Python Penetration Testing Cookbook

Format string exploitation

A format string is an ASCIIZ string that contains text and format parameters. The format string vulnerability occurs when the submitted data of an input string is evaluated as a command by the application. With the help of this method, the attacker could execute code, read the stack, and may cause a segmentation fault. Format string vulnerability exist in most of the printf family functions, such as printf, sprintf, and fprintf. These are the common parameters that can be used in format string vulnerabilities:

• "%x": It reads data from the stack
• "%s": It reads character strings from the process memory
• "%n": It writes an integer to locations in the process memory
• "%p": It's external representation of a pointer to ...