CVE-2019-3844

Description

It was discovered that a systemd service that uses DynamicUser property can get new privileges through the execution of SUID binaries, which would allow a cooperating process to create binaries owned by the service transient group with the setgid bit set. A local attacker may use this flaw to access resources that will be owned by a potentially different service in the future when the GID will be recycled.

Statement

This issue did not affect the versions of systemd as shipped with Red Hat Enterprise Linux 7 as they did not include support for DynamicUser property.

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).

CVSS v3 Score Breakdown

Red HatNVDcve.org
Base Score4.57.8N/A
Attack VectorLocalLocalN/A
Attack ComplexityHighLowN/A
Privileges RequiredLowLowN/A
User InteractionNoneNoneN/A
ScopeUnchangedUnchangedN/A
ConfidentialityLowHighN/A
Integrity ImpactLowHighN/A
Availability ImpactLowHighN/A

Vector

Red Hat: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Understanding the Weakness (CWE)

CWE-268

Access Control

Technical Impact: Gain Privileges or Assume Identity

A user can be given or gain access rights of another user. This can give the user unauthorized access to sensitive information including the access information of another user.

Acknowledgements

Red Hat would like to thank Jann Horn (Google Project Zero) for reporting this issue.

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