An issue was discovered in Squid through 4.7. When Squid is run as root, it spawns its child processes as a lesser user, by default the user nobody. This is done via the leave_suid call. leave_suid leaves the Saved UID as 0. This makes it trivial for an attacker who has compromised the child process to escalate their privileges back to root.
Weakness
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Squid | Squid-cache | * | 4.7 (including) |
| Squid | Ubuntu | eoan | * |
| Squid | Ubuntu | focal | * |
| Squid | Ubuntu | groovy | * |
| Squid | Ubuntu | hirsute | * |
| Squid | Ubuntu | impish | * |
| Squid | Ubuntu | kinetic | * |
| Squid | Ubuntu | lunar | * |
| Squid | Ubuntu | mantic | * |
| Squid | Ubuntu | oracular | * |
| Squid | Ubuntu | plucky | * |
| Squid | Ubuntu | trusty | * |
| Squid | Ubuntu | upstream | * |
| Squid3 | Ubuntu | bionic | * |
| Squid3 | Ubuntu | precise/esm | * |
| Squid3 | Ubuntu | trusty | * |
| Squid3 | Ubuntu | upstream | * |
| Squid3 | Ubuntu | xenial | * |
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/122.html
- https://cwe.mitre.org/data/definitions/233.html
- https://cwe.mitre.org/data/definitions/58.html