Security Experts:

Many Vulnerabilities Found in Linux USB Subsystem

A Google researcher has found a significant number of vulnerabilities in the Linux kernel USB subsystem using the Syzkaller fuzzer.

The fuzzing tool developed by Google helped Andrey Konovalov find tens of bugs, including 22 security flaws that have been assigned CVE identifiers. In an advisory published this week, the expert detailed 14 of the vulnerabilities he discovered.

The vulnerabilities have been described as use-after-free, general protection fault, out-of-bounds read, and NULL pointer dereference issues that can be exploited to cause a denial-of-service (DoS) condition. The expert said some of the flaws might have a different impact as well, which typically means they could allow arbitrary code execution.

Konovalov pointed out that an attacker needs to have physical access to the targeted system and connect a malicious USB device in order to exploit the vulnerabilities. Others suggested that an attacker who has remote access to a machine may be able to update the firmware on connected USB drives to plant exploits for these flaws and create malicious devices.

Fixes for many of the vulnerabilities found by Konovalov are included in Linux kernel versions 4.13.4 and later, but many of the issues remain unpatched. On the other hand, Linux distributions don’t seem too concerned about these security holes and assigned them low severity ratings.

These are not the only flaws discovered by the Google researcher in the Linux kernel. Back in February, he reported finding a locally exploitable code execution weakness that had been present in the kernel for more than 11 years. This double-free vulnerability (CVE-2017-6074) was also identified using the Syzkaller fuzzer.

In May, he disclosed the details of a privilege escalation bug that could be exploited via packet sockets.

An analysis of more than 600 CVEs conducted last year showed that the average lifetime of a Linux kernel vulnerability is 5 years.

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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.