CVE-2018-10923
Description
It was found that the "mknod" call derived from mknod(2) can create files pointing to devices on a glusterfs server node. An authenticated attacker could use this to create an arbitrary device and read data from any device attached to the glusterfs server node.
Statement
This issue did not affect Red Hat Enterprise Linux 6 and 7 as the flaw is present in glusterfs-server, which is not shipped there.
This flaw affects glusterfs versions included in Red Hat Virtualization 4 Hypervisor. However, in recommended configurations, the vulnerability is only exposed to hypervisor administrators and can not be exploited from virtual machines or other hosts on the network. For Red Hat Virtualization, Product Security has rated this flaw as Moderate. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.
Mitigation
To limit exposure of gluster server nodes :
1. gluster server should be on LAN and not reachable from public networks.
2. Use gluster auth.allow and auth.reject.
3. Use TLS certificates to authenticate gluster clients.
caveat: This does not protect from attacks by authenticated gluster clients.
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 | 7.6 | 8.1 | 7.6 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | Low | High | Low |
| Availability Impact | Low | None | Low |
Vector
Red Hat: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
Acknowledgements
Red Hat would like to thank Michael Hanselmann (hansmi.ch) for reporting this issue.
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