MSG_PEEK is pretty common, CVE-2016-10229 is worse than you think April 13, 2017 on Drew DeVault's blog

I heard about CVE-2016-10229 earlier today. In a nutshell, it allows for arbitrary code execution via UDP traffic if userspace programs are using MSG_PEEK in their recv calls. I quickly updated my kernels and rebooted any boxes where necessary, but when I read the discussions on this matter I saw people downplaying this issue by claiming MSG_PEEK is an obscure feature.

I don’t want to be a fear monger and I’m by no means a security expert but I suspect that this is a deeply incorrect conclusion. If I understand this vulnerability right you need to drop everything and update any servers running a kernel <4.5 immediately. MSG_PEEK allows a programmer using UDP to read from the kernel’s UDP buffer without consuming the data (so subsequent reads will continue to read the same data). This immediately sounds to me like a pretty useful feature that a lot of software might use, not an obscure one.

I did quick search for software where MSG_PEEK appears in the source code somewhere. This does not necessarily mean that it’s exploitable, but should certainly raise red flags. Here’s a list of some notable software I found:

I also found a few things like programming languages and networking libraries that you might expect to have MSG_PEEK if only to provide that functionality to programmers leveraging them. I didn’t investigate too deeply into whether or not that was the case or if this software is using the feature in a less apparent way, but in this category I found Python, Ruby, Node.js, smalltalk, octave, libnl, and socat. I used searchcode.com to find these - here’s the full search results.

Again, I’m not a security expert, but I’m definitely spooked enough to update my shit and I suggest you do so as well. Red Hat, Debian, and Ubuntu are all unaffected because of the kernel they ship. Note, however, that many cloud providers do not let you choose your own kernel. This could mean that you are affected even if you’re running a distribution like Debian. Double check it - use uname -r and update+reboot if necessary.

Have a comment on one of my posts? Start a discussion in my public inbox by sending an email to ~sircmpwn/public-inbox@lists.sr.ht [mailing list etiquette]

Articles from blogs I read Generated by openring

Command PATH security in Go

Today’s Go security release fixes an issue involving PATH lookups in untrusted directories that can lead to remote execution during the go get command. We expect people to have questions about what exactly this means and whether they might h…

via The Go Programming Language Blog January 19, 2021

Status update, January 2021

Hi all! This month again, my main focus has been wlroots. I’ve focused on the internal renderer refactoring (the so-called “renderer v6"). A lot of the work has now been completed, and all backends now use the new interfaces under-the-hood. With the help …

via emersion January 18, 2021

What's cooking on Sourcehut? January 2021

Another year begins, and hopefully with better prospects for us all. SourceHut has emerged from 2020 relatively unscathed, thankfully, and I hope the same is true of most of our users. A body which, by the way, today numbers 19,647 strong, up 623 from Decemb…

via Blogs on Sourcehut January 15, 2021