RCE

2 Articles

This Week In Security: Curl Reveal, Rapid Reset DDoS, And Libcue

October 13, 2023 by 17 Comments

Curl gave us all a big warning that a severe security problem had been found in that code-base. Given the staggering number of Curl installs around the world, we held our collective breath and waited for the bombshell to drop this Wednesday. It turns out, it’s not quite as bad as feared — so long as you don’t have a SOCKS proxy.

In hindsight, shipping a heap overflow in code installed in over twenty billion instances is not an experience I would recommend. — Daniel Stenberg

The trouble started when the SOCKS5 proxy support was converted to a non-blocking implementation. It’s a win for libcurl to work on requests asynchronously, but refactoring code and new features always runs a bit of risk. SOCKS5 proxying has some quirks, like allowing DNS resolution to happen locally or at the proxy. The new async code starts out with:

bool socks5_resolve_local =
(proxytype == CURLPROXY_SOCKS5) ? TRUE : FALSE;

First off, unnecessary ternary is unnecessary. But note that this local variable gets set by the proxytype. If that’s CURLPROXY_SOCKS5_HOSTNAME, then it uses remote resolution. But inherited from old code is a check for a hostname that is too long for a SOCKS request (255 bytes). This code converts back to local resolution in this case.

The important detail here is that this function is now a state machine, that potentially runs multiple times for a single request, to achieve that asynchronous execution. The check for a too-long hostname only happens during the initialization state. Copying the hostname into the buffer happens in a different state. If setting up the connection takes enough time, the function will return and be executed again when something has changed. The ternary check runs again, but not the hostname-too-long. So if set to do remote resolution with a long enough host name, execution slips through this edge case, and the long hostname is copied into a too-small buffer.

It’s safe to assume that this heap overflow can result in arbitrary code execution. The fix has landed in 8.4.0, after being present for 1,315 days. [Daniel] goes ahead and gets ahead of the inevitable suggestion that Curl should be written in rust or another memory-safe language. Curl was started before those alternatives existed, and there is a very slow effort to move portions of the project to memory-safe languages. And you’re welcome to help out. Continue reading “This Week In Security: Curl Reveal, Rapid Reset DDoS, And Libcue” →

This Week In Security: USB Cable Kia, Reddit, And Microsoft RCEs

February 17, 2023 by 14 Comments

There is vulnerability in many Hyundai and Kia vehicles, where the ignition switch can be bypassed with a USB cable. And it’s getting a patch rollout right now, but it’s not a USB vulnerability, in quite the way you might think. In most cars, the steering column is easily disassembled, but these vehicles have an extra-bad design problem. The ignition cylinder can be disassembled while locked, just by depressing a pin.

Physical security has some parallels to computer security, and one such parallel is that good security can often be bypassed by a simple mistake. When it comes to lock design, one such potential bypass is the ability to disassemble a lock while it’s still locked. And somehow, Kias after 2010, and Hyundais after 2015 were made with exactly this flaw. The lock could be disassembled, and the interface between the lock and the ignition switch just happens to be the right shape and size for USB A. Oh, and these cars don’t have an engine immobilizer — there isn’t a chip built into the keys for extra security.

The problem became widespread late last year when the flaw went viral on TikTok, and thousands of copycat crimes were inspired. Beyond the obvious problem, that teenagers were getting an early start on a life of crime with grand theft auto, there were at least 8 deaths directly attributed to the inane stunt. And this brings us back to this week’s news, that a software update is rolling out to address the issue.

Honestly, I have questions. A software update doesn’t add in-key security chips. At best, it could attempt to detect the key position, and sabotage the engine management control, in an ad-hoc immobilizer. That’s likely a paper clip-turned-jumper away from being bypassed. The other new feature, doubling the alarm time from 30 second to a minute, doesn’t inspire much confidence. Hopefully the changes are enough to kill the trend. Continue reading “This Week In Security: USB Cable Kia, Reddit, And Microsoft RCEs” →