CVE-2023-3899
Description
A vulnerability was found in subscription-manager that allows local privilege escalation due to inadequate authorization. The D-Bus interface com.redhat.RHSM1 exposes a significant number of methods to all users that could change the state of the registration. By using the com.redhat.RHSM1.Config.SetAll() method, a low-privileged local user could tamper with the state of the registration, by unregistering the system or by changing the current entitlements. This flaw allows an attacker to set arbitrary configuration directives for /etc/rhsm/rhsm.conf, which can be abused to cause a local privilege escalation to an unconfined root.
Statement
The vulnerable method SetAll() allows the non-root user to Local Privilege Escalation. The vulnerable method is present since subscription-manager-1.26.15-1. Currently, RHEL-8.2. and above contains the vulnerable code.
However, before the SetAll() was introduced, the worst thing that could happen is to unregister the system and cut off system from updates. No privilege escalation is possible in RHEL-7.9, and RHEL-8.1 as those streams ships subscription-manager-1.25.17.1-1 and prior. Making it Moderate issue for those streams.
So, the vulnerability has always been there, the SetAll() method that introduced with later version in subscription-manager turned it to a to Local Privilege Escalation.
Mitigation
A workaround is to mask rhsm.service using:
systemctl mask rhsm.service
When the rhsm.service is masked, then no D-Bus call cannot trigger the service and all D-Bus calls will be terminated with error: "Call failed: Could not activate remote peer." But then all applications using D-Bus API will not work until you unmask the service using: "systemctl unmask rhsm.service"
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 Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | 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:3.1/AV:L/AC:L/PR:L/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
Technical Impact: Read Application Data; Read Files or Directories
An attacker could read sensitive data, either by reading the data directly from a data store that is not properly restricted, or by accessing insufficiently-protected, privileged functionality to read the data.
Integrity
Technical Impact: Modify Application Data; Modify Files or Directories
An attacker could modify sensitive data, either by writing the data directly to a data store that is not properly restricted, or by accessing insufficiently-protected, privileged functionality to write the data.
Access Control
Technical Impact: Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands
When access control checks are not applied consistently - or not at all - an attacker could gain privileges and execute unauthorized code or commands by modifying or reading critical data directly, or by accessing insufficiently-protected, privileged functionality.
Acknowledgements
This issue was discovered by Thibault Guittet (Senior Product Security Engineer, Red Hat).
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