Quantum Secular Labs / Blog / Advisories
CVE-2018-8712: Webmin: Improper Limitation of a Pathname to a Restricted Directory
CVE-2018-8712 is rated critical with a CVSS v3.0 base score of 9.8 and affects Webmin. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.
Vulnerability description
An issue was discovered in Webmin 1.840 and 1.880 when the default Yes setting of "Can view any file as a log file" is enabled. As a result of weak default configuration settings, limited users have full access rights to the underlying Unix system files, allowing the user to read sensitive data from the local system (using Local File Include) such as the '/etc/shadow' file via a "GET /syslog/save_log.cgi?view=1&file=/etc/shadow" request.
Severity breakdown
CVSS v3.0 9.8: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
- Attack complexity: Low. No special conditions; the attack can be repeated reliably.
- Privileges required: None. No account or prior access is needed.
- User interaction: None. No action from any user is needed.
- Scope: Unchanged. Impact stays within the vulnerable component.
- Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
- Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
- Availability impact: High. Total loss of availability; the component can be shut down.
Underlying weakness
CWE-22: Improper Limitation of a Pathname to a Restricted Directory
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
Affected products
- Webmin: 1.840; 1.880