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Introduction:
The line between offensive security and defensive hardening has never been thinner. Modern ethical hackers and penetration testers wield a sophisticated arsenal of built-in system commands and specialized tools to probe for weaknesses, mirroring the exact techniques of malicious actors. This article provides a verified command-line toolkit to elevate your security testing methodology, from reconnaissance to vulnerability validation.
Learning Objectives:
- Master fundamental and advanced command-line techniques for system reconnaissance and vulnerability assessment.
- Learn to leverage built-in OS tools for lateral movement and privilege escalation simulations.
- Develop the skills to validate common web application and API security flaws manually.
You Should Know:
1. System Reconnaissance & Enumeration
The first step in any security assessment is understanding the target environment. These commands provide a wealth of information about users, networks, and system configurations.
Windows:
systeminfo whoami /all net user net localgroup administrators netstat -ano ipconfig /all
Linux:
uname -a cat /etc/passwd id sudo -l netstat -tulpn ss -tulpn
Step-by-step guide: After gaining initial access, whether via a shell or physical access, start with `whoami` and `id` to understand your current privileges. Use `systeminfo` on Windows or `uname -a` on Linux to get OS details. Network commands like `netstat` and `ss` reveal active connections and listening ports, which can identify potentially vulnerable services. Always check `sudo -l` on Linux to see if your user can run any commands with elevated privileges.
2. Network Discovery & Scanning
Discovering live hosts and identifying open ports is crucial for mapping the attack surface.
Built-in Tools:
ping <target> arp -a (Windows & Linux) nslookup <domain> (or dig on Linux)
PowerShell (Windows):
Test-NetConnection <target> -Port <port> Get-NetTCPConnection | where State -Eq Listen
Bash (Linux):
for i in {1..255}; do ping -c 1 192.168.1.$i | grep "bytes from"; done
Step-by-step guide: Use simple `ping` sweeps to identify live hosts on a network segment. The `arp -a` command will show the ARP cache, revealing other machines your system has communicated with. For internal port checks, PowerShell’s `Test-NetConnection` is a powerful native alternative to telnet. The bash `for` loop exemplifies how to script a basic ping sweep without specialized tools.
3. File System Exploration & Data Hunting
Sensitive data often resides in configuration files, logs, and user directories.
Windows:
dir /s password == .config == .xml findstr /si password .txt == .xml == .ini Get-ChildItem -Path C:\ -Include pass == .config -File -Recurse -ErrorAction SilentlyContinue | Select-Object FullName
Linux:
find / -name ".php" -type f 2>/dev/null find / -name passwd 2>/dev/null find / -perm -4000 2>/dev/null Find SUID files grep -r "password" /etc/ 2>/dev/null locate .bak
Step-by-step guide: The `find` command is indispensable on Linux for locating files with specific names, extensions, or permissions. The `-perm -4000` flag finds SUID binaries, a common privilege escalation vector. On Windows, `findstr` is the equivalent of `grep` for searching file contents. Always search for common configuration filenames and extensions (.config, .xml, .bak) that may contain hardcoded secrets.
4. Process and Service Interrogation
Identifying running applications and services can reveal outdated software or misconfigurations.
Windows:
tasklist /svc
sc query state= all
Get-Service | Where-Object {$_.Status -eq 'Running'}
wmic product get name, version
Linux:
ps aux top -n 1 -b systemctl list-units --type=service --state=running dpkg -l (Debian/Ubuntu) rpm -qa (RedHat/CentOS)
Step-by-step guide: Use `tasklist /svc` or `ps aux` to get a detailed list of all running processes and their associated services. Cross-reference these with known vulnerable software versions. The `wmic` and dpkg/rpm commands list all installed application packages, helping build a software inventory for vulnerability mapping. Check running services with `systemctl` or `sc query` to identify unnecessary services that could be hardened or disabled.
5. User and Privilege Management
Understanding user accounts, groups, and login sessions is key to lateral movement.
