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TunnelVision - decloaking VPNs using DHCP

Low
M0dEx published GHSA-hqmp-g7ph-x543 May 6, 2024

Package

cargo quincy (Rust)

Affected versions

*

Patched versions

None

Description

A new decloaking technique for nearly all VPN implementations has been found, which allows attackers to inject entries into the routing tables of unsuspecting victims using DHCP option 121. This allows attackers to redirect traffic, which is supposed to be sent encrypted over the VPN, through the physical interface handling DHCP for the network the victim's computer is connected to, effectively bypassing any and all confidentiality provided by the VPN.

Impact

All users are potentially affected, as this attack vector can be used against any VPN implementation without mitigations in place.

Patches

Currently, there are no existing mitigations employed by Quincy.

Workarounds

Disabling DHCP option 121 in the DHCP client is a potential workaround, as it prevents this kind of attack.

References

https://www.leviathansecurity.com/blog/tunnelvision

Severity

Low

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
Adjacent
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

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:A/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVE ID

CVE-2024-3661

Weaknesses

No CWEs