// 02_SECURITY
Tracing the Payload
Last week, we detected an anomaly in the authentication service. The signature verification was being bypassed by a clever manipulation of the JSON structure.
The Incident Logs
Scanning the logs revealed a pattern. The attacker was injecting null bytes into the JWT header.
root@server:~# tail -f /var/log/auth.log | grep "WARN"
[10:42:01] WARN: Invalid header byte at pos 44
[10:42:05] WARN: Payload mismatch signature
[10:42:09] CRITICAL: Admin privilege escalation detected from IP 192.168.x.x
[10:42:10] SYSTEM LOCKDOWN INITIATED...
[10:42:05] WARN: Payload mismatch signature
[10:42:09] CRITICAL: Admin privilege escalation detected from IP 192.168.x.x
[10:42:10] SYSTEM LOCKDOWN INITIATED...
root@server:~# _
The Exploit
The parser stopped reading the string at the null byte, but the signature verifier read the whole buffer. This created a discrepancy between what was validated and what was executed.
PATCH APPLIED: We now explicitly reject control characters in the header parsing stage before signature validation.