What is GCC stack guard?

What is GCC stack guard?

Since 1998, StackGuard patches to GCC have been used to protect entire distributions from stack smashing buffer overflows. Since StackGuard is a mature technology, even see- ing re-implementations in other compilers, we propose that GCC adopt StackGuard as a stan- dard feature.

What is StackGuard?

StackGuard is a compiler extension that enhances the executable code produced by the compiler so that it detects and thwarts buffer-overflow attacks against the stack. The effect is transparent to the normal function of programs.

What causes heap overflow?

A heap overflow is a form of buffer overflow; it happens when a chunk of memory is allocated to the heap and data is written to this memory without any bound checking being done on the data.

How does canary variable detect buffer overflow attack?

Terminator canaries use the observation that most buffer overflow attacks are based on certain string operations which end at string terminators. This prevents attacks using strcpy() and other methods that return upon copying a null character, while the undesirable result is that the canary is known.

What is stack smashing in C?

Stack smashing occurs when a buffer overflow overwrites data in the memory allocated to the execution stack. More often, a buffer overflow in the stack segment can lead to an attacker executing arbitrary code by overwriting a pointer address to which control is (eventually) transferred.

How can we prevent stack corruption?

One method to prevent stack overflow is to track the stack pointer with test and measurement methods. Use timer interrupts that periodically check the location of the stack pointer, record the largest value, and watch that it does not grow beyond that value.

Can Terminator Canaries be overwritten by gets?

Terminator canaries This type of protection can be bypassed by an attacker overwriting the canary with its known values and the return address with specially-crafted value resulting in a code execution.

Can you overflow the heap?

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Buffer overflows generally lead to crashes.

Do stack canaries detect overflow?

A stack canary is a value placed on the stack so that it will be overwritten by a stack buffer that overflows to the return address. It allows detection of overflows by verifying the integrity of the canary before function return.

What is canary value?

In computer science, and in particular computer security and code generation, the use of canary values is a strategy to detect buffer overflow attacks at run time, without requiring the programmer to modify any source code.