Find where dispatcher is executed

hexdump/strings/entropy to find bytecode data

Write a simple Python noscript for pattern matching in binary

Build a simple VM Sample C code

This code creates a very simple program that checks a string, but instead of cmp directly, it first creates a simple bytecode and then an interpreter to execute it. This is a low-level simulation of a virtualizer and is very good for practice

Copy the sample code and compile it on your development machine/VM

vm.c

#include <stdio.h>
#include <string.h>
#include <stdint.h>

uint8_t prog[] = {
0x01, /* LOAD_INPUT */
0x10, /* expect length (16) or unused */
0x02, /* CMP_CONST */
'1','2','3','4',0, /* const "1234" + null */
0x03 /* HALT/END */
};

int run_vm(const char *input) {
int ip = 0;
while (ip < sizeof(prog)) {
uint8_t op = prog[ip++];
switch (op) {
case 0x01: // LOAD_INPUT -- store pointer (no-op for this demo)
// nothing to do; in real vm you'd load bytes to vm memory
break
case 0x02: { // CMP_CONST
const char *c = (const char*)&prog[ip];
ip += 5; // length of constant in this toy example
if (strcmp(input, c) == 0) return 1;
break
}
case 0x03:
return 0;
default:
return 0;
}
}
return 0;
}

int main(int argc, char **argv) {
if (argc < 2) { printf("usage: %s <pass>\n", argv[0]); return 0; }
if (run_vm(argv[1])) printf("Access granted\n");
else printf("Access denied\n");
return 0;
}

Compile:

gcc simple_vm.c -o simple_vm

Static analysis:

Run strings simple_vm
and see where the strings are

Open the file in IDA/Ghidra and look for the function run_vm. In the disassembler you will see a loop with switch/case and data prog[] this is the dispatcher/binary bytecode

Dynamic analysis:

Open the file with x64dbg and set a breakpoint on run_vm or on the address of the array prog

Run the program with different inputs and see how the dispatcher path changes

The goal is to understand where the bytecodes are, how the dispatcher works for them and where the comparison logic is

VM detection:
dispatcher loop bytecode table in data repeated calls to the interpreter

How do we use static and dynamic together: static finds the bytecode dynamic shows the runtime what is happening It turns out

devirtualization:
The first goal is to identify the dispatcher and data bytecodes and document the execution logic. Then the bytecodes can be extracted and their meaning reconstructed.

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Recon 2025 Breaking Obfuscated .NET Malware with Profiler Based Dynamic Binary Instrumentation

https://www.youtube.com/watch?v=jPDJ_Zo6jiY

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PE (Windows) Structure

ELF (Linux) Structure

Linux Kernel Exploitation

https://r1ru.github.io/categories/linux-kernel-exploitation

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Reverse Engineering Tools both Offensive and Defensive Operations can utilize

https://github.com/InfosecHouse/InfosecHouse/blob/main/re.md

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Deep Dive into a Modern Stealth Linux Kernel Rootkit

https://blog.kyntra.io/Singularity-A-final-boss-linux-kernel-rootkit

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List of Awesome Reverse Engineering Resources

https://github.com/wtsxDev/reverse-engineering

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Awesome Malware Development Resources

https://github.com/rootkit-io/awesome-malware-development

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بخش سوم بافر اور فلو

تفاوت های مهم بین استک هیپ و خطاهای off by one رو بررسی میکنیم

توضیح stack overflow
استک جاییه که فریم تابع ها قرار میگیره و معمولا بافر های محلی اینجا ساخته میشن
استک overflow زمانی رخ میده که نوشته های بیش از اندازه به بافر محلی برسن و بخش هایی مثل saved rbp و saved return address رو بازنویسی کنه
در عمل این نوع باعث کرش سریع میشه و معمولا به صورت overwrite روی فریم جاری قابل مشاهده هست

توضیح کد استک

در این کد یک تابع بافر محلی داره و با strcpy مقدار وارد شده رو کپی میکنه
دیدن کرش و بررسی saved return address در gdb هست

کد استک فایل stack.c

#include <stdio.h>
#include <string.h>

void vuln(char *s) {
char buf[32];
printf("inside vuln\n");
strcpy(buf, s);
printf("buf says %s\n", buf);
}

int main(int argc, char **argv) {
if (argc < 2) {
printf("usage stack input\n");
return 1;
}
vuln(argv[1]);
printf("returned normally\n");
return 0;
}

دستورات اجرا و دیباگ مربوط به استک
این دستورات رو اجرا کنید تا کرش و فریم رو ببینید

gcc -g stack.c -o stack
gdb --args ./stack $(python3 -c "print('A'*80)")

داخل gdb

break vuln
run
info frame
x/40gx $rbp
backtrace



Part Three Buffer Overflow

We examine important differences between stack, heap, and off‑by‑one errors

Explanation stack overflow
The stack is where function frames are placed and local buffers are usually allocated
A stack overflow occurs when writes exceed a local buffer and overwrite areas like saved rbp and the saved return address
In practice this type causes a fast crash and is usually visible as an overwrite on the current frame

Explanation stack code

In this code a function has a local buffer and uses strcpy to copy the supplied input
You will see the crash and inspect the saved return address in gdb

Stack source file stack.c

#include <stdio.h>
#include <string.h>

void vuln(char *s) {
char buf[32];
printf("inside vuln\n");
strcpy(buf, s);
printf("buf says %s\n", buf);
}

int main(int argc, char **argv) {
if (argc < 2) {
printf("usage stack input\n");
return 1;
}
vuln(argv[1]);
printf("returned normally\n");
return 0;
}

Commands to build and debug the stack
Run these commands to see the crash and inspect the frame

gcc -g stack.c -o stack
gdb --args ./stack $(python3 -c "print('A'*80)")

Inside gdb

break vuln
run
info frame
x/40gx $rbp
backtrace

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 BlackSuit Ransomware Actors Breached Corporate Environment

https://cybersecuritynews.com/blacksuit-ransomware-vmware-esxi

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این کنفرانس در زمینه ی مهندسی معکوس و توسعه اکسپلویت‌ هست

This conference is about reverse engineering and exploit development.


https://www.youtube.com/@reconmtl/videos

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Linux Kernel Rootkit

https://github.com/carloslack/KoviD

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Loadable Kernel Module Linux

https://github.com/Trevohack/Venom

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Windows Remote Execution Multitool

https://github.com/FalconOpsLLC/goexec

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Windows Drivers Reverse Engineering Methodology

https://voidsec.com/windows-drivers-reverse-engineering-methodology/

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Analysis Malicious Signed Driver

https://www.youtube.com/watch?v=NjXU-uH5P9Q

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Best Anti-Debugging Techniques

https://www.apriorit.com/dev-blog/367-anti-reverse-engineering-protection-techniques-to-use-before-releasing-software#best-anti-debugging-techniques-from-apriorit

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