Define the term "buffer overflow" and its impact on application security.

A buffer overflow is a type of software vulnerability that occurs when a program writes more data to a block of memory, or buffer, than it was allocated to hold. This can lead to unintended consequences such as overwriting adjacent memory, corrupting data, and potentially causing the execution of arbitrary code. Buffer overflows are a common source of security vulnerabilities and can be exploited by attackers to compromise the security of a system.

  1. Buffer: A buffer is a temporary storage area in a program's memory used to hold data. It has a fixed size allocated during program execution.
  2. Overflow: A buffer overflow occurs when more data is written to a buffer than it can hold, causing the excess data to overflow into adjacent memory locations.
  3. Impact on Security: The impact of a buffer overflow on application security is significant. Exploiting a buffer overflow can allow attackers to overwrite critical data structures, inject malicious code into the program's memory, and gain unauthorized access or control over the system.
    • Code Execution: By carefully crafting the overflowed data, an attacker can overwrite a function's return address or other pointers, redirecting the program's execution flow to malicious code they injected into the buffer.
    • Denial of Service (DoS): In some cases, buffer overflows may cause a program to crash, leading to a denial of service. While this might not provide direct control to an attacker, it can still disrupt the normal operation of a system.
    • Data Corruption and Leakage: Buffer overflows can result in unintended data corruption, leading to unpredictable behavior or disclosure of sensitive information.
  4. Prevention and Mitigation: To mitigate the risk of buffer overflows, developers should follow secure coding practices, such as bounds checking, input validation, and using secure coding libraries. Additionally, modern programming languages and frameworks often include built-in mechanisms to prevent buffer overflows, like array bounds checking and memory safety features.