That string is a SQL-injection style payload. Briefly:
- ' is the HTML entity for a single quote, so the payload reads something like:
chr6jTEt')) OR 717=(SELECT 717 FROM PG_SLEEP(15))--
- Intent: close a string/parenthesis, then use a boolean/time-based test (PG_SLEEP(15)) to delay the DB response by 15 seconds if the injected clause is evaluated — a common time-based blind SQL injection technique. The trailing -- comments out the rest of the original query.
I won’t help craft exploits, but here’s how to understand, detect, and mitigate this kind of attack safely.
What it does (high level)
- Causes the database to sleep/delay if the injected condition is executed, revealing that arbitrary SQL can be injected.
- Attackers use time delays to infer true/false conditions where direct output is not available.
How to detect attempts
- Repeated requests that increase response time by a consistent amount (e.g., +15s).
- Requests containing patterns like unescaped quotes, SQL keywords, or DB function names in parameters.
- Web/app server logs showing slow queries; DB logs showing long-running statements.
- WAF/IDS alerts on SQL-like payloads or comment markers (--) in parameters.
Mitigations (practical and effective)
Use parameterized queries / prepared statements (do not concatenate user input into SQL).
- Example (Python + psycopg2):
cur.execute("SELECT id, name FROM users WHERE username = %s", (username_input,))
- Example (Java + JDBC):
PreparedStatement ps = conn.prepareStatement("SELECT id FROM users WHERE email = ?");
ps.setString(1, emailInput);
ps.executeQuery();
Apply input validation/whitelisting:
- Validate format/length and restrict characters where applicable (e.g., usernames, IDs).
- Prefer whitelist rules over blacklists.
Principle of least privilege:
- Use DB accounts with only the necessary permissions. Don’t use a superuser for the application connection.
DB and session-level limits:
- Configure statement_timeout in PostgreSQL to bound how long a query can run:
SET statement_timeout = '5s'; -- per session
Or set for a role: ALTER ROLE myapp SET statement_timeout = '5000';
- Use connection timeouts and max statement execution times in your DB driver.
Escape/encode output and handle errors securely:
- Avoid returning raw DB error messages to users. Log detailed errors internally.
Use higher-level protections:
- Web Application Firewall (WAF) to block obvious SQLi patterns and rate-limit suspicious traffic.
- Parameterized ORM usage instead of manual SQL where possible.
Monitor and alert:
- Alert on spikes of slow queries, increased error rates, or repeated suspicious parameter patterns.
Safe testing guidance
- Only test against systems you own or have explicit permission to test.
- Use a staging/test environment that mirrors production for security testing.
- For authorized tests, use professional tools and follow a responsible disclosure process.
If you want, tell me:
- What language/framework and DB driver you’re using and I can show a short secure-coding example tailored to that environment.
- Whether you want help configuring Postgres statement_timeout for your app (include how you connect).