CVE-2020-15679

An OAuth session fixation vulnerability existed in the VPN login flow, where an attacker could craft a custom login URL, convince a VPN user to login via that URL, and obtain authenticated access as that user. This issue is limited to cases where attacker and victim are sharing the same source IP and could allow the ability to view session states and disconnect VPN sessions. This vulnerability affects Mozilla VPN iOS 1.0.7 < (929), Mozilla VPN Windows < 1.2.2, and Mozilla VPN Android 1.1.0 < (1360).

Weakness

Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.

Affected Software

Extended Description

Such a scenario is commonly observed when:

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/196.html
• https://cwe.mitre.org/data/definitions/21.html
• https://cwe.mitre.org/data/definitions/31.html
• https://cwe.mitre.org/data/definitions/39.html
• https://cwe.mitre.org/data/definitions/59.html
• https://cwe.mitre.org/data/definitions/60.html
• https://cwe.mitre.org/data/definitions/61.html

References

• https://github.com/mozilla-mobile/guardian-vpn-android/commit/981c840276ef3aee98cf5d42993d484ee99b28d9
• https://github.com/mozilla-mobile/guardian-vpn-ios/commit/4309f5c9bd2c15cdfd39ac173665fad3f2598b54
• https://github.com/mozilla-services/guardian-vpn-windows/commit/ac6f562973a83f6758cd7ab7aa313e863047d41b
• https://www.mozilla.org/security/advisories/mfsa2020-48/