Security Experts:

Patch Released for Linux Kernel Vulnerability Disclosed at Hacking Contest

A patch has been released for a Linux kernel vulnerability that a researcher used at the recent Pwn2Own 2020 hacking competition to escalate privileges to root on Ubuntu Desktop.

Researchers who took part this year in the Zero Day Initiative’s Pwn2Own competition earned a total of $270,000 for exploiting vulnerabilities in Windows, Ubuntu Desktop, macOS, Safari, Oracle VirtualBox, and Adobe Reader.

Researcher Manfred Paul of the RedRocket CTF team earned $30,000 for a local privilege escalation exploit targeting Ubuntu Desktop. He leveraged an improper input validation bug in the Linux kernel to escalate privileges to root.

“The specific flaw exists within the handling of eBPF programs. The issue results from the lack of proper validation of user-supplied eBPF programs prior to executing them. An attacker can leverage this vulnerability to escalate privileges and execute code in the context of the kernel,” ZDI explained in an advisory published on Tuesday.

The vulnerability has been classified as high severity and it has been assigned the CVE identifier CVE-2020-8835. Linux kernel developers have patched the bug and Ubuntu has released updates and mitigations to address the vulnerability.

Red Hat says Enterprise Linux 5, 6, 7 and 8 and Red Hat Enterprise MRG 2 are not affected as the kernel version they use did not backport the commit that introduced the flaw. Fedora, on the other hand, is impacted. Red Hat also pointed out that exploitation of the weakness could cause the kernel to crash, resulting in a DoS condition.

Debian claims only Bullseye, its current testing distribution, is affected by the vulnerability.

Ubuntu security engineer Steve Beattie has made available some technical details about the vulnerability.

Related: Serious Vulnerabilities in Linux Kernel Allow Remote DoS Attacks

Related: Linux Kernel Privilege Escalation Vulnerability Found in RDS Over TCP

Related: Linux Kernel Vulnerability Affects Red Hat, CentOS, Debian

view counter
Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.