huntrule

Microsoft Exchange: Mailbox export to UNC path or .aspx filename with possible role assignment

Flags Exchange mailbox export commands targeting UNC paths with .aspx or granting the Mailbox Import Export role.

FreeReviewedSigma · Critical · v2
Product
windows
Service
msexchange-management
Author
Florian Roth (Nextron Systems), Rich Warren, Christian Burkard (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2021-08-09
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Persistence

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags successful use of Exchange management commands that export a mailbox to a network share using a FilePath ending in .aspx, which could be used to place executable web content. It also alerts when the command sequence assigns the "Mailbox Import Export" management role to a user, enabling mailbox export/import capabilities. The detection relies on telemetry from the msexchange-management service capturing command content, including New-MailboxExportRequest parameters and New-ManagementRoleAssignment arguments.

Reporting behind it

Related detections9 linkedT1505.003 — drag to rearrange
Possible Ivanti Connect Secure Webshell Access
Malicious Shell Spawned by SharePoint Worker Process w3wp
Suspicious SD-WAN Compromise JSP Webshell Access
Malicious AquaShell Webshell Access on Cisco Secure Email Gateway by UAT-9686
Malicious IIS Worker Process Spawning Command Shell Reconnaissance
Malicious StyleSmuggler (CVE-2026-75650) Web Shell Dropped In Magento Product Image Cache (via file_event)
Suspicious Web Shell File Written to IIS wwwroot Directory
Possible Citrix ShareFile Unauthenticated Upload Path Traversal Webshell (CVE-2023-24489) (via webserver)
Possible Unauthenticated Admin Creation in Dynamicweb CVE-2022-25369
Microsoft Exchange: Mailbox export to UNC path or .aspx filename with possible role assignment
Pivot detection · T1505.003 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

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