Expert Witness Analysis of MAC Address Spoofing in Securities Fraud Cases

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How Network-Level Evidence Supports Legal Investigations

When trades are made over private networks, there’s an expectation that every transaction originates from an authorized device. But in certain securities fraud cases, that assumption doesn’t hold. Discovery Engineering provides electrical engineering expert witness services that help attorneys evaluate technical evidence when spoofed MAC (Media Access Control) addresses are involved. This type of fraud can allow unauthorized trades to appear legitimate, creating exposure for brokers, traders, and institutions. Understanding how network infrastructure identifies devices—and how that identity can be manipulated—is essential when investigating allegations of unauthorized trades or internal compliance breaches.

Identifying and Investigating MAC Address Spoofing

What Is a MAC Address and Why It Matters in Litigation

Every networked device has a MAC address—an embedded hardware identifier assigned to the network interface card (NIC). Switches and routers use MAC addresses to direct traffic to the right device. In secure financial environments, MAC addresses often serve as part of the identity verification process. If a trading platform is configured to allow trades only from approved terminals, the system may check for matching MAC addresses before permitting access.

However, MAC addresses can be spoofed. A user with technical knowledge can reconfigure a device’s network interface to impersonate another device. If done successfully, the network treats the spoofed device as legitimate, making it difficult to trace unauthorized activity through standard logs. For attorneys handling compliance violations, insider trading, or system integrity disputes, this raises critical questions: Did the trades come from an approved terminal? Or was a different device masquerading as one?

Discovery Engineering’s Role in MAC Address Spoofing Investigations

Discovery Engineering investigates these scenarios by reviewing how devices interacted with the network at the time of disputed activity. In a documented case involving a $40 million deficit from unauthorized cross-trades, the firm analyzed whether trades were initiated from spoofed MAC addresses on a private network. This case was part of a FINRA arbitration and required review of switch logs, MAC tables, and authentication metadata.

Key technical areas examined included:

• MAC table entries and their timestamped port mappings
• Switch-level forwarding logs indicating where each device physically connected
• ARP (Address Resolution Protocol) data that resolves MAC-to-IP assignments
• Patterns consistent with device spoofing, including rapid MAC address changes

Unlike standard IT consultants, Discovery Engineering provides an engineering analysis. This includes validating whether MAC address activity aligns with the known configuration of a trading environment, and whether the timing of MAC events corresponds to legitimate access or manipulation.

Correlating Technical Records with Legal Timelines

Expert witnesses from Discovery Engineering do more than interpret raw logs—they help legal teams match technical data with case timelines. For example, if a trade was executed at 10:05 a.m., the expert can examine whether the switch log recorded any new MAC address activity on the trading floor around that time. If the log shows the MAC address of a remote or previously inactive terminal suddenly appearing, that can suggest spoofing.

This type of analysis allows counsel to support or challenge witness statements, test the reliability of compliance systems, and determine whether policies based on device identity were actually enforceable. These technical points must be explained clearly to a non-engineering audience, including arbitrators, opposing counsel, and the court.

Engineering Methods That Strengthen Network Evidence

Technical review in these cases is grounded in electrical engineering and telecommunications principles. MAC addresses operate at Layer 2 of the OSI model. Discovery Engineering brings an understanding of how physical connections, switch firmware, and broadcast domains affect device recognition. If a device spoofed a MAC address but was connected to a different switch port than the genuine device, the discrepancy may be visible in archived logs.

Experts also assess the timing behavior of the spoofed address. For instance, if two devices appear to use the same MAC address within seconds on different parts of the network, that’s a strong indicator of spoofing. These analyses rely on engineering methods such as:

• Time-domain correlation of switch and router logs
• Signal path tracing using physical wiring documentation
• Device signature tracking through vendor-specific MAC prefixes

MAC spoofing undermines compliance systems that rely on device ID as a proxy for user authentication. If multiple users can impersonate a trusted terminal, internal controls may not prevent unauthorized trades—even when access rules appear to be in place. Experts can help identify whether these policies were technically sound or exposed to manipulation.

MAC Spoofing Detection Process

Presenting Technical Findings in a Legal Context

Discovery Engineering prepares reports and testimony that are formatted for legal use, not just technical review. Reports typically include annotated diagrams of the network, timelines showing when each MAC address appeared, and summaries of how spoofing could or could not have occurred based on the evidence.

In arbitration or deposition, technical testimony is delivered using plain language, supported by visual aids when necessary. The goal is not just to explain what happened on the network, but to provide a foundation for the court or panel to evaluate whether the activity in question aligned with or violated expected procedures.

How Expert Network Analysis Can Shape Legal Strategies

When internal compliance systems depend on hardware identity, MAC address spoofing can expose an organization to fraud and regulatory risk. Understanding how a device was identified, whether that identity was legitimate, and how the network responded are all essential in resolving these disputes.

Attorneys handling complex trading, financial misconduct, or unauthorized access cases benefit from early expert engagement. By reviewing technical records through the lens of electrical engineering and network behavior, Discovery Engineering provides testimony that supports fact-based legal analysis and helps build a coherent, data-supported case strategy.

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