Message forwarding abuse is the practice of relaying a bot’s stored messages into another account or endpoint for monitoring or interception. In an investigation, it can expose attacker communications and stolen data, but it also requires careful handling to preserve evidence and avoid altering the original message flow.
How message forwarding abuse works
Message forwarding abuse is not a forwarding feature in the ordinary product sense, it is a collection and interception technique. The operator copies a bot’s stored messages into another account, mailbox, queue, or endpoint so the content can be monitored, replayed, or quietly siphoned off.
That distinction matters because the forwarded copy can preserve attacker chatter, tasking, exfiltrated data, and operational detail that would otherwise be buried inside the original channel. In investigations, the value is not just visibility, but the ability to understand how the bot was used and where the message stream actually terminated.
Why it matters in investigations and operations
Forwarded bot messages can reveal command content, staging instructions, stolen tokens, customer data, or follow-on targets. That makes the technique useful for incident response, but it also means the forwarding path itself becomes sensitive evidence and should be handled as such.
When a forwarding workflow is introduced, the defender is effectively creating a second trust boundary around the same content. If the copy destination is broader than the original scope, or if the destination account is weakly controlled, the forwarding path can become a new place where sensitive material is exposed.
Common abuse patterns and failure points
Message forwarding abuse often appears alongside compromised access, overly broad mailbox rules, automation abuse, or third-party integrations that can read and relay content at scale. A bot with stored messages is especially useful to an attacker because it can preserve a trail of communications and secrets even after the initial compromise is discovered.
- GitHub Dependabot Breach, for a concrete example of token theft leading to malicious reuse of stored trust material.
- Microsoft OAuth Breach, for how abused application trust can support persistent access and message or data interception.
- Snowflake breach, for cloud credential abuse that enabled broad access to stored information.
The main failure point is assuming that forwarded copies are operationally harmless because the original system still exists. In practice, the copy is often where visibility, retention, and unauthorized access converge.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK address the attack and risk surface, while CIS Controls v8 and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1114 — Email Collection | Message forwarding abuse relays stored messages to another endpoint for collection and interception. |
| T1078 — Valid Accounts | Forwarding abuse often relies on abused legitimate access to read and relay stored messages. | |
| Recommendation — Map forwarding activity to T1114 and investigate unauthorized collection paths and message duplication. Hunt for legitimate accounts used to create or exploit unauthorized message relays. | ||
| CIS Controls v8 | 6 — Access Control Management | Forwarding paths expand access to message content and need explicit authorization and review. |
| 8 — Audit Log Management | Detection depends on logging forwarding-rule creation, relay destinations, and message access. | |
| Recommendation — Restrict who can configure forwarding and review message-access paths regularly. Log forwarding changes and alert on new relay destinations or unusual message export patterns. | ||
| NIST CSF 2.0 | PR.AA — Identity Management, Authentication, and Access Control | Forwarding abuse changes who can access stored messages and where those messages flow. |
| DE.CM — Continuous Monitoring | Suspicious forwarding destinations and duplicate message flow require continuous detection. | |
| Recommendation — Apply access controls to message-relay capabilities and limit who can create forwarding paths. Monitor for unauthorized forwarding rules, destination changes, and abnormal message flow. | ||
Practitioner Guidance
What to watch for: Treat unexpected forwarding destinations, new relay accounts, and unexplained message duplication as high-signal events. The key question is whether the forwarding path is approved, narrowly scoped, and auditable, or whether it has become a shadow collection channel.
Governance implication: Decide who owns the forwarding relationship, who can authorize it, and how long copied messages may persist. The forwarding path should be reviewed with the same seriousness as any other mechanism that expands message access or changes evidence handling.
