Obscuring Control Flow Using Pointers

Created the Monday 18 March 2019. Updated 6 months, 2 weeks ago.

The use of pointers in a program can be an issue for disassemblers, because pointers can be used in complex ways that are difficult for the disassembler to accurately interpret. This can make it more difficult for the disassembler to generate correct disassembly output, and can also make it more difficult for analysts to understand the program's behavior.

Pointers are a common programming idiom used in C and C++ to reference memory locations and manipulate data in memory. They are typically implemented as variables that contain the memory address of another variable. This allows the programmer to access and modify the data stored at that memory address, without having to know the exact memory address of the data.

Technique Identifier

U0214

Technique Tags

Pointers Anti-disassembling Control flow Program behavior Memory addresses Data manipulation

Code Snippets

Description

This code ncludes a real function, my_function, which is called by the original and obfuscated instructions. This allows the code to demonstrate the intended behavior of the original instructions, which is to declare and initialize the variable x, declare and initialize the pointer ptr, and use the pointer ptr to dereference and modify the value of x.

However, the obfuscated instructions use pointers in a more complex way, by declaring and initializing two additional pointers, ptr1 and ptr2. This makes it more difficult for the disassembler to accurately interpret the instructions and generate correct disassembly output.

#include <iostream>

int my_function() {
    std::cout << "Hello, world!" << std::endl;
    return 0;
}

int main() {
    // Original instructions
    int x = 0x12345678;
    int *ptr = &x;
    *ptr = 0x87654321;

    // Obfuscated instructions using pointers
    int y = 0x12345678;
    int *ptr1 = &y;
    int *ptr2 = ptr1;
    *ptr2 = 0x87654321;

    return 0;
}

Additional Resources

External Links

The resources provided below are associated links that will give you even more detailed information and research on current evasion technique. It is important to note that, while these resources may be helpful, it is important to exercise caution when following external links. As always, be careful when clicking on links from unknown sources, as they may lead to malicious content.

http://staff.ustc.edu.cn/~bjhua/courses/security/2014/readings/anti-disas.pdf