(select concat(0x3a,char(64),char(52),char(51),char(55),char(48),char(49),@@version,char(64),char(49),char(48),char(55),char(51),char(52)))

Here’s what that SQL expression does and what it would output if it were executed in a vulnerable context.

What the payload does

• It builds a string with concatenation (CONCAT) from a mix of:
  • 0x3a → ":" (hex literal)
  • char(64) → "@"
  • char(52), char(51), char(55), char(48), char(49) → "43701"
  • @@version → the MySQL server version (e.g., "8.0.34")
  • another char(64) → "@"
  • then char(49), char(48), char(55), char(51), char(52) → "10734"

Putting that together, the resulting string is: ":" + "@" + "43701" + + "@" + "10734" i.e. a string of the form: :@43701@10734

Example

• If the MySQL server version is 8.0.34, the output would look like: :@437018.0.34@10734

Why this is used

• It’s a classic SQL injection payload designed to exfiltrate information (the server version) by constructing a visible string. The obfuscation (hex/char() functions) can help bypass simple filters.

Safety and exam context

• Do not run injection payloads against systems you do not own or have explicit permission to test.
• In an exam or lab, you’re likely studying how such payloads can leak info and how to defend against them.

Defensive measures (how to protect against this kind of attack)

• Use parameterized queries (prepared statements) for all user input.
• Avoid dynamic SQL that concatenates user input into queries.
• Apply input validation and strict whitelisting where possible.
• Limit database user privileges (least privilege); avoid exposing version or other sensitive data through normal queries.
• Disable verbose error messages and filter/normalize output to prevent leaking server information.
• Keep database software up to date and consider a Web Application Firewall (WAF) or database firewall rules to detect common injection patterns.

If you’d like, I can:

• Decode similar payloads step-by-step for practice.
• Show examples of how to write safe queries in a language you’re studying (e.g., Python with parameterized queries, PHP PDO, Java JDBC).
• Create a small lab exercise to demonstrate detection and prevention of this kind of injection.