The RADIUS authentication scheme, short for “Remote Authentication Dial-In User Service”, has been widely deployed for user authentication in a variety of scenarios. It’s a bit strange, because individual users authenticate to a “RADIUS Client”, sometimes also called a Network Access Server (NAS). In response to an authentication request, a NAS packages the authentication data and sends it to a central RADIUS server for verification. The server then sends back a verdict on the authentication request, and if successful, the user is authenticated to the NAS/client.
The scheme was updated to its current form in 1994, when MD5 was still considered a cryptographically sound hash. MD5 has been shown to have problems, most notably a chosen-prefix collision attack that was demonstrated in 2007. The basis of this collision attack is that, given any two messages, it is possible to find a pair of values which, when added to the end of those messages, result in matching md5 hashes for each combined message. It turns out that this is directly applicable to RADIUS.
The attack is a man-in-the-middle, but not against an authenticating user. This attack is a man-in-the-middle between the NAS and the RADIUS server, and a real user is not even required. This elevated position makes an attack harder to execute in some cases, but situations such as RADIUS providing authentication for administrative access to a device clearly fall under this. Wrapping the RADIUS backend communication in a TLS layer protects against the attack.
Gitlab
It’s time to update your Gitlab instances again, and this one sounds familiar. It’s another issue that allows an attacker to run pipeline tasks as an arbitrary user. This is one of many issues in Gitlab, at least one of which is being exploited in the wild. It’s not surprising to see a high-visibility vulnerability lead to the discovery of even more similar issues. Since this latest issue is so similar to the previous pipeline issue, it’s possible that it’s actually an incomplete patch or additional workaround that was discovered to exploit the same issue.
Rash
There is a bug in the Exim mail server that affects the processing of attachment blocking rules. In particular, the file name in the email header is split into multiple parts, with some confusing extra bytes in between. Technically it complies with the correct RFC, but Exim’s mime handling code gets confused and misses the correct message name.
Exim server can be configured to block certain file types, and this vulnerability lets those blocked attachments through. The original CVSS from 9.1 is a bit insane. The latest update drops that to 5.4, which seems much more appropriate.
Mapping your ORM
Prisma is a “Next Generation ORM (Object Relational Mapper)”, which takes a database schema and maps it to code objects. In other words, it helps write code that interacts with a database. There are some potential problems there, such as using filters on protected data to leak information one byte at a time, in a very Hollywood way.
This brings us to a second approach, a time-based data leak. This is where an SQL query is executed slowly or quickly, depending on the data in the database. The plormber tool is designed to easily attempt time-based leaks. Hence the pun. If you have a leak in your ORM, call a plORMber. *sigh*
Internet Explorer rises again
When Microsoft finally made Internet Explorer obsolete in 2022, I held out some hope that it wouldn’t be the source of even more security problems. And yet here we are, in 2024, talking about an exploitation campaign that used a 0-day in Windows to launch Internet Explorer.
A very strange file extension, .pdf.urlmanages to appear as a PDF file with the correct icon, and yet IE opens when executed. This was eventually classified as a vulnerability by Microsoft and fixed.
Bits and bytes
There is another SSH issue, related to regreSSHion. This time a vendor patch calls to cleanup_exit() of a signal handler function, calling more async-unsafe code. If that doesn’t make sense, go back to last week’s installment of the column for the details. This time, it’s Fedora, Red Hat, and other distros that have adopted the patch.
One of the security barriers that most of us rely on is that traffic that comes from the WAN side of the router has to stay there. If that paradigm breaks, we’re in trouble. And that’s exactly what the folks at Claroty are trying to get around. The trick this time is a vulnerability in the Dynamic DNS service of a router. Try to spoof a DNS lookup or MitM that connection and suddenly it’s RCE on the router.
And finally, we’ve covered a couple of notable stories here on Hackaday this week. You should read about how Ticketmaster’s app was reverse engineered , followed by a brilliant and completely impractical plan to get your internet connection for free while flying .