CVE-2021-3864 PoC — Linux kernel 访问控制错误漏洞

Title:Linux kernel 访问控制错误漏洞 (CVE-2021-3864)
Description:A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants. The prerequisite is a SUID binary that sets real UID equal to effective UID, and real GID equal to effective GID. The descendant will then have a dumpable value set to 1. As a result, if the descendant process crashes and core_pattern is set to a relative value, its core dump is stored in the current directory with uid:gid permissions. An unprivileged local user with eligible root SUID binary could use this flaw to place core dumps into root-owned directories, potentially resulting in escalation of privileges.

Test for cve-2021-3864

Test for [CVE-2021-3864](https://access.redhat.com/security/cve/CVE-2021-3864).

How to run
----------

* create a user
* `echo <username> ALL= path/to/gen-core >> /etc/sudoers`
* `sysctl kernel.core_pattern=core`
* ./cve-2021-3864
* It should generate a core file in /etc/logrotate.d

 [4.0K]  /data/pocs/c52cb8fe9293585ddfb1c5bcda5cf503da99683d
├── [1.3K]  cve-2021-3864.c
├── [  94]  gen-core.c
├── [ 272]  Makefile
└── [ 285]  README.md

0 directories, 4 files