CVE-2019-12522
Description
A flaw was found in squid. 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. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Statement
This issue is not a big problem on its own, as it requires another remote code execution vulnerability or that a local user has the privileges to modify the squid processes to be exploited. Thus, it is actually closer to a security enhancement than a vulnerability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.5 | 4.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | Low | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | Low | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
NVD: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
Red Hat CVSS v3 Score Explanation
This issue is not a big problem on its own, as it requires another remote code execution vulnerability or that a local user has the privileges to modify the squid processes to be exploited. Thus, it is actually closer to a security enhancement than a vulnerability. Unfortunately, such a case is hard to reflect accurately within the CVSS scoring system. As a compromise, AV:L, AC:H, and PR:L have been used to reflect that an attacker needs a method to gain control of the squid processes. Although one could argue that C:H, I:H, and A:H should be used, this has been set to C:L, I:L, and A:L, so that the score is closer to the perceived risk, given the special circumstances.
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity
A user can access restricted functionality and/or sensitive information that may include administrative functionality and user accounts.
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