Relay Pattern Analysis is the study of traffic or identity flows that pass through one intermediary to another destination, revealing chained or relayed connections. It helps identify abuse such as pivoting, email forwarding chains or authentication relay attacks. Defenders inspect hop patterns and unexpected intermediaries; attackers use relays to obscure origin and control.
What Relay Pattern Analysis Reveals
Relay Pattern Analysis examines how traffic, identity signals, or session paths move through one intermediary before reaching a final destination. The value is not just in seeing a hop, but in recognising that the intermediary may be masking origin, redirecting control, or bridging two otherwise unrelated trust zones.
That makes the pattern useful for spotting abuse that looks ordinary at the packet or message level but becomes suspicious when the hop chain is considered as a whole. In practice, defenders use it to separate legitimate routing behaviour from relayed flows that should not exist in the environment.
Why Relay Chains Are Security Significant
Relay chains matter because they can turn a simple forwarding step into a security boundary crossing. An attacker can use a relay to hide the source of activity, move requests through a trusted intermediary, or reuse a legitimate path to reach a target that would otherwise reject direct access.
The same logic applies to email forwarding, proxy hops, middleware bridges, and authentication relays. When the intermediary is unexpected, the pattern can indicate abuse, misconfiguration, or a compromised component that is being used as a transit point rather than a destination.
For defenders, the key question is whether the intermediary is part of the normal architecture or a sign that trust is being extended farther than intended. That is why hop lineage, not just endpoint-to-endpoint connectivity, becomes important.
Common Relay Scenarios and What They Look Like
Relay Pattern Analysis often shows up in three broad situations. First, traffic relays, where a connection is proxied or bounced through another system. Second, identity relays, where an authentication exchange is forwarded or reused in a way that should not occur. Third, application relays, where messages, tokens, or callbacks travel through an unexpected middle layer.
These scenarios can be benign when they are explicit and documented, but suspicious when the intermediary appears without a clear business or technical reason. Repeated detours, inconsistent source attribution, and unusual hop order are common clues that the flow deserves investigation.
Because the analysis is pattern-based, it is often more useful for triage than for final attribution. It tells you that a relayed connection exists and that the trust path deserves scrutiny, but it does not by itself prove intent.
How Defenders Use Hop-Pattern Evidence
Effective use of this technique depends on comparing observed relay behaviour with expected topology, forwarding policy, and authentication design. The strongest detections come from combining network telemetry, identity logs, message traces, and intermediary inventory so that an unexpected hop can be validated against the environment’s intended routing model.
NHIMG’s MITRE D3FEND Guide is useful here because it frames relay analysis alongside defensive techniques such as process lineage analysis, network traffic policy mapping, and authentication event analysis. That perspective helps turn an observed relay into a concrete defensive hypothesis rather than a vague anomaly.
When relay chains are genuine, the goal is usually to understand why they exist and whether they preserve the intended security properties. When they are not, the same evidence can point to pivoting, forwarding abuse, or relay-based authentication attacks that need containment and review.
Risk and Threat Considerations
Relay chains can hide origin, expand trust across boundaries, and make malicious activity look like legitimate transit. That creates both detection risk and access risk, especially when an intermediary is trusted more than the original source.
Failure mechanism: An attacker or misconfigured system abuses a relay path to forward traffic, identity assertions, or session material through a trusted intermediary, then uses that intermediary’s legitimacy to reach a protected destination.
Impact: The result can be concealed pivoting, authentication relay abuse, forwarding abuse, weaker attribution, and wider compromise if the intermediary itself is trusted or privileged.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK addresses the attack and risk surface, while NIST SP 800-53 Rev 5 and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1090 — Proxy | Relay flows often use intermediaries to mask origin and reroute access. |
| Recommendation — Map unexpected intermediary hops to proxy and relay tradecraft, then hunt for pivoting in telemetry. | ||
| NIST SP 800-53 Rev 5 | AU-6 — Audit Record Review, Analysis, and Reporting | Relay analysis depends on correlating logs across source, intermediary, and destination. |
| IA-2 — Identification and Authentication (Organizational Users) | Authentication relays change how identities are proven and accepted across a path. | |
| AC-4 — Information Flow Enforcement | Relay patterns are fundamentally about controlling and observing allowed information flows. | |
| Recommendation — Correlate intermediary and destination logs to reconstruct the full hop chain. Validate that authentication events are bound to the intended source and not relayed through an untrusted intermediary. Enforce policy on allowed hop paths so only approved intermediaries can forward traffic. | ||
| NIST CSF 2.0 | DE.CM-01 — Anomalies and Events are Monitored | Relay detection relies on monitoring anomalous hop behaviour and unexpected intermediaries. |
| Recommendation — Monitor for unusual relay paths and compare them with the approved routing model. | ||
Practitioner Guidance
What to watch for: Focus on relay paths that appear without a documented business function, especially when the intermediary changes the apparent source, destination, or trust level of the connection. A sudden increase in hop complexity is often more important than a single suspicious event.
Practitioner takeaway: Treat relay analysis as a relationship problem, not just a packet problem, because the security question is whether the intermediary belongs in the trust chain at all.
Related resources from NHI Mgmt Group
- What breaks in a security programme when exploitability analysis is treated as simple pattern matching?
- Why do modern codebases require analysis beyond simple pattern matching to catch real security issues?
- What is the difference between semantic code analysis and traditional static pattern matching in AppSec?
- What is the difference between pattern-based semantic analysis and general-purpose static analysis?