Understanding Windows Logs and Linux Logs in Cybersecurity

Logs in computers

Introduction

Logs are one of the most important parts of cybersecurity and system monitoring. Every action happening inside an operating system — login attempts, software installation, privilege escalation, malware activity, or system errors — leaves traces in logs. Security analysts and SOC (Security Operations Center) teams use these logs to detect attacks, investigate incidents, and monitor suspicious behavior.

This blog explains the basics of Windows Logs, Linux Logs, important Event IDs, and the difference between how both operating systems manage logging.

What Are Windows Logs?

Windows systems maintain logs through a built-in utility called Windows Event Viewer. These logs help administrators and security analysts understand what activities occurred inside the system.

The logs can be viewed using:

• Windows Event Viewer
• PowerShell commands
• SIEM tools like Splunk, QRadar, or Microsoft Sentinel

Types of Windows Logs

1. System Logs

System logs contain events related to:

• Device drivers
• Hardware issues
• System services
• Boot and shutdown processes

These logs help troubleshoot operating system problems.

2. Security Logs

Security logs are the most important logs for cybersecurity professionals.

They record:

• Login attempts
• Failed login attempts
• Account creation
• Privilege usage
• Policy changes

SOC analysts mainly monitor these logs during investigations.

3. Application Logs

Application logs record events generated by installed software or applications.

Examples:

• Application crashes
• Software updates
• Application errors
• Installation events

4. Setup Logs

Setup logs contain details related to:

• Application installation
• Windows updates
• System setup activities

These logs are useful when troubleshooting update failures or installation issues.

5. Forwarded Events

Forwarded events are logs collected from remote Windows machines across a network.

In enterprise environments, logs from multiple systems are forwarded to a centralized server for monitoring and analysis.

Sysmon (System Monitor)

Sysmon is an advanced Windows monitoring tool from Microsoft Sysinternals.

It provides deep visibility into:

• Process creation
• Network connections
• File modifications
• Registry changes
• Malware behavior

Sysmon is widely used by SOC analysts and threat hunters because it captures detailed system activity beyond normal Windows logs.

Useful PowerShell Commands for Windows Logs

1.View All Logs

Get-EventLog -List

2.View Logs from a Specific Category

Get-EventLog -LogName Security

Other categories include:

System
Application
Setup

3.View Latest 10 Security Events

Get-EventLog -LogName Security -Newest 10

4.Search by Event ID

Get-EventLog -LogName Security -InstanceId 4624

This command filters logs using Event IDs.

Important Windows Security Event IDs

Understanding Event IDs is very important for SOC analysts.

Event ID 4624 — Successful Logon

Indicates a successful login attempt.

Used to track:

• User login activity
• Remote logins
• Normal authentication behavior

Event ID 4625 — Failed Logon

Indicates a failed login attempt.

This is very important for detecting:

• Brute-force attacks
• Password guessing attempts
• Unauthorized access attempts

Multiple 4625 events within a short time may indicate an attack.

Event ID 4720 — New User Account Created

Generated when a new user account is created.

This can indicate:

• Legitimate administrator activity
• Persistence mechanisms used by attackers

Event ID 4672 — Special Privileges Assigned

This event appears when administrative privileges are granted.

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Often associated with:

• Administrator logins
• Privileged accounts
• Elevated access sessions

Event ID 4648 — Logon Attempt Using Explicit Credentials

Occurs when a user tries to access resources using different credentials.

Common during:

• “Run as Administrator”
• Remote access
• Credential-based access attempts

Event ID 4616 — System Time Changed

Generated when system time is modified.

Attackers sometimes manipulate time settings to hide traces or evade detection.

Event ID 1102 — Audit Log Cleared

One of the most critical security events.

Indicates that security logs were cleared.

This may suggest:

• Anti-forensics activity
• Attackers attempting to remove evidence

SOC analysts usually treat this as a high-priority alert.

Event ID 4732 — User Added to Security-Enabled Local Group

Indicates a user was added to a privileged group.

Can indicate:

• Privilege escalation
• Unauthorized administrative access

Detecting Attacks Using Windows Logs

1.Detecting Brute-Force Attacks

Check for repeated:

• Event ID 4625 (Failed Logon)

A large number of failed logins may indicate password attacks.

2.Detecting Persistence

Monitor:

• Event ID 4720 (New User Created)
• Event ID 4732 (Added to Privileged Group)

Attackers often create hidden accounts to maintain access.

3.Detecting Malware Activity

Using Sysmon logs:

• Event ID 1 → Process Creation
• Event ID 3 → Network Connection

These help identify suspicious programs and malicious outbound connections.

Linux Logs

Linux systems use the Syslog standard for logging.

Unlike Windows logs, Linux logs are mostly text-based and stored inside the /var/log/ directory.

Linux categorizes logs using:

1. Facility
2. Severity

i) Linux Log Facilities

Facilities identify the source of the log.

Examples:

Facility Purpose
auth -> Login attempts authentication
mail -> Email server activity
kernel -> Kernel and core OS events
cron -> Scheduled background tasks

ii) Linux Severity Levels

Severity shows how serious the event is.

The levels range from:

Level-0 = Emergency-system unusual | 7 = Debug-normal details

Lower numbers indicate more critical issues.

Difference Between Windows Logs and Linux Logs

Windows Logs | Linux Logs

Structured and categorized | Mostly text-based

Uses Event IDs | Uses facilities and severity

Stored in XML/Binary format | Stored as plain text files

Viewed using Event Viewer | Viewed using commands like grep, cat, tail

Example: Event ID 4625 | Example: /var/log/auth.log

Linux Logs

Example of Windows Log Entry

Event ID: 4625
Task Category: Logon
Logon Type: 3
Account for which logon failed: Administrator

This indicates a failed login attempt.

Example of Linux Log Entry

May 21 20:15:22 ubuntu-server sshd[10432]:
Failed password for root from 192.168.1.50 port 54322 ssh2

This indicates a failed SSH login attempt.

Why Logs Are Important in Cybersecurity

Logs help organizations:

• Detect cyberattacks
• Investigate incidents
• Track user activity
• Identify malware behavior
• Monitor privilege escalation
• Perform forensic analysis
• Meet compliance requirements

Without logs, security teams cannot properly investigate or understand attacks.

Conclusion

Windows and Linux logs are foundational components of cybersecurity monitoring. Windows systems rely heavily on Event IDs and structured logging, while Linux uses text-based Syslog mechanisms with facilities and severity levels.

For SOC analysts, understanding important Event IDs like 4624, 4625, 1102, and Sysmon events is essential for detecting threats such as brute-force attacks, privilege escalation, persistence, and malware activity.

Learning log analysis is one of the strongest skills for anyone preparing for:

SOC Analyst roles

• Threat Hunting
• Incident Response
• Digital Forensics
• System Administration

Mastering logs means understanding the story behind every event happening inside a system.