Author: Jonathan Bennett

450 Articles

This Week In Security: Rsync, SSO, And Pentesting Mushrooms

January 17, 2025 by 14 Comments

Up first, go check your machines for the rsync version, and your servers for an exposed rsync instance. While there are some security fixes for clients in release 3.4.0, the buffer overflow in the server-side rsync daemon is the definite standout. The disclosure text includes this bit of nightmare fuel: “an attacker only requires anonymous read access to a rsync server, such as a public mirror, to execute arbitrary code on the machine the server is running on.”

A naive search on Shodan shows a whopping 664,955 results for rsync servers on the Internet. Red Hat’s analysis gives us a bit more information. The checksum length is specified by the remote client, and an invalid length isn’t properly rejected by the server. The effect is that an attacker can write up to 48 bytes into the heap beyond the normal checksum buffer space. The particularly dangerous case is also the default: anonymous access for file retrieval. Red Hat has not identified a mitigation beyond blocking access.

If you run servers or forward ports, it’s time to look at ports 873 and 8873 for anything listening. And since that’s not the only problem fixed, it’s really just time to update to rsync 3.4.0 everywhere you can. While there aren’t any reports of this being exploited in the wild, it seems like attempts are inevitable. As rsync is sometimes used in embedded systems and shipped as part of appliances, this particular bug threatens to have quite the long tail. Continue reading “This Week In Security: Rsync, SSO, And Pentesting Mushrooms” →

This Week In Security: Backdoored Backdoors, Leaking Cameras, And The Safety Label

January 10, 2025 by 3 Comments

The mad lads at watchTowr are back with their unique blend of zany humor and impressive security research. And this time, it’s the curious case of backdoors within popular backdoors, and the list of unclaimed domains that malicious software would just love to contact.

OK, that needs some explanation. We’re mainly talking about web shells here. Those are the bits of code that get uploaded to a web server, that provide remote access to the computer. The typical example is a web application that allows unrestricted uploads. If an attacker can upload a PHP file to a folder where .php files are used to serve web pages, accessing that endpoint runs the arbitrary PHP code. Upload a web shell, and accessing that endpoint gives a command line interface into the machine.

The quirk here is that most attackers don’t write their own tools. And often times those tools have special, undocumented features, like loading a zero-size image from a .ru domain. The webshell developer couldn’t be bothered to actually do the legwork of breaking into servers, so instead added this little dial-home feature, to report on where to find all those newly backdoored machines. Yes, many of the popular backdoors are themselves backdoored.

This brings us to what watchTowr researchers discovered — many of those backdoor domains were either never registered, or the registration has been allowed to expire. So they did what any team of researchers would do: Buy up all the available backdoor domains, set up a logging server, and just see what happens. And what happened was thousands of compromised machines checking in at these old domains. Among the 4000+ unique systems, there were a total of 4 .gov. domains from governments in Bangladesh, Nigeria, and China. It’s an interesting romp through old backdoors, and a good look at the state of still-compromised machines.

Continue reading “This Week In Security: Backdoored Backdoors, Leaking Cameras, And The Safety Label” →

FLOSS Weekly Episode 815: You Win Some, You Lose Some

January 8, 2025 by 2 Comments

This week, Jonathan Bennett and Randal chat with Matija Šuklje about Open Source and the Law! How do Open Source projects handle liability, what should a Contributor License Agreement (CLA) look like, and where can an individual or project turn for legal help?

Continue reading “FLOSS Weekly Episode 815: You Win Some, You Lose Some” →

This Week In Security: IOCONTROL, (Location) Leaking Cars, And Passkeys

January 3, 2025 by 11 Comments

Claroty’s TEAM82 has a report on a new malware strain, what they’re calling IOCONTROL. It’s a Linux malware strain aimed squarely at embedded devices. One of the first targets of this malware, surprisingly, is the Iraeli made Orpak gas station pumps. There’s a bit of history here, as IOCONTROL is believed to be used by CyberAv3ngers, a threat actor aligned with Iran. In 2023 a group aligned with Israel claimed to have compromised the majority of the gas stations in Iran. IOCONTROL seems to have been deployed as retribution.

There are a few particularly interesting aspects of this malware, and how TEAM82 went about analyzing it. The first is that they used unicorn to emulate the obscure ARM platform in question. This was quite an adventure, as they were running the malicious binary without the normal Linux OS under it, and had to re-implement system calls to make execution work. The actual configuration data was encrypted as the data section of the executable, presumably to avoid simple string matching detection and analysis.

Then to communicate with the upstream command and control infrastructure, the binary first used DNS-Over-HTTPS to resolve DNS addresses, and then used the MQTT message protocol for actual communications. Once in place, it has the normal suite of capabilities, like code execution, cleanup, lateral scanning, etc. An interesting speculation is that the level of control this malware had over these gas pumps, it was in a position to steal credit card information. This malware family isn’t limited to gas pumps, either, as it’s been spotted in IoT and SCADA devices from a whole host of vendors. Continue reading “This Week In Security: IOCONTROL, (Location) Leaking Cars, And Passkeys” →