An intrusion detection system (IDS) is a software or hardware device that monitors network traffic and detects unauthorized or malicious activities, such as attacks, intrusions, or breaches. An IDS can provide valuable evidence for an information security team to investigate an alleged breach of an organization’s network, as it can capture and analyze the network traffic in real time or after the fact. An IDS can help to identify the source, type, scope, and impact of the breach, as well as to generate alerts and reports for further investigation.

File integrity monitoring software (FIM), security information and event management (SIEM) tool, and antivirus software are not single sources of evidence for an information security team to review. FIM software monitors files and directories on a network or system and detects changes or modifications that may indicate unauthorized access or tampering. SIEM tool collects and correlates data from various sources, such as logs, events, alerts, incidents, and threats, and provides a unified view of the security posture of an organization. Antivirus software scans files and programs on a network or system and detects malware infections that may compromise the security or functionality of the system.

However, these tools are not sufficient by themselves to provide conclusive evidence for an information security team to investigate an alleged breach of an organization’s network. They may provide some clues or indicators of compromise (IOCs), but they may also generate false positives or negatives due to various factors, such as configuration errors, user behavior, benign activities, or evasion techniques. Therefore, an information security team should use multiple sources of evidence from different tools and methods to verify the validity and reliability of the findings.

References = CISM Manual, Chapter 6: Incident Response Planning (IRP), Section 6.2: Evidence Collection1

1: https://store.isaca.org/s/store#/store/browse/cat/a2D4w00000Ac6NNEAZ/tiles