CVE-2018-1088
Description
A privilege escalation flaw was found in gluster snapshot scheduler. Any gluster client allowed to mount gluster volumes could also mount shared gluster storage volume and escalate privileges by scheduling malicious cronjob via symlink.
Statement
This vulnerability affects gluster servers that have, or have previously had, Gluster volume snapshot scheduling enabled from the CLI. Red Hat Enterprise Virtualization supports volume snapshot scheduling from the Web UI, which uses a distinct mechanism that is not subject to this vulnerability. VM snapshots are not impacted by this flaw. For more information, please see the Vulnerability Article linked under External References.
This issue did not affect the versions of glusterfs as shipped with Red Hat Enterprise Linux 6, and 7 because only gluster client is shipped in these products. CVE-2018-1088 affects glusterfs-server package as shipped with Red Hat Gluster Storage 3.
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 between gluster server nodes and clients.
Caveat: This would only mitigate attacks from unauthorized malicious clients. gluster clients allowed by auth.allow or having signed TLS client certificates would still be able to trigger this attack.
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 | 8.3 | 8.1 | N/A |
| Attack Vector | Adjacent Network | Network | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | 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:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity
A user can access restricted functionality and/or sensitive information that may include administrative functionality and user accounts.
Acknowledgements
This issue was discovered by John Strunk (Red Hat).
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