Linux Kernel Extended BPF Verifier Information Disclosure Vulnerability

A vulnerability in the extended Berkeley Packet Filter (eBPF) verifier of the Linux Kernel could allow a local attacker to access sensitive information on a targeted system.

The vulnerability is due to improper handling of states_equal comparisons between the pointer data type and the UNKNOWN_VALUE data type by the affected software. An attacker could exploit this vulnerability to trigger a pointer leak on a targeted system. A successful exploit could allow the attacker to access sensitive address information, which could be used to conduct further attacks.

Kernel.org has confirmed the vulnerability and released a software patch.

Technical Information
The vulnerability exist in the kernel/bpf/verifier.c source code of the affected software and is due to improper handling of states_equal comparisons between the pointer data type and the UNKNOWN_VALUE data type. A successful exploit of this vulnerability could trigger a pointer leak that could allow the attacker to access sensitive address information on a targeted system.
Analysis
To exploit this vulnerability, an attacker must have local access to the targeted system. This access requirement may reduce the likelihood of a successful exxploit.
Safeguards

Administrators are advised to apply the appropriate updates.

Administrators are advised to allow only trusted users to access local systems.

Administrators are advised to monitor affected systems.

Vendor Announcements
Kernel.org has released a git commit at the following link: CVE-2017-17864
Fixed Software
Kernel.org has released a patch at the following link: bpf: don’t prune branches when a scalar is replaced with a pointer




Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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