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This article introduces what the loophole of Linux Kernel information leakage and privilege promotion refers to, the content is very detailed, interested friends can refer to, I hope it can be helpful to you.

0x00 vulnerability background

On March 31, 2020, 360CERT monitoring found that the Linux kernel privilege enhancement vulnerability demonstrated by ZDI in the Pwn2Own competition has been included by CVE. CVE number: CVE-2020-8835.

The vulnerability was discovered by @ Manfred Paul because the bpf validator did not correctly calculate the register range for certain operations, resulting in incorrect register boundary calculation, which led to out-of-bounds reads and writes.

This vulnerability is introduced in Linux Kernelcommit (581738a681b6).

0x01 risk rating

360CERT assesses the vulnerability

Assessment methods, threat levels, high risk areas are limited.

360CERT recommends that users update Linux Kernel in a timely manner. Do a good job of asset self-check / self-test / prevention to avoid attack.

0x02 affects version

Linux Kernel 5.4

Linux Kernel 5.5

0x03 repair recommendation

Because the lower version of the kernel is not affected or has been repaired in time

It is recommended that users using the latest versions of various distributions (for example, Debain bullseye/sid;Ubuntu 20.04) should be timely.

Update Linux Kernel

The temporary repair plan officially given by Ubuntu

$sudo sysctl kernel.unprivileged_bpf_disabled=1

$echo kernel.unprivileged_bpf_disabled=1 |\

Sudo tee / etc/sysctl.d/90-CVE-2020-8835.conf about Linux Kernel information disclosure and privilege escalation vulnerabilities refer to what is shared here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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