AN1592: Analytic 1592
Modification of Thunderbird message filters file or execution of CLI tools (e.g., formail/procmail) that alter .forward behavior.
Analyst context for executives and security teams
This analytic points to Linux email-handling behavior that can affect how messages are filtered or forwarded, specifically changes to Thunderbird message filters or use of command-line mail processing tools such as formail/procmail that alter .forward behavior. For security leaders, the practical issue is that local mail rules and forwarding behavior can become a blind spot if endpoint, file, and process telemetry do not cover user mail configuration paths and mail-processing utilities.
Executive priority
Prioritize this where Linux endpoints or servers handle business email workflows, regulated communications, or operational notifications. The decision value is not that ATT&CK provides a finished detection here—it does not—but that teams should verify whether mail forwarding and filtering changes are visible, reviewable, and attributable. This supports incident response readiness, audit evidence for message-handling controls, and resilience against unnoticed changes to communications flow.
Technical view
ATT&CK identifies a Linux-focused detection analytic for modification of Thunderbird message filter files or execution of CLI tools such as formail/procmail that alter .forward behavior. Because no official detection logic is provided and no tactic or relationship context is supplied, SOC and detection engineering teams should treat this as a coverage-validation prompt: confirm visibility into relevant file modifications, process executions, user context, and change timing around local mail filtering and forwarding behavior.
Likely telemetry
- Linux endpoint file modification events for Thunderbird message filter files and .forward-related files
- Linux process execution telemetry for mail-processing command-line tools such as formail and procmail
- User, host, timestamp, parent process, and command-line context where available
- File integrity monitoring or EDR records for mail configuration changes
- Change-management or administrative activity records for legitimate mail rule updates
Detection direction
- Validate that Linux telemetry includes both file changes and process execution related to local mail filtering and forwarding behavior.
- Tune review logic to distinguish expected user or administrator mail-rule maintenance from unusual changes by unexpected users, hosts, parent processes, or time windows.
- Because ATT&CK provides no detection text, do not assume existing SIEM or EDR content covers this analytic; test collection and alerting paths directly.
- Watch for blind spots on unmanaged Linux workstations, developer systems, servers without EDR, or user home directories excluded from file monitoring.
- Correlate with local environment knowledge, because the object provides no tactics, relationships, or adversary context to define severity by itself.
Mitigation priorities
- Inventory Linux systems where Thunderbird, formail, procmail, or .forward-based mail behavior is relevant.
- Ensure endpoint logging, file monitoring, or EDR coverage includes mail configuration files and relevant command execution where operationally appropriate.
- Restrict and review who can modify mail forwarding and filtering configurations on systems where message integrity or availability matters.
- Add documented administrative change procedures for legitimate mail-rule updates to reduce false positives and support audit evidence.
- Use incident response playbooks to include review of local mail filters and forwarding behavior when investigating suspicious communication handling.
Analyst notes and limits
This object is a detection analytic, not a full ATT&CK technique, and it has no supplied relationship context. The strongest use is as a defensive checklist item for Linux mail configuration visibility and change accountability. Local baselining is important because legitimate mail filtering and forwarding changes may be common in some environments and rare in others.
The official object supplies only a short description, Linux platform scope, and an external reference. It does not provide official detection logic, tactics, related techniques, adversary use, impact, data sources, or mitigations. Any severity, detection content, or response workflow must be validated against the local environment.
Analytic 1592
Modification of Thunderbird message filters file or execution of CLI tools (e.g., formail/procmail) that alter .forward behavior.
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
All related ATT&CK context
No relationships are available in the current normalized data for this object.
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates .
Imported snapshots across ATT&CK releases (1)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 19.1 | 1.0 | Current bundle | ae58471d0a4a… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
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[1]
mitre-attack AN1592Open source URL
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