Malicious SSH authorized_keys Modification for Persistence on Appliance

ATT&CK techniques

Persistence → Priv Esc

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1098.004SSH Authorized Keys
Priv Esc
- T1098.004SSH Authorized Keys
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects command line activity that writes to an SSH authorized_keys file, the key-based persistence mechanism observed after exploitation of the Cisco SD-WAN CVE-2026-20127 vulnerability. Adding an attacker key to authorized_keys grants durable root access and enables lateral movement between appliances. Editing authorized_keys through a shell command outside of provisioning is suspicious on an appliance.

Reporting behind it

Related detections9 linkedT1098.004 — drag to rearrange

Malicious vmanage-admin Public Key Authentication in SSH Auth Log

Suspicious SSH authorized_keys Modification for Persistence

Malicious Immutable Attribute Set on SSH Authorized Keys via chattr on Linux

Suspicious SSH authorized_keys Persistence Modification (via process_creation)

Malicious EtherRAT SSH authorized_keys Backdoor Injection via Shell (via process_creation)

Malicious UNC4841 SSH Backdoor Persistence via Non-Standard Port and AllowUsers Restriction (via process_creation)

Malicious SSH authorized_keys Modification Following Web Server Compromise (via process_creation)

Suspicious Modification of SSH Authorized Keys on SD-WAN Appliance by UAT-8616

Malicious Immutable Flag on SSH authorized_keys via chattr

Malicious SSH authorized_keys Modification for Persistence on Appliance

Pivot detection · T1098.004 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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