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cloudflared's Installer has Local Privilege Escalation Vulnerability

High severity GitHub Reviewed Published Mar 21, 2023 in cloudflare/cloudflared

Package

gomod github.com/cloudflare/cloudflared (Go)

Affected versions

< 0.0.0-20230313153246-f686da832f85

Patched versions

0.0.0-20230313153246-f686da832f85

Description

Impact

A vulnerability has been discovered in cloudflared's installer (<= 2023.3.0) for Windows 32-bits devices that allows a local attacker with no administrative permissions to escalate their privileges on the affected device. This vulnerability exists because the MSI installer used by cloudflared relied on a world-writable directory.

An attacker with local access to the device (without Administrator rights) can use symbolic links to trick the MSI installer into deleting files in locations that the attacker would otherwise have no access to. By creating a symlink from the world-writable directory to the target file, the attacker can manipulate the MSI installer's repair functionality to delete the target file during the repair process.

Exploitation of this vulnerability could allow an attacker to delete important system files or replace them with malicious files, potentially leading to the affected device being compromised.

The cloudflared client itself is not affected by this vulnerability, only the installer for 32-bit Windows devices.

Patches

A new installer was released as part of version 2023.3.1, corresponding to pseudoversion 0.0.0-20230313153246-f686da832f85 on pkg.go.dev. Users are encouraged to remove old installers from their systems.

References

Cloudflared Releases

References

@ncabetecf ncabetecf published to cloudflare/cloudflared Mar 21, 2023
Published by the National Vulnerability Database Mar 21, 2023
Published to the GitHub Advisory Database Mar 21, 2023
Reviewed Mar 21, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:H

EPSS score

0.042%
(5th percentile)

Weaknesses

CVE ID

CVE-2023-1314

GHSA ID

GHSA-7mjv-x3jf-545x
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