oss-security - Re: Linux Kernel eBPF Improper Input Validation Vulnerability

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Message-ID: <CA+eGCHa7dOhjZQwdA+ONaWQ-JFvn0iK_W0xmgCHgNDvFzROF+Q@mail.gmail.com>
Date: Fri, 14 Jan 2022 16:57:53 +0800
From: tr3e wang <tr3e.wang@...il.com>
To: oss-security@...ts.openwall.com
Subject: Re: Linux Kernel eBPF Improper Input Validation Vulnerability

Hi all,

CVE-2022-23222 has been assigned to this issue.

Thanks,
tr3e

tr3e wang <tr3e.wang@...il.com> 于2022年1月13日周四 16:21写道：

> Hi all,
>
> This vulnerability allows local attackers to escalate privileges on
> affected installations of Linux Kernel. An attacker must first obtain the
> ability to execute low-privileged code on the target system in order to
> exploit this vulnerability.
>
> 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.
> BE AWARE, unprivileged bpf is disabled by default in most distros.
>
> *Affected Version*
>
>     Linux Kernel 5.8 or later
>
> *Root Cause Analysis*
>
> The bpf verifier(kernel/bpf/verifier.c) did not properly restrict several
> *_OR_NULL pointer types which allows these types to do pointer arithmetic.
> This can be leveraged to bypass the verifier check and escalate privilege.
> (see
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/kernel/bpf/verifier.c?h=v5.10.83#n6022
> )
>
> *Exploit Code*
>
> Exploit code will be delayed for 5 days and will be posted at 12:00 UTC,
> Jan 18, 2022
>
> *Mitigations*
>
> set kernel.unprivileged_bpf_disabled to 1
>
> BE AWARE AGAIN, unprivileged bpf is disabled by default in most distros.
>
> *Credits*
>
> tr3e of SecCoder Security Lab
> Best,
> tr3e
>

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