M365 Exchange Inbox Rule with Obfuscated Name
Identifies when a Microsoft Exchange inbox rule is created or modified with a name composed only of special characters. Adversaries may use obfuscated inbox rule names to evade detection, hide malicious forwarding or…
Description
Identifies when a Microsoft Exchange inbox rule is created or modified with a name composed only of special characters. Adversaries may use obfuscated inbox rule names to evade detection, hide malicious forwarding or deletion rules, or blend in with benign audit noise. The rule name is parsed from "o365.audit.ObjectId", which encodes the mailbox identity and rule name separated by a backslash.
Detection logic
Its licence does not clear it for publishing here
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Detection requirements
- Platform
- ESXiLinuxmacOSOffice SuiteWindows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
Known benign triggers
- Rare legitimate automation or third-party tools may create inbox rules with non-alphanumeric names. Validate against known messaging workflows and approved admin scripts before escalating.
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 |
|---|---|
| www.microsoft.com/en-us/security/blog/2026/04/06/ai-enabled-device-code-phishing-campaign-april-2026/ | 2 |
From the source
- At source
- Open at source
- Upstream identifier
- 1c3d9346-4591-4894-935c-dad2824850f2
- Tagged by the source as
- Data Source: Microsoft 365Data Source: Microsoft 365 Audit LogsDomain: CloudDomain: EmailDomain: SaaSNoise: UnknownPerformance: NormalPlatform: Microsoft 365Resources: Investigation GuideRule Type: ES|QLService: Microsoft Exchange OnlineTactic: Defense EvasionUse Case: Threat Detection
Licence
- Published under
- Elastic License 2.0Read the licence
- Attribution
- Required
Authorship
- Written by
- Published
- Sep 20, 2026
- Version
- 3