1.2 Compare common security vulnerabilities
📘CCNP security (350-701)
Overview
Security vulnerabilities are weaknesses in systems, applications, or configurations that attackers can exploit. In the CCNP Security exam, you must understand what these vulnerabilities are, why they occur, and how they impact enterprise networks (on-premises, cloud, or hybrid).
This section breaks down each vulnerability in simple English with IT-focused examples, making it easy for students and non-IT beginners.
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1. Software Bugs
What is a software bug?
A software bug is an unintentional error in a program’s code that causes incorrect or unexpected behavior.
Why it happens
- Poor coding
- Lack of input validation
- Incorrect logic
- Missing error handling
- Incomplete testing
Why it is a vulnerability
Bugs can lead to:
- Application crashes
- Unauthorized access
- Privilege escalation
- Data leakage
- System compromise
IT environment example
A firewall OS update has a bug that incorrectly processes certain packets. Attackers exploit this bug to bypass firewall rules and gain access to protected systems.
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2. Weak / Hardcoded Passwords
Weak passwords
Easy-to-guess passwords like:
- admin123
- password
- welcome1
Attackers can crack these quickly using brute-force tools.
Hardcoded passwords
These are passwords written directly inside:
- Application source code
- Configuration files
- Firmware
Why they are dangerous
- Cannot be changed easily
- If leaked, every device/application using it becomes vulnerable
- Attackers who reverse-engineer code can extract the password
IT environment example
A router’s firmware contains a hidden hardcoded admin password. Attackers find it online and use it to log into thousands of routers worldwide.
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3. OWASP Top Ten
OWASP lists the most critical web application vulnerabilities. You should know selected items from this list for the exam.
Current OWASP Top Ten (2021 version, still used widely):
- Broken Access Control – users can access things they shouldn’t.
- Cryptographic Failures – weak/missing encryption.
- Injection – attackers inject malicious code (e.g., SQL).
- Insecure Design – weak architecture decisions.
- Security Misconfiguration – default configs, unused services, open ports.
- Vulnerable and Outdated Components – old libraries, old OS.
- Identification and Authentication Failures – weak logins.
- Software and Data Integrity Failures – untrusted updates, CI/CD issues.
- Security Logging and Monitoring Failures – lack of alerts or logs.
- Server-Side Request Forgery (SSRF) – attackers force server to access internal systems.
IT example
A web app uses outdated PHP libraries. A known vulnerability is published, and attackers exploit it to steal customer data.
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4. Missing Encryption Ciphers
What it means
Systems rely on encryption to secure data.
If encryption ciphers are:
- Missing
- Disabled
- Outdated (e.g., DES, RC4)
Then data is not protected.
Common weak or deprecated ciphers
- DES
- 3DES
- RC4
- MD5
- SHA-1
Why it is dangerous
Attackers can:
- Decrypt communications
- Perform man-in-the-middle attacks
- Steal credentials
- Modify data in transit
IT example
A VPN gateway still allows clients to connect using SHA-1. Attackers exploit this weak cipher and decrypt captured VPN traffic.
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5. Buffer Overflow
What is it?
A buffer overflow happens when a program writes more data into memory than it can handle.
Why it is dangerous
Attackers can:
- Crash the application
- Insert malicious code
- Gain system-level privileges
How attackers use it
They send specially crafted packets or input that exceed the expected size.
IT environment example
A DNS server has a buffer overflow vulnerability. Attackers send a long DNS query causing the server to execute malicious code, giving the attacker root access.
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6. Path Traversal
What is it?
A vulnerability where attackers manipulate file paths to access files and directories outside the allowed location.
They use patterns like:
../../etc/passwd
Why it’s dangerous
Attackers may:
- Read sensitive files
- Read application source code
- Modify configuration files
IT environment example
A web application allows downloading log files using a URL parameter. Attackers modify the parameter to:
download?file=../../../config/database.yml
This reveals database credentials.
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7. Cross-Site Scripting (XSS)
What is it?
XSS allows attackers to inject malicious scripts (JavaScript) into websites.
Common types
- Stored XSS: injected code is permanently stored in database
- Reflected XSS: script is part of the URL and executed immediately
- DOM-based XSS: script executes in the user’s browser due to insecure client-side code
Why XSS is dangerous
Attackers can:
- Steal cookies
- Hijack sessions
- Redirect users to malicious sites
- Modify website content
IT example
A helpdesk portal does not filter inputs. Attackers post a malicious script in a support ticket comment. The script runs when staff open the ticket and steals their session cookies.
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8. Cross-Site Request Forgery (CSRF)
What is CSRF?
An attacker tricks a logged-in user into performing actions they did not intend.
Why it works
Web applications often trust actions done through the user’s browser session.
Why CSRF is dangerous
Attackers can force users to:
- Change account settings
- Approve financial transactions
- Upload malicious files
- Modify system configurations
IT example
A user is logged into a cloud-admin portal.
They open a malicious webpage that silently sends a request to:
https://portal.company.com/admin/delete-user?id=100
Because the user’s session is active, the action succeeds.
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🚀 Final Exam-Focused Summary
For the CCNP Security exam, remember these core points:
✔ Software bugs
Coding errors → system crashes, privilege escalation, and data exposure.
✔ Weak/hardcoded passwords
Easy attack vector → brute force, credential stuffing, reverse engineering.
✔ OWASP Top Ten
Essential list of most critical web vulnerabilities.
✔ Missing encryption ciphers
Old or missing ciphers → data leaks and MITM attacks.
✔ Buffer overflow
Too much data → malicious code execution.
✔ Path traversal
Manipulated file paths → access to sensitive server files.
✔ XSS
Injected scripts → session hijacking, cookie theft.
✔ CSRF
Users unknowingly perform actions → unauthorized system changes.
