-1' OR 5*5=25 --

Here's a comprehensive analysis of the SQL injection technique and related mathematical concepts:

SQL Injection Through Mathematical Abuses

The string -1' OR 5*5=25 -- demonstrates a classic SQL injection technique where arithmetic operations are used to bypass security checks. This works because:

• MySQL's string arithmetic converts non-numeric strings to 0 during operations, allowing malicious queries like ''-'' to evaluate to 0 blog.kotowicz.net
• The -- at the end serves as a comment delimiter in SQL, nullifying any following security checks
• The condition 5*5=25 always evaluates to true (1 in MySQL), making the entire WHERE clause true

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Mathematical Paradoxes and Type Conversion

The underlying principle relates to mathematical paradoxes where operations produce unexpected results:

• Type conversion ambiguities can make 'text'-0 evaluate to 0 in MySQL blog.kotowicz.net
• Similar to mathematical fallacies like the "proof" that 1=0 through division by zero math.hmc.edu
• The Four Fours puzzle shows how expressions can evaluate differently based on operation order wikipedia.org

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Security Implications

This injection technique reveals critical database vulnerabilities:

• Improper input validation allows arithmetic operations on strings
• Silent type conversions create security holes
• Simple mathematical truths (5*5=25) can bypass authentication

Prevention Methods

• Use parameterized queries instead of string concatenation
• Implement strict type checking
• Apply input sanitization for all user-provided data
• Disable verbose SQL error messages

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The example demonstrates how mathematical operations and type conversion quirks can be weaponized in SQL injection attacks, emphasizing the need for robust input validation in database programming.