First Time Seen NFS AUTH_SYS Root UID Access
Identifies the first source and destination IP pair observed in a five-day history window where an NFS client asserts AUTH_SYS (RPC UNIX) credentials with UID 0 (root). NFSv3 and NFSv4 clients can claim arbitrary…
Description
Identifies the first source and destination IP pair observed in a five-day history window where an NFS client asserts AUTH_SYS (RPC UNIX) credentials with UID 0 (root). NFSv3 and NFSv4 clients can claim arbitrary UIDs through AUTH_SYS, and weak export controls may honor root-equivalent access from unexpected hosts. This is a common precursor to unauthorized mounts, sensitive file reads, and remote encryption of exported shares.
Detection logic
Its licence does not clear it for publishing here
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Detection requirements
- Platform
- IaaSLinuxmacOSOffice SuiteSaaSWindows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
- Log source category
- event_index
Known benign triggers
- Legitimate NFS root squashing misconfiguration, administrative automation, or backup appliances may present UID 0 from known infrastructure. Confirm the source IP against approved NFS client inventories before closing.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| attack.mitre.org/techniques/T1039/ | 2 |
| attack.mitre.org/techniques/T1213/ | 2from 2 sources |
From the source
- At source
- Open at source
- Upstream identifier
- 35ef761a-7136-4cb9-a32d-4e7abddb3bac
- Tagged by the source as
- Data Source: Network Packet CaptureDomain: NetworkNoise: MediumPerformance: FastResources: Investigation GuideRule Type: New TermsTactic: CollectionUse Case: Network Security MonitoringUse Case: Threat Detection
Licence
- Published under
- Elastic License 2.0Read the licence
- Attribution
- Required
Authorship
- Written by
- Published
- Sep 20, 2026
- Version
- 3