SQL Injection Testing Skill

Purpose

Validate SQL injection (including blind SQLi) by injecting SQL syntax into user-controlled inputs and observing: - Time-based delays (blind) - Error messages (error-based) - Boolean/content differences (blind) - Data extraction via UNION - Stacked queries where supported - Out-of-band interactions (DNS/HTTP callbacks) when infra allows

Vulnerability Types Covered

1. Time-Based Blind SQLi (CWE-89)

Inject time-delay functions and detect response latency.

Detection Methods: SLEEP(5), pg_sleep(5), WAITFOR DELAY '0:0:5', heavy functions (e.g., randomblob() for SQLite).

2. Boolean-Based Blind SQLi (CWE-89)

Inject true/false conditions and compare content/length/status.

Detection Methods: ' OR '1'='1 vs ' OR '1'='2, AND 1=1 vs AND 1=2.

3. Error-Based SQLi (CWE-89)

Trigger SQL parser errors and observe verbose error responses.

Detection Methods: stray quote/backtick, type-cast errors, extractvalue()/updatexml() (MySQL), CAST('a' AS INT) (PostgreSQL/MSSQL).

4. UNION-Based SQLi (CWE-89)

Use UNION to extract data when column counts align.

Detection Methods: UNION SELECT NULL,NULL, ORDER BY N probing for column count.

5. Stacked Queries (CWE-89)

Inject additional statements when DB/driver permits (e.g., MSSQL ; WAITFOR, PostgreSQL ; SELECT pg_sleep(5)).

6. Out-of-Band SQLi (CWE-89)

Detect DNS/HTTP callbacks via load_file(), xp_dirtree, or UTL_HTTP/UTL_INADDR when response-based detection is blocked (use only if callback infra is authorized).

7. ORM/Framework-Specific (CWE-564)

Hibernate/JPA or query-builder misuse leading to SQLi (parameter concatenation, unsafe createQuery).

Database-Specific Notes

Prerequisites

• Target reachable; SQL-backed functionality identified (endpoints, forms, headers, cookies, path params).
• If authentication required: test accounts available (low-priv + optional admin) or mark paths UNVALIDATED.
• Know (or infer) DB type to choose correct payloads; default to generic when unknown.
• VULNERABILITIES.json with suspected SQLi findings if provided.

Testing Methodology

Phase 1: Identify Injection Points

• URL params, POST bodies (JSON/form), headers, cookies, path segments.
• Look for string interpolation, query concatenation, ORM custom queries.

Phase 2: Establish Baseline

• Send a benign request; record status, content length, and response time.
• Note WAF/rate-limit behaviors.

Phase 3: Execute SQLi Tests

Time-Based (Blind):

payload = "123' OR SLEEP(5)--"
resp_time = send(payload)
if resp_time > baseline_time + 4.5:
    status = "VALIDATED"

Boolean-Based (Blind):

true_p = "123' OR '1'='1"
false_p = "123' OR '1'='2"
len_true = len(send(true_p).text)
len_false = len(send(false_p).text)
if abs(len_true - len_false) >= 50:
    status = "VALIDATED"

Error-Based:

payload = "123'"
resp = send(payload)
if any(err in resp.text.lower() for err in sql_errors):
    status = "VALIDATED"

UNION/Stacked Probing: - ORDER BY incrementally to find column count. - UNION SELECT NULL,... until count matches; watch for 200 vs 500. - For stacked-capable DBs: append ; SELECT pg_sleep(5) or ; WAITFOR DELAY '0:0:5'.

Out-of-Band (only if infra-approved): - Use controlled collaborator domain; record DNS/HTTP hits. - Stop if any unexpected external interaction occurs.

Phase 4: Classification Logic

Phase 5: Capture Evidence

Capture minimal structured evidence (redact PII/secrets, truncate to 8KB, hash full response). Include: - status, injection_type, cwe - Baseline request (url/method/status/time/hash) - Test request (url/method/status/time/hash, or collaborator hit details) - Payload used - Note if truncated and original size

Phase 6: Safety Rules

• Detection-only payloads; never destructive statements (DROP/DELETE/TRUNCATE/UPDATE/INSERT).
• Avoid data exfiltration; prefer boolean/time-based confirmation.
• Do not send OOB callbacks unless explicitly authorized.
• Respect rate limits; add delays between time-based probes.
• Redact credentials, tokens, and personal data in evidence.

Output Guidelines

• Keep responses concise (1-4 sentences).
• Include endpoint, payload, detection method, and impact.

Validated examples:

Time-based SQLi on /api/users?id - SLEEP(5) payload caused 5.1s delay (CWE-89). Evidence: path/to/evidence.json
Boolean-based SQLi on /products - response length differs for true vs false condition (CWE-89). Evidence: path/to/evidence.json
Error-based SQLi on /login - SQL syntax error returned to client (CWE-89). Evidence: path/to/evidence.json

Unvalidated example:

SQLi test incomplete on /reports - WAF blocked payloads (403). Evidence: path/to/evidence.json

CWE Mapping

Primary CWEs (DAST-testable): - CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') - CWE-564: SQL Injection: Hibernate (ORM-specific variant of CWE-89)

Parent/Related CWEs (context): - CWE-943: Improper Neutralization of Special Elements in Data Query Logic (parent class of CWE-89) - CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (grandparent) - CWE-20: Improper Input Validation (related - root cause)

Note: CWE-89 is ranked #2 in MITRE's 2025 CWE Top 25 Most Dangerous Software Weaknesses.

Notable CVEs (examples)

• CVE-2023-34362 (MOVEit Transfer): Pre-auth SQLi leading to mass data exfiltration; exploited by Cl0p ransomware.
• CVE-2024-27956 (WordPress Automatic Plugin): Unauthenticated SQLi allowing privilege escalation.
• CVE-2021-27065 (Microsoft Exchange ProxyLogon chain): Post-auth SQLi in OWA contributing to RCE chain.
• CVE-2019-2725 (Oracle WebLogic): Unauthenticated SQLi leading to RCE.
• CVE-2017-5638 (Apache Struts): OGNL injection (related pattern) leading to RCE via Content-Type header.
• CVE-2014-3704 (Drupal SA-CORE-2014-005): SQLi via Drupal 7/8 form API ("Drupalgeddon").

Safety Reminders

• ONLY test against user-approved targets; stop if production protections trigger.
• Do not log or store sensitive data; redact in evidence.
• Prefer parameterized queries and least-privileged DB accounts in mitigations.

Reference Implementations

• See reference/sql_payloads.py for SQLi payloads by DB and detection type.
• See reference/validate_sqli.py for a SQLi-focused validation flow (time/error/boolean/UNION/stacked).
• See examples.md for concrete SQLi scenarios and evidence formats.