CVE-2017-18078

systemd (systemd-tmpfiles) < 236 - 'fs.protected_hardlinks=0' Local Privilege Escalation

Severity Score

7.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

systemd-tmpfiles en systemd en versiones anteriores a la 237 intenta soportar cambios de propiedad/permisos en archivos con vínculos permanentes incluso aunque el sysctl fs.protected_hardlinks esté apagado. Esto permite que usuarios locales omitan las restricciones de acceso planeadas mediante vectores relacionados con un enlace permanente a un archivo para el que el usuario no tiene acceso de escritura, tal y como demuestra el cambio de propiedad del archivo /etc/passwd.

systemd (systemd-tmpfiles) versions prior to 236 suffer from an fs.protected_hardlinks=0 local privilege escalation vulnerability.

*Credits: N/A

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2018-01-28 CVE Reserved
2018-01-29 CVE Published
2023-05-08 EPSS Updated
2024-08-05 CVE Updated
2024-08-05 First Exploit
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-59: Improper Link Resolution Before File Access ('Link Following')

CAPEC

References (9)

URL	Tag	Source
https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E	Mailing List
https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E	Mailing List
https://lists.debian.org/debian-lts-announce/2019/04/msg00022.html	Mailing List
https://www.openwall.com/lists/oss-security/2018/01/29/4	Mailing List

URL	Date	SRC
https://www.exploit-db.com/exploits/43935	2024-08-05
http://packetstormsecurity.com/files/146184/systemd-Local-Privilege-Escalation.html	2024-08-05
http://www.openwall.com/lists/oss-security/2018/01/29/3	2024-08-05
https://github.com/systemd/systemd/issues/7736	2024-08-05

URL	Date	SRC

URL	Date	SRC
http://lists.opensuse.org/opensuse-updates/2018-02/msg00109.html	2023-11-07

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Systemd Project Search vendor "Systemd Project"		Systemd Search vendor "Systemd Project" for product "Systemd"				< 237 Search vendor "Systemd Project" for product "Systemd" and version " < 237"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				8.0 Search vendor "Debian" for product "Debian Linux" and version "8.0"		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				42.3 Search vendor "Opensuse" for product "Leap" and version "42.3"		-		Affected