FortiOS Vulnerability Alert: Patch Now or Risk an “Old School” Hacker’s Playground!

FortiOS users, beware the chunky exploit! CVE-2024-21762 plays hard to get, requiring assembly chops for a successful hack. Patched but not forgotten, this digital loophole is the nerdy cousin of the buffer overflow family. Patch or risk an uninvited memory party! #FortinetFumble

Hot Take:

Looks like Fortinet’s FortiOS decided to throw a ’90s-themed cybersecurity party, and everyone’s invited—especially those nostalgic for the days of out-of-bounds write vulnerabilities with a side of chunky memory manipulation. Patch your systems, folks, or risk being the victim of a very retro hack!

Key Points:

  • An exploit for CVE-2024-21762 affecting Fortinet’s FortiOS appeared on GitHub, after a patch had been available for over a month.
  • This is an old-school out-of-bounds write vulnerability, so dust off your assembly language textbooks.
  • Chunked encoding, rather than a simple “Content-Length” header, is the culprit for triggering the vulnerability.
  • Scans for the vulnerability are limited, suggesting either low interest from attackers or a preference for easier targets.
  • Only one actor seems to be scanning for this vulnerability, but don’t let that fool you into a false sense of security.
Cve id: CVE-2023-27997
Cve state: PUBLISHED
Cve assigner short name: fortinet
Cve date updated: 06/13/2023
Cve description: A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.

Cve id: CVE-2024-21762
Cve state: PUBLISHED
Cve assigner short name: fortinet
Cve date updated: 02/09/2024
Cve description: A out-of-bounds write in Fortinet FortiOS versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.6, 7.0.0 through 7.0.13, 6.4.0 through 6.4.14, 6.2.0 through 6.2.15, 6.0.0 through 6.0.17, FortiProxy versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.8, 7.0.0 through 7.0.14, 2.0.0 through 2.0.13, 1.2.0 through 1.2.13, 1.1.0 through 1.1.6, 1.0.0 through 1.0.7 allows attacker to execute unauthorized code or commands via specifically crafted requests

Need to know more?

The Art of Exploitation: Not for Script Kiddies

Imagine a time where exploiting a vulnerability required actual skills rather than a copy-paste from Stack Overflow. Well, CVE-2024-21762 is bringing back those days in full force, requiring attackers to actually understand assembly language to craft a working exploit. So, if you see someone scanning your network for this vulnerability, they're probably not your average spray-and-pray hacker but rather someone who could actually give Neo a run for his money in a hacking showdown.

Chunky Soup for the Hacker's Soul

The exploit works by manipulating the 'chunky' encoding of HTTP request bodies, a method that's given developers headaches since the dial-up era. Instead of using a simple Content-Length header, chunked encoding breaks down data into pieces, and it's this breaking down that's giving Fortinet's FortiOS a breakdown of its own.

Setting the Stage for a Cyber Heist

To exploit this vulnerability, an attacker has to set the stage by allocating the right amount of memory, like a meticulous bank robber planning their route. This is done by sending a specific form data to the URL "/remote/hostcheck_validate". And this URL is not just any URL—it's like the secret backdoor that's also an unintentional honeypot detector. Crafty, right?

Scanning for Gold—or Not

When it comes to scanning for this vulnerability, things have been quieter than a library on a Friday night. There's been some light scanning activity, but it's more like a lone wolf situation with just one actor from an IP address that's probably been used more for scanning than a supermarket barcode reader. These scans are looking for a buffet of vulnerabilities, not just FortiOS, so it's like they're at an all-you-can-exploit buffet.

Popularity Contest: CVE Edition

Despite being the belle of the ball in terms of complexity, CVE-2024-21762 hasn't been getting much love from attackers. Maybe it's because there are easier fish to fry, or perhaps because hacking isn't as fun when it requires actual work. Still, just because it's not the most popular kid on the block doesn't mean you can ignore it. Unpatched systems are like houses with the front door wide open—you should assume someone's already taken the TV if you're not up-to-date with your security patches.

Tags: CVE-2024-21762, Exploit Analysis, Fortinet Patch, FortiOS Vulnerability, Heap Overflow, Network Security, Vulnerability Scanning