Integer Overflow
What is an Integer Overflow?
Integer overflows are a type of vulnerability that occurs when the result of an arithmetic operation exceeds the range of values that can be represented by a particular data type, such as an integer.
In other words, an integer overflow occurs when the result of an operation is too large to be represented by the data type that stores it.
For example, if an integer data type is defined with a range of -128 to 127 and a program attempts to add 130 to a value of 127, an integer overflow will occur, and the value will "wrap around" to become -127. This can lead to unexpected and potentially dangerous behavior, such as crashes, incorrect calculation results, or security vulnerabilities.
Check out this video for a high-level explanation:
What is the impact of Integer Overflows?
Integer overflow vulnerabilities can be exploited by attackers to perform a variety of attacks, such as:
- Buffer overflows: An integer overflow can be used to overwrite memory outside the bounds of an array, which can result in a buffer overflow vulnerability. This can allow an attacker to execute arbitrary code, modify data, or crash the program.
- Denial-of-service (DoS) attacks: An integer overflow can be used to cause a program to consume excessive resources or crash, resulting in a DoS attack.
- Logic bypasses: An integer overflow can be used to bypass security checks, such as input validation, authentication, or access control. This can allow an attacker to access unauthorized resources or perform actions that they are not authorized to perform.
How to prevent Integer Overflows?
To prevent integer overflow vulnerabilities, here are some best practices to follow:
- Use appropriate data types: Use appropriate data types that can represent the range of values that are expected to be processed. For example, use a larger integer data type, such as a "long" instead of an "int", to avoid overflowing the range of values.
- Bounds checking: Implement bounds checking to prevent arithmetic operations from exceeding the range of values that can be represented by a data type. This can involve checking the range of values before performing arithmetic operations or using libraries or tools that provide built-in checks.
- Input validation: Validate all user input to ensure that it is of the expected data type and within the acceptable range of values. This can prevent attackers from manipulating input values to cause integer overflows.