CVE-2019-2054
Description
A flaw was found in the Linux kernel's seccomp implementation which contained a method to bypass seccomp syscall filtering policies that allowed ptrace. This could allow an attacker with code execution privileges within the sandbox to use ptrace to execute systemcalls that would be filtered by the policy.
Statement
Red Hat has considers this CVE as with a 'Moderate' severity due specific conditions required to bypass seccomp. The attacker must have code execution privileges within the seccomp-restricted sandbox and the ptrace syscall should be allowed to be ran, from this perspective this CVE is understood more as a sandbox hardening issue than a important security flaw that'd impact system's core integrity. The outcomes of a possible exploitation is limited to process that are already running within an restricted environment.
Additionally this behavior is clearly defined in the seccomp manual page.
After reviewing this CVE, Red Hat Enterprise Linux 8 is marked as Not Affected. This decision is based in the fact of the Linux Kernel version shipped already contains the necessary patches which changes the execution order between ptrace and seccomp calls, making seccomp validates and eventual system call changes executed by the ptrace functionality.
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 | 8.4 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality,Access Control,Availability,Other
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity; Varies by Context
Attackers can bypass the security decision to access whatever is being protected. The consequences will depend on the associated functionality, but they can range from granting additional privileges to untrusted users to bypassing important security checks. Ultimately, this weakness may lead to exposure or modification of sensitive data, system crash, or execution of arbitrary code.
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