Security Hacks

1497 Articles

Screenshot of Linux in a PDF in a browser

Nice PDF, But Can It Run Linux? Yikes!

February 10, 2025 by 21 Comments

The days that PDFs were the granny-proof Swiss Army knives of document sharing are definitely over, according to [vk6]. He has managed to pull off the ultimate mind-bender: running Linux inside a PDF file. Yep, you read that right. A full Linux distro chugging along in a virtual machine all encapsulated within a document. Just when you thought running DOOM was the epitome of it. You can even try it out in your own browser, right here. Mind-boggling, or downright Pandora’s box?

Let’s unpack how this black magic works. The humble PDF file format supports JavaScript – with a limited standard library, mind you. By leveraging this, [vk6] managed to compile a RISC-V emulator (TinyEMU) into JavaScript using an old version of Emscripten targeting asm.js instead of WebAssembly. The emulator, embedded within the PDF, interfaces with virtual input through a keyboard and text box.

The graphical output is ingeniously rendered as ASCII characters – each line displayed in a separate text field. It’s a wild solution but works astonishingly well for something so unconventional.

Security-wise, this definitely raises eyebrows. PDFs have long been vectors for malware, but this pushes things further: PDFs with computational power. We know not to trust Word documents, whether they just capable of running Doom, or trash your entire system in a blink. This PDF anomaly unfolds a complete, powerful operating system in front of your very eyes. Should we think lightly, and hope it’ll lead to smarter, more interactive PDFs – or will it bring us innocent looking files weaponized for chaos?

Curious minds, go take a look for yourself. The project’s code is available on GitHub.

Continue reading “Nice PDF, But Can It Run Linux? Yikes!” →

This Week In Security: Medical Backdoors, Strings, And Changes At Let’s Encrypt

February 7, 2025 by 12 Comments

There are some interesting questions afoot, with the news that the Contec CMS8000 medical monitoring system has a backdoor. And this isn’t the normal debug port accidentally left in the firmware. The CISA PDF has all the details, and it’s weird. The device firmware attempts to mount an NFS share from an IP address owned by an undisclosed university. If that mount command succeeds, binary files would be copied to the local filesystem and executed.

Additionally, the firmware sends patient and sensor data to this same hard-coded IP address. This backdoor also includes a system call to enable the eth0 network before attempting to access the hardcoded IP address, meaning that simply disabling the Ethernet connection in the device options is not sufficient to prevent the backdoor from triggering. This is a stark reminder that in the firmware world, workarounds and mitigations are often inadequate. For instance, you could set the gateway address to a bogus value, but a slightly more sophisticated firmware could trivially enable a bridge or alias approach, completely bypassing those settings. There is no fix at this time, and the guidance is pretty straightforward — unplug the affected devices.

Continue reading “This Week In Security: Medical Backdoors, Strings, And Changes At Let’s Encrypt” →

A Great Use For AI: Wasting Scammers Time!

February 6, 2025 by 62 Comments

We may have found the killer app for AI. Well, actually, British telecom provider O2 has. As The Guardian reports, they have an AI chatbot that acts like a 78-year-old grandmother and receives phone calls. Of course, since the grandmother—Daisy, by name—doesn’t get any real phone calls, anyone calling that number is probably a scammer. Daisy’s specialty? Keeping them tied up on the phone.

While this might just seem like a prank for revenge, it is actually more than that. Scamming people is a numbers game. Most people won’t bite. So, to be successful, scammers have to make lots of calls. Daisy can keep one tied up for around 40 minutes or more.

Continue reading “A Great Use For AI: Wasting Scammers Time!” →

This Week In Security: DeepSeek’s Oopsie, AI Tarpits, And Apple’s Leaks

January 31, 2025 by 8 Comments

DeepSeek has captured the world’s attention this week, with an unexpected release of the more-open AI model from China, for a reported mere $5 million training cost. While there’s lots of buzz about DeepSeek, here we’re interested in security. And DeepSeek has made waves there, in the form of a ClickHouse database unintentionally opened to the world, discovered by the folks from Wiz research. That database contained chat history and log streams, and API keys and other secrets by extension.

