEFCON season. Up first in the storm of named vulnerabilities, we have Downfall. The PDF has the juicy details here. It’s quite similar to the Zenbleed issue from last week, in that it abuses speculative execution to leak data via a hidden register. Unlike Zenbleed, this isn’t direct access, but using cache timing analysis to extract individual bytes using a FLUSH+RELOAD approach.

The key to the vulnerability is the gather instruction, which pulls data from multiple locations in memory, often used to run a followup instruction on multiple bytes of data at once. The gather instruction is complex, takes multiple clock cycles to execute, and uses several tricks to execute faster, including managing buffers to avoid multiple reads. In certain cases, that instruction can be interrupted before it completes, leaving the data in the cache. And this data can be speculatively accessed and the values leaked through timing analysis.

This flaw affects 6th generation Intel Core processors through 11th. Mitigations are already rolling out via a microcode update, but do carry a performance hit for gather instructions. Continue reading “This Week In Security: It’s Con Season” →

Noisy Keyboards Sink Ships

August 6, 2023 by Al Williams 40 Comments

Many of us like a keyboard with a positive click noise when we type. You might want to rethink that, though, in light of a new paper from the UK that shows how researchers trained an AI to decode keystrokes from noise on conference calls.

The researchers point out that people don’t expect sound-based exploits. The paper reads, “For example, when typing a password, people will regularly hide their screen but will do little to obfuscate their keyboard’s sound.”

The technique uses the same kind of attention network that makes models like ChatGPT so powerful. It seems to work well, as the paper claims a 97% peak accuracy over both a telephone or Zoom. In addition, where the model was wrong, it tended to be close, identifying an adjacent keystroke instead of the correct one. This would be easy to correct for in software, or even in your brain as infrequent as it is. If you see the sentence “Paris im the s[ring,” you can probably figure out what was really typed.

We’ve seen this done before, but this technique raises the bar. As sophisticated as keyboard listening was back in the 1970s, you can only imagine what the three-letter agencies can do these days.

In the meantime, the mitigation for this particular threat seems obvious — just start screaming whenever you type in your password.

This Week In Security: Your Car’s Extended Warranty, Seizing The Fediverse, And Arm MTE

August 4, 2023 by Jonathan Bennett 15 Comments

If you’ve answered as many spam calls as I have, you probably hear the warranty scam robocall in your sleep: “We’ve been trying to reach you about your car’s extended warranty.” That particular robocalling operation is about to run out of quarters, as the FCC has announced a nearly $300 million fine levied against that particular operation. The scammers had a list of 500 million phone numbers, and made over five billion calls in three months. Multiple laws were violated, including some really scummy behavior like spoofing employer caller ID, to try to convince people to pick up the call.

Now, that record-setting fine probably isn’t ever going to get paid. The group of companies on the hook for the amount don’t really exist in a meaningful way. The individuals behind the scams are Roy Cox and Aaron Jones, who have already been fined significant amounts and been banned from making telemarketing calls. Neither of those measures put an end to the problem, but going after Avid Telecom, the company that was providing telephone service, did finally put the scheme down.

Mastodon Data Scooped

There are some gotchas to Mastodon. Direct Messages aren’t end-to-end encrypted, your posts are publicly viewable, and if your server operator gets raided by law enforcement, your data gets caught up in the seizure.

The background here is the administrator of the server in question had an unrelated legal issue, and was raided by FBI agents while working on an issue with the Mastodon instance. As a result, when agents seized electronics as evidence, a database backup of the instance was grabbed too. While Mastodon posts are obviously public by design, there is some non-public data to be lost. IP addresses aren’t exactly out of reach of law enforcement, it’s still a bit of personal information that many of us like to avoid publishing. Then there’s hashed passwords. While it’s better than plaintext passwords, having your password hash out there just waiting to be brute-forced is a bit disheartening. But the one that really hurts is that Mastodon doesn’t have end-to-end encryption for private messages. Continue reading “This Week In Security: Your Car’s Extended Warranty, Seizing The Fediverse, And Arm MTE” →