CVE-2017-6369

What it actually does

Insufficient validation in the UDF subsystem permits remote authenticated users to invoke the 'system' entrypoint from fbudf.so, resulting in arbitrary operating system command execution under the database process privileges.

Why it matters to the business

Attackers who already possess database credentials can execute commands on the server hosting the database, enabling data exfiltration, ransomware deployment, or full host compromise; organizations still running unpatched Firebird 2.5.x or 3.0.x face elevated risk of prolonged exposure.

How an attack unfolds

An attacker obtains valid database credentials, connects to the Firebird instance, and issues a crafted query that registers and calls the 'system' function from the fbudf library to run operating system commands.

How to fix it

Upgrade to a fixed release containing commit 19b1a66671449091b87a5f8641b93c86f9f79e34 or later; apply versions 2.5.7 or 3.0.2 and higher, disable unused UDF libraries, and restrict database accounts to least-privilege roles.

How to confirm the fix worked

Confirm the installed Firebird version is 2.5.7 or 3.0.2 or newer; attempt a test UDF call to the 'system' entrypoint from a non-privileged account and verify it is rejected.

Typical attack path

1. Obtain valid database user credentials
2. Connect to the Firebird server over the network
3. Register or reference the fbudf library
4. Invoke the 'system' entrypoint with attacker-supplied commands
5. Execute arbitrary OS commands and establish persistence or exfiltrate data

How to detect it

Review Firebird server logs and operating system process creation events for unexpected invocations of fbudf.so or the 'system' entrypoint; inspect database audit trails for unusual UDF registration or execution patterns.

• fbudf.so
• system entrypoint
• UDF.*system

What your security team should do

• Immediately upgrade all Firebird instances to a fixed version
• Audit and restrict UDF library loading and database user privileges
• Monitor for any remaining unpatched instances given the 2017 disclosure date
• Review network exposure of database ports and enforce strong authentication