Finding this database wasn’t exactly rocket science — it reminds me of my biggest bug bounty win, which was little more than running a traceroute and a port scan. In this case it was domain and sub domain mapping, and a port scan. The trick here was knowing to try this, and then understanding what the open ports represented. And the ClickHouse database was completely accessible, leaking all sorts of sensitive data. Continue reading “This Week In Security: DeepSeek’s Oopsie, AI Tarpits, And Apple’s Leaks” →

This Week In Security: ClamAV, The AMD Leak, And The Unencrypted Power Grid

January 24, 2025 by 10 Comments

Cisco’s ClamAV has a heap-based buffer overflow in its OLE2 file scanning. That’s a big deal, because ClamAV is used to scan file attachments on incoming emails. All it takes to trigger the vulnerability is to send a malicious file through an email system that uses ClamAV.

The exact vulnerability is a string termination check that can fail to trigger, leading to a buffer over-read. That’s a lot better than a buffer overflow while writing to memory. That detail is why this vulnerability is strictly a Denial of Service problem. The memory read results in process termination, presumably a segfault for reading protected memory. There are Proof of Concepts (PoCs) available, but so far no reports of the vulnerability being used in the wild.
Continue reading “This Week In Security: ClamAV, The AMD Leak, And The Unencrypted Power Grid” →

Bambu Connect’s Authentication X.509 Certificate And Private Key Extracted

January 19, 2025 by 125 Comments

Hot on the heels of Bambu Lab’s announcement that it would be locking down all network access to its X1-series 3D printers with new firmware, the X.509 certificate and private key from the Bambu Connect application have now been extracted by [hWuxH]. This application was intended to be the sole way for third-party software to send print jobs to Bambu Lab hardware as we previously reported.

The Bambu Connect app is a fairly low-effort Electron-based affair, with some attempt at obfuscation and encryption, but not enough to keep prying eyes out. The de-obfuscated main.js file can be found here (archived), with the certificate and private key clearly visible. These are used to encrypt HTTP traffic with the printer, and is the sole thing standing in the way of tools like OrcaSlicer talking with authentication-enabled Bambu Lab printers.

As for what will be the next steps by Bambu Lab, it’s now clear that security through obfuscation is not going to be very effective here. While playing whack-a-mole with (paying) users who are only interested in using their hardware in the way that they want is certainly an option, this might be a wake-up call for the company that being more forthcoming with their userbase would be in anyone’s best interest.

We await Bambu Lab’s response with bated breath.

New Bambu Lab Firmware Update Adds Mandatory Authorization Control System

January 17, 2025 by 105 Comments

As per a recent Bambu Lab blog post, its FDM printers in the X1 series will soon receive a firmware update that adds mandatory authentication for certain operations, starting with the firmware update on January 23rd for the aforementioned FDM printers. These operations include performing firmware upgrades, initiating a print job (LAN or cloud), remote video access and adjusting parameters on the printer. Using the printer directly and starting prints from an SD card are not affected.

As reasoning for this new feature Bambu Lab points to recent exploits that gave strangers access to people’s printers, though cheekily linking to an article on an Anycubic printer exploit. While admittedly a concern, this mostly affects internet-exposed printers, such as those that are tied into a ‘cloud’ account. Even so, LAN-based printing also falls under this new mandatory authentication system, with Bambu Lab offering a new tool called Bambu Connect for those who insist on using non-Bambu Lab branded software like OrcaSlicer. This allows for exported G-code files to be sent to a (property authenticated) Bambu Lab printer.

For those who do not wish to use this feature, not upgrading the firmware is currently the only recourse. Although this firmware update is only for X1-series printers, Bambu Lab promised that it’ll arrive for their other printers too in due time. While Bambu Lab printer owners consider installing the alternative X1 Plus firmware, the peanut gallery can discuss the potential security issues (or lack thereof) of an open Fluidd or similar UI on their LAN-connected, Klipper-based FDM printers.

Thanks to [mip] for the tip.