### [CVE-2017-18078](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-18078)
![](https://img.shields.io/static/v1?label=Product&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=brighgreen)

### Description

systemd-tmpfiles in systemd before 237 attempts to support ownership/permission changes on hardlinked files even if the fs.protected_hardlinks sysctl is turned off, which allows local users to bypass intended access restrictions via vectors involving a hard link to a file for which the user lacks write access, as demonstrated by changing the ownership of the /etc/passwd file.

### POC

#### Reference
- http://packetstormsecurity.com/files/146184/systemd-Local-Privilege-Escalation.html
- http://www.openwall.com/lists/oss-security/2018/01/29/3
- https://www.exploit-db.com/exploits/43935/

#### Github
- https://github.com/blackberry/UBCIS
- https://github.com/flyrev/security-scan-ci-presentation