The fundamental error made by the incident response team was violating a core principle of digital forensics: the preservation of original evidence. By running the zip disk directly on a system, even an isolated one, they actively used and executed its contents. This action constitutes evidence tampering because it alters the original media (e.g., changing file access times, metadata) and, in this case, triggered a destructive payload. Proper procedure dictates creating a bit-for-bit forensic image of the evidence and conducting all analysis on the copy, leaving the original evidence untouched and preserved in its initial state.

A. They examined the actual evidence on an unrelated system Using an isolated or "unrelated" system (a forensic workstation) is a correct procedure. The error was not the choice of system but the failure to create a forensic image before analysis.
B. They attempted to implicate personnel without proof Shortlisting potential suspects based on access and opportunity is a standard part of an investigation. It is not a procedural error in evidence handling, which was the critical mistake.
D. They called in the FBI without correlating with the fingerprint data Escalating a major cyberattack on a government entity to law enforcement like the FBI is an appropriate and often necessary step. There is no procedural requirement to analyze fingerprint data first.

1. National Institute of Standards and Technology (NIST) Special Publication 800-86, Guide to Integrating Forensic Techniques into Incident Response. Section 3.3, "Examination," states, "Forensic examination should be done on a copy of the evidence, not the original. This prevents the original from being modified by the examination." The team's action of running the original disk directly contradicts this guideline.

2. Request for Comments (RFC) 3227, Guidelines for Evidence Collection and Archiving. Section 3, "Guiding Principles," emphasizes the need to "minimize changes to the data as you are collecting it." Running the disk directly caused maximum change, violating this principle. The document advocates for creating a bit-for-bit copy for analysis.

3. Casey, E. (2011). Digital Evidence and Computer Crime: Forensic Science, Computers, and the Internet (3rd ed.). Academic Press. Chapter 4, "Digital Evidence," outlines the best practice of creating a physical image (a bit-stream copy) of the original media before performing any analysis to prevent alteration of the original evidence. This is a foundational text in digital forensics taught in university curricula.