CVE-2018-6557 : The MOTD update script in the base-files package in Ubuntu 18.04 LTS before 10.1

The MOTD update script in the base-files package in Ubuntu 18.04 LTS before 10.1ubuntu2.2, and Ubuntu 18.10 before 10.1ubuntu6 incorrectly handled temporary files. A local attacker could use this issue to cause a denial of service, or possibly escalate privileges if kernel symlink restrictions were disabled.

Published 2018-08-21 16:29:01

Updated 2023-01-18 21:22:39

Source Canonical Ltd.

View at NVD, CVE.org

Vulnerability category: Denial of service

Products affected by CVE-2018-6557

Canonical » Ubuntu Linux » Version: 18.04 LTS Edition
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
Matching versions
Canonical » Ubuntu Linux » Version: 18.10
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
Matching versions
Base-files Project » Base-files » Version: 10.1ubuntu2.2
cpe:2.3:a:base-files_project:base-files:10.1ubuntu2.2:*:*:*:*:*:*:*
Matching versions

Threat overview for CVE-2018-6557

Top countries where our scanners detected CVE-2018-6557

Top open port discovered on systems with this issue 80

IPs affected by CVE-2018-6557 7,042

Threat actors abusing to this issue? Yes

Find out if you^* are affected by CVE-2018-6557!

^*Directly or indirectly through your vendors, service providers and 3rd parties. Powered by attack surface intelligence from SecurityScorecard.

Exploit prediction scoring system (EPSS) score for CVE-2018-6557

EPSS FAQ

0.12%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 28 %

Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2018-6557

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
4.4	MEDIUM	AV:L/AC:M/Au:N/C:P/I:P/A:P	3.4	6.4	NIST
Access Vector: Local Access Complexity: Medium Authentication: None Confidentiality Impact: Partial Integrity Impact: Partial Availability Impact: Partial
7.0	HIGH	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H	1.0	5.9	NIST
Attack Vector: Local Attack Complexity: High Privileges Required: Low User Interaction: None Scope: Unchanged Confidentiality: High Integrity: High Availability: High

CWE ids for CVE-2018-6557

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

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Assigned by: nvd@nist.gov (Primary)

References for CVE-2018-6557

http://www.securitytracker.com/id/1041530

Debian Linux MOTD Update Script Unsafe Temporary File Usage Lets Local Users Deny Service and Gain Elevated Privileges - SecurityTracker
Broken Link;Third Party Advisory;VDB Entry
http://www.securityfocus.com/bid/105148

Debian Linux MOTD Update Script CVE-2018-6557 Insecure Temporary File Handling Vulnerability
Third Party Advisory;VDB Entry
https://usn.ubuntu.com/3748-1/

USN-3748-1: base-files vulnerability | Ubuntu security notices
Vendor Advisory