Windows:
net user <username> net group /domain quser /server:SERVER01 (Check logged-in users) klist (View Kerberos tickets)
Linux:
cat /etc/shadow last w cat ~/.bash_history
Step-by-step guide: The `net user` and `net group` commands are fundamental for enumerating users and groups on a Windows system, especially in a domain environment. `quser` checks for active remote desktop sessions on a target machine, which can be useful for targeting. On Linux, the `last` command shows login history, while the `w` command shows currently logged-in users and their activity.
6. Web Application & API Testing
Manual testing commands for uncovering common web vulnerabilities.
cURL for API Testing:
curl -X POST http://target.com/api/login -H "Content-Type: application/json" -d '{"user":"admin", "pass":"'password'"}'
curl -i http://target.com/portal/ --path-as-is Test for path traversal
curl -H "X-Forwarded-For: 127.0.0.1" http://target.com/admin Header Injection
OpenSSL for Service Testing:
openssl s_client -connect target.com:443 -servername target.com Check SSL/TLS openssl s_client -connect target.com:443 -tlsextdebug 2>&1 | grep "TLS server extension"
Step-by-step guide: cURL is the Swiss Army knife for manual web testing. Use it to craft custom HTTP requests, tamper with headers (-H), and send malicious JSON payloads (-d). The `–path-as-is` flag prevents cURL from normalizing paths, crucial for testing directory traversal attacks. OpenSSL’s `s_client` is essential for interrogating TLS/SSL configurations, checking certificates, and testing for vulnerabilities like Heartbleed.
7. Active Directory Enumeration (Windows)
Commands for assessing the security of a Windows Domain environment.
PowerShell:
Get-ADUser -Filter -Properties | Select-Object Name, SamAccountName, Description, PasswordLastSet, LastLogonDate Get-ADGroupMember "Domain Admins" -Recursive Get-DomainGPO (From PowerView) Test-ComputerSecureChannel Check domain trust
Command
nltest /domain_trusts dsquery computer -limit 0 dsquery user -limit 0
Step-by-step guide: PowerShell cmdlets like `Get-ADUser` and `Get-ADGroupMember` are powerful for enumerating Active Directory objects. The `Get-DomainGPO` cmdlet (from the PowerView module) retrieves Group Policy Objects, which can reveal misconfigurations. `nltest` and `dsquery` are legacy but still effective built-in tools for querying domain trusts, computers, and users without importing any external scripts.
What Undercode Say:
- The modern ethical hacker must be a master of native tools. Relying solely on automated scanners creates gaps in coverage; built-in commands provide deeper system insight and are often undetectable by security products.
- True expertise lies in chaining these simple commands into a sophisticated attack chain, turning seemingly benign system information into a critical vulnerability.
The proliferation of built-in tooling represents a double-edged sword. For defenders, it means that an attacker requires no malware download to conduct significant reconnaissance and exploitation, making detection based on tooling nearly impossible. For ethical hackers and red teams, it provides a stealthy and powerful arsenal that is already trusted on the system. The future of detection will shift from signature-based blocking of known hacking tools to behavioral analysis of command-line sequences and anomalous process execution chains. Security teams must now focus on auditing and monitoring the native tools themselves, understanding that `net.exe` and `powershell.exe` are just as potent as any downloaded exploit framework.
Prediction:
The techniques outlined above will become increasingly central to both attack and defense. As EDR (Endpoint Detection and Response) solutions improve at detecting off-the-shelf hacking tools, threat actors will deepen their reliance on “living off the land” binaries (LOLBins) and scripts. This will force a paradigm shift in defensive cybersecurity, moving from blacklisting applications to behavioral analytics that seek to identify malicious intent behind the use of legitimate system administration commands. The ethical hacking courses of the future will place a much heavier emphasis on this style of native tool mastery over graphical interface tools.
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IT/Security Reporter URL:
Reported By: Mrxfact0r99 Ethicalhacking – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
