Course 13 - Network Forensics | Episode 4: Log Analysis, SIM Correlation, and Network Attack Signature Detection

In this lesson, you’ll learn about:Log analysis fundamentals and why logging is essential for security visibilitySIM (Security Information and Event Management) correlation and event analysisNetwork attack signature detection using tools such as Snort and packet capture analysis1. Introduction to Logging and Security Visibility Effective security monitoring depends on logging the right information and establishing baselines for normal behavior. A common challenge is that security tools—especially IDS sensors—produce many false positives, which can lead analysts to ignore real threats (as seen in major breaches such as Home Depot). 2. Logging Strategy and Log Integrity Logging Strategy Essentials Organizations must implement:A clear logging strategyStructured and normalized log dataCentralized loggingReal-time and continuous monitoringLong-term storage for historical correlationWhat Must Be LoggedUnsuccessful authentication attemptsExample: 100 → 10,000 attempts indicates brute-force or dictionary attacksSuccessful authentication attemptsExample: 1,000 → 20,000 successful logins indicates compromised credentials being reusedMaintaining Log Integrity Logs must be treated like financial ledgers:Log storage must be read-onlyUse hashing to ensure logs are not modifiedUse encryption to protect confidentialityLarge storage capacity is required to retain logs for long-term, low-and-slow attack correlationSyslog is the most common centralized log transport and storage method3. SIM (Security Information and Event Management) Correlation What SIMs Do SIM systems do not store logs; they:Collect and centralize logs from many devices (nodes, routers, switches, appliances)Correlate and analyze eventsProvide near real-time security violation alertsReveal attack patterns that individual log sources might not showLog Sources for SIM Analysis SIMs typically gather logs from:Files (data logs)Operating SystemsNetwork trafficApplicationsAudit Reduction Tools Because audit logs can be massive, tools are used to:Eliminate unnecessary dataFocus analysts on events of significance4. Network Attack Signature Detection Signature detection identifies patterns that indicate malicious activity. Tools such as Snort and packet capture analysis are commonly used. Types of Signatures A. Standard Communication SignaturesICMP ping has a predictable payload (A B C D …)TCP three-way handshake (SYN, SYN-ACK, ACK) helps identify typical connections such as FTP (21) or Telnet (23)B. Reconnaissance ScansPing SweepsEcho requests sent to incrementing IP addressesPort ScansOne source IP sending SYN packets to many ports on one hostModern scanners use non-sequential methodsStealth Scans (used to evade detection)ACK scansSYN stealth scansFIN scans (only FIN flag)NULL scans (no flags)Christmas (Xmas) ScansFlags typically set: FIN, URG, PUSHSnort distinguishes traditional Xmas scans from tools like Nmap (which uses only FUP flags)C. Denial of Service (DoS) AttacksPing of Death – oversized ICMP packetsSYN Flood – large numbers of half-open TCP connections exhausting port capacityD. Trojans and BackdoorsIdentified by traffic on known Trojan portsExample:Netbus → port 12345Back Orifice → port 313375. The Objective of Correlation and Detection The primary goal is to:Detect attack patterns before they completeCombine behavior-based insight with signature-based detectionContinuously update rules and detection logic as threats evolveTools like Snort rely on constantly updated rule sets to stay effective against modern attacks.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy