# OllyDbg$ for Penetration Testing
## Section 1: Installation and Configuration on Kali Linux
### 1.1 Overview of OllyDbg
OllyDbg is a powerful 32-bit assembler-level debugger for Windows applications. It is widely used in the fields of reverse engineering and malware analysis. OllyDbg allows security professionals to inspect how programs operate under the hood and identify vulnerabilities or malicious code. Its intuitive interface and robust features make it an essential tool in the toolkit of any penetration tester.
### 1.2 Installation of OllyDbg on Kali Linux
Although OllyDbg is a Windows application, it can be run on Kali Linux using Wine, a compatibility layer for running Windows applications on POSIX-compliant operating systems. Here’s a step-by-step guide to installing OllyDbg on Kali Linux:
#### Step 1: Update Your System
Before installation, ensure your Kali Linux system is up-to-date. Open a terminal and run:
"`bash
sudo apt update && sudo apt upgrade -y
"`
#### Step 2: Install Wine
To run Windows applications, you need to install Wine. Execute the following command:
"`bash
sudo apt install wine -y
"`
#### Step 3: Download OllyDbg
Visit the official website or a trusted repository to download the latest version of OllyDbg. You can use `wget` to download it directly to your machine:
"`bash
wget https://old.ollydbg.de/releases/OllyDbg_2.01.zip
"`
#### Step 4: Extract the Downloaded File
Once the download is complete, extract the ZIP file:
"`bash
unzip OllyDbg_2.01.zip
"`
#### Step 5: Navigate to the OllyDbg Directory
Change your directory to the folder where you extracted OllyDbg:
"`bash
cd OllyDbg_2.01
"`
#### Step 6: Run OllyDbg Using Wine
You can now run OllyDbg using Wine with the following command:
"`bash
wine OllyDbg.exe
"`
If all goes well, OllyDbg should start, and you will see the familiar interface ready for use.
### 1.3 Configuring OllyDbg
Upon launching, it is advisable to configure OllyDbg to suit your analysis needs:
1. **User Interface Customization**: Adjust the layout and panels according to your preference. You can drag and drop elements to organize the workspace.
2. **Plugins**: Install useful plugins like "OllyScript" for automation, "OllyDump" for extracting binaries, and "PEiD" for checking the packer used on an executable.
3. **Settings**: Navigate to `Options > Preferences` to adjust settings such as the debugging options and the appearance of the interface.
## Section 2: Step-by-Step Usage and Real-World Use Cases
### 2.1 Basic Usage of OllyDbg
Now that you have OllyDbg installed and configured, let's explore its basic usage through a practical example.
#### Example: Analyzing a Simple Executable
1. **Prepare the Target Executable**: Obtain or create a simple Windows executable. You can use a basic C program compiled with flags that prevent optimizations.
2. **Load Executable in OllyDbg**: Use `File > Open` to load your executable into OllyDbg.
3. **Start Debugging**: Press `F9` to run the program. You can set breakpoints where you suspect malicious activity might occur. Right-click on a line of code and select `Breakpoint > Toggle`.
4. **Inspecting the Call Stack**: When the execution hits a breakpoint, you can inspect the call stack to understand the flow of execution. Click on the `Call Stack` panel to view function calls leading up to the current execution state.
### 2.2 Real-World Use Cases
#### Case Study 1: Malware Analysis
In a real-world penetration testing scenario, you may encounter malware that needs to be dissected to understand its behavior. Using OllyDbg, you can:
– Set breakpoints at API calls used for file manipulation.
– Monitor changes made to the file system while the malware is executing.
– Analyze network activity initiated by the malware by incorporating additional tools like Wireshark.
"`markdown
# Sample Breakpoint for API Monitoring
"`assembly
; Setting a breakpoint on CreateFileA function
00401000: push 0x0
00401002: push 0x0
00401004: push offset FileName
00401009: push 0x40000000
0040100E: call 0x7C801D7A ; CreateFileA
"`
"`
#### Case Study 2: Vulnerability Discovery
Penetration testers often use OllyDbg to analyze applications with known vulnerabilities, such as buffer overflows. The process typically involves:
– Opening the application in OllyDbg and identifying vulnerable functions.
– Modifying the execution flow to exploit the vulnerability and gain access to unauthorized data.
"`markdown
# Code for Testing Buffer Overflow
"`c
void vulnerable_function(char *input) {
char buffer[64];
strcpy(buffer, input); // Vulnerable to buffer overflow
}
"`
"`
### 2.3 Advanced Features
#### 2.3.1 Conditional Breakpoints
You can set conditional breakpoints based on specific criteria. For instance, if you only want to break when a certain variable has a specific value:
"`assembly
; Setting a conditional breakpoint
00401123: cmp eax, 0xdeadbeef
00401126: je breakpoint_location
"`
#### 2.3.2 Patching Executables
With OllyDbg, you can make modifications to the binary directly in memory. This can be useful for changing program logic during testing:
1. Find the address of the instruction you want to modify.
2. Right-click and select `Binary > Modify`.
### 2.4 Detailed Technical Explanations
#### 2.4.1 The OllyDbg Interface
The OllyDbg interface consists of multiple panels including:
– **Disassembly**: Displays the assembly code of the binary being debugged.
– **Registers**: Shows the current values of CPU registers.
– **Stack**: Displays the current call stack.
– **Memory**: Provides access to the raw memory of the process being analyzed.
#### 2.4.2 Understanding Assembly Code
To effectively use OllyDbg, a basic understanding of assembly language is crucial. Here’s a quick breakdown:
– **MOV**: Copies data from one location to another.
– **CALL**: Calls a function.
– **RET**: Returns from a function.
– **JMP**: Unconditional jump to another instruction.
Familiarize yourself with these operations, as they are frequent in binary code analysis.
### External References
– [OllyDbg Official Website](https://www.ollydbg.de)
– [Malware Analysis Techniques](https://www.owasp.org/index.php/Malware_Analysis)
– [Understanding Assembly Language](https://www.learn-c.org/en/Assembly_Language)
—
This concludes our section on the installation and configuration of OllyDbg on Kali Linux, as well as its basic and advanced usage in penetration testing.
Made by pablo rotem / פבלו רותם