Researchers from software development company JFrog and industrial cybersecurity firm Claroty have identified a total of 14 new vulnerabilities in BusyBox, and on Tuesday they detailed some of their findings.
The security holes found by Claroty and JFrog can be exploited for denial-of-service (DoS) attacks and in some cases they can lead to information disclosure or remote code execution, but they have all been assigned a severity rating of medium and they are unlikely to ever be exploited for malicious purposes.
BusyBox is an open source project that brings together many common Unix tools into a single binary. BusyBox is widely used by embedded devices, including IoT products and industrial control systems (ICS).
There are certain requirements for exploiting the vulnerabilities discovered by Claroty and JFrog, including the attacker being able to control all parameters passed to a vulnerable applet, supplying a specially crafted file, and supplying specially crafted command lines.
Researchers conducted a manual review of the BusyBox source code and leveraged fuzzing to identify the vulnerabilities.
“To assess the threat level posed by these vulnerabilities, we inspected JFrog’s database of more than 10,000 embedded firmware images (composed of only publicly available firmware images, and not ones uploaded to JFrog Artifactory),” the researchers explained. “We found that 40% of them contained a BusyBox executable file that is linked with one of the affected applets, making these issues extremely widespread among Linux-based embedded firmware.”
The researchers noted that while the DoS flaws are easy to exploit, they are mitigated by applets typically running as a separate forked process. They also pointed out that the information disclosure vulnerability they have found is not easy to exploit, and the exploitation of the use-after-free bugs that can lead to remote code execution involves an uncommon scenario.
BusyBox developers patched all of the vulnerabilities in August with the release of version 1.34.0. Workarounds are also available.
JFrog and Claroty have published a blog post describing their findings. They have shared technical information for one of the vulnerabilities they have found, CVE-2021-42374, which can lead to information leaks and DoS.
Cybercriminals targeting BusyBox devices and abusing BusyBox commands to achieve their goals is not uncommon — examples include DDoS botnets such as Mirai and Bashlite — but attacks typically leverage poor security practices rather than vulnerabilities in BusyBox.