CVE-2020-25284
Description
A flaw was found in the capabilities check of the rados block device functionality in the Linux kernel. Incorrect capability checks could alllow a local user with root priviledges (but no capabilities) to add or remove Rados Block Devices from the system.
Mitigation
As the rbd module can be loaded by a priviledged user or process, its use can be disabled by preventing the module from loading with the following instructions:
# echo "install rbd /bin/true" >> /etc/modprobe.d/disable-rdb.conf
The system will need to be restarted if the modules isloaded. In most circumstances, the rbd kernel modules will be unable to be unloaded while in use.
If the system requires this module to work correctly, (Such as a CEPH node) this mitigation may not be suitable.
If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services.
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 | 4.1 | 4.1 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | High | High | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
Red Hat CVSS v3 Score Explanation
The attacker must already have a reduced 'root' like access with dropped capabilities to take advantage of this flaw. This would not be PR: None, PR:L (not a standard user) .. so the only option left is PR:H.
AC:H, as I do not see this attack vector open on standard RHEL installs.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data; Read Files or Directories
An attacker may be able to read sensitive information from the associated resource, such as credentials or configuration information stored in a file.
Access Control
Technical Impact: Gain Privileges or Assume Identity
An attacker may be able to modify critical properties of the associated resource to gain privileges, such as replacing a world-writable executable with a Trojan horse.
Integrity,Other
Technical Impact: Modify Application Data; Other
An attacker may be able to destroy or corrupt critical data in the associated resource, such as deletion of records from a database.
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