Was ist SQL Injection?

SQL Injection ist eine kritische Sicherheitslücke, bei der ein Angreifer eigenen Datenbankcode über Eingabefelder einschleust. Dadurch kann er Daten auslesen, verändern oder löschen. Die Behebung erfolgt durch Prepared Statements, bei denen Benutzereingaben strikt als Text behandelt werden.

Was ist Cross-Site Scripting (XSS)?

XSS ist eine Schwachstelle, bei der Schadcode (meist JavaScript) in eine Webseite eingeschleust und im Browser anderer Nutzer ausgeführt wird. Angreifer können damit Session-Cookies stehlen oder Nutzer umleiten. Die Behebung erfolgt durch konsequente Ausgabecodierung (Output Encoding).

Was ist IDOR (Insecure Direct Object Reference)?

IDOR ist eine Zugriffskontroll-Schwachstelle, bei der ein System Benutzereingaben verwendet, um direkt auf interne Ressourcen zuzugreifen, ohne Berechtigungen zu prüfen. Beispiel: Ein Nutzer ändert eine ID in der URL und sieht fremde Daten. Behebung: serverseitige Autorisierungsprüfung bei jedem Zugriff.

Was sind die OWASP Top 10?

Die OWASP Top 10 sind die international anerkannte Liste der kritischsten Sicherheitsrisiken für Webanwendungen. Sie umfassen: Broken Access Control, Cryptographic Failures, Injection, Insecure Design, Security Misconfiguration, Vulnerable Components, Authentication Failures, Software Integrity Failures, Logging Failures und SSRF.

Security & Quality

Professional Code Review

I analyse your code for security risks, performance issues and technical debt – with concrete recommendations for action.

Security vulnerabilities & OWASP Top 10
Identify performance bottlenecks
Document technical debt
Concrete action plan

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100% free & non-binding

Why is a code review important?

Hidden security vulnerabilities and performance issues can be expensive.

A professional code review uncovers weaknesses before they become real problems. Whether you have taken over an existing application, want to audit an external developer, or simply want to ensure your code is up to date.

Find SQL Injection & XSS vulnerabilities
Identify performance bottlenecks
Document technical debt
Best practices and clean code

Common issues I find

CriticalSQL Injection vulnerabilities

CriticalUnprotected admin areas

HighOutdated dependencies with CVEs

HighMissing input sanitization

MediumN+1 query problems

InfoOutdated PHP syntax

What does a code review include?

Comprehensive analysis of your code with concrete recommendations

Security Analysis

Check for OWASP Top 10 vulnerabilities, SQL injection, XSS, CSRF and other security risks.

Performance Analysis

Identification of bottlenecks, slow queries, memory leaks and optimization potential.

Code Quality

Assessment of architecture, design patterns, readability and maintainability of the code.

Dependency Check

Analysis of used libraries for known security vulnerabilities and currency.

Documentation

Detailed report with prioritized recommendations and solution proposals.

Discussion

Personal follow-up discussion of all findings with explanations and Q&A.

Code Review Packages

Quick Check

Security Scan
Dependency Check
Short report (2-3 pages)
Prioritized recommendations
Detailed code analysis

Ideal for smaller projects or a first overview.

Deep Dive

Everything from Quick Check
Detailed code analysis
Performance profiling
Architecture assessment
Detailed report (10+ pages)
1h follow-up discussion

For complex projects and thorough analysis.

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What is checked in a code review?

A professional code review goes far beyond a simple glance at the source code. I check your code systematically across all relevant quality dimensions.

Modern web applications are complex – and vulnerabilities often hide in unexpected places. In the code review I combine automated analysis tools with manual inspection to find even subtle problems that scanners miss.

Security vulnerabilities

I check for SQL injection (direct database manipulation through user input), XSS (Cross-Site Scripting where malicious code is executed in the browser), CSRF (Cross-Site Request Forgery, unwanted actions on behalf of logged-in users), insecure file access, missing authentication checks and other OWASP Top 10 risks.

Performance bottlenecks

Slow queries, missing database indexes, inefficient loops, unnecessary API calls and memory leaks are identified through profiling and code analysis.

Code quality & maintainability

I assess readability, structure, adherence to coding standards, sensible naming of variables and functions, and the use of proven design patterns.

Documentation

Missing or outdated documentation significantly increases the effort for future developers. I check whether the code is understandably commented and the architecture is documented.

Who benefits from a code review?

A code review makes sense in various situations – not only for large projects.

Before launch

Before your application goes live, it is worth having the code thoroughly reviewed. This way you avoid embarrassing security incidents shortly after launch and start with a clean foundation.

When taking over a project

Are you taking over an existing application from another developer or a previous team? I provide you with a structured overview of the state of the code so you know what you are dealing with.

After an external developer

You have had a project developed externally and want to ensure the quality is right? An independent review gives you certainty and an objective second opinion.

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OWASP Top 10 CWE (MITRE) MDN Web Docs

Frequently Asked Questions about Code Review

What do you need for the code review?

Access to your Git repository (GitHub, GitLab, Bitbucket) or the source code as ZIP. Ideally also brief info about the application: what it does, which technologies are used, are there known issues?

How long does a code review take?

A Quick Check is usually ready within 2-3 working days. A Deep Dive requires 5-10 working days depending on project size. We discuss the exact timeline in advance.

Is my code safe with you?

Absolutely. I treat your code strictly confidentially, work on secured systems and delete the code after the review is complete. On request I sign an NDA.

Which programming languages can you review?

My focus is on PHP (Laravel, Symfony, CodeIgniter, WordPress) and JavaScript/TypeScript. For other languages I can draw on my network.

Can you also fix the problems found?

Yes, gladly. After the review you can commission me for the implementation of the recommendations. That way you have a contact person who already knows the code.

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