An API is a contract between a caller and a callee. The most common forms of API abuse are caused by the caller failing to honor its end of this contract. For example, if a program fails to call chdir() after calling chroot(), it violates the contract that specifies how to change the active root directory in a secure fashion. Another good example of library abuse is expecting the callee to return trustworthy DNS information to the caller. In this case, the caller abuses the callee API by making certain assumptions about its behavior (that the return value can be used for authentication purposes). One can also violate the caller-callee contract from the other side. For example, if a coder subclasses SecureRandom and returns a non-random value, the contract is violated.
Dangerous Function: xp_cmdshell
xp_cmdshell cannot be used safely. It should not be used.xp_cmdshell launches a Windows command shell to execute the provided command string. The command executes either in the default system or a provided proxy context. However, there is no way to limit a user to prespecified set of privileged operations and any privilege grant opens up the user to execute any command string.