Security on phinguin123 http://phinguin.dev/categories/security/ Recent content in Security on phinguin123 Hugo en-us 2026 phinguin Tue, 03 Nov 2026 21:00:00 +0900 리눅스 커널 Use-After-Cleanup (UAC) 취약점과 UACatcher 정리 http://phinguin.dev/blog/kernel-uac-vulnerability-uacatcher-breakdown/ Tue, 03 Nov 2026 21:00:00 +0900 http://phinguin.dev/blog/kernel-uac-vulnerability-uacatcher-breakdown/ 리눅스 커널의 cleanup 루틴과 syscall 루틴의 방향 차이로 생기는 Use-After-Cleanup 취약점, dPair 개념, 그리고 pty를 이용한 exploit 가능성 정리. Pen-Testing My Own Upload Endpoint http://phinguin.dev/blog/accidentally-safe-isnt-safe/ Wed, 01 Jul 2026 20:01:00 +0900 http://phinguin.dev/blog/accidentally-safe-isnt-safe/ Tried to path-traverse my own homework upload API. It held up, but only because of a timestamp prefix I never meant as a security thing. I Pulled /etc/passwd Off My Own Server http://phinguin.dev/blog/reading-my-own-etc-passwd/ Mon, 29 Jun 2026 20:48:00 +0900 http://phinguin.dev/blog/reading-my-own-etc-passwd/ An nginx 400 felt like a fix. send_from_directory felt like a fix. Then a different endpoint handed me /etc/passwd, and the real question was how bad that actually is. What the Four SSL Files Actually Do http://phinguin.dev/blog/what-ssl-certificate-files-actually-do/ Thu, 26 Mar 2026 12:12:00 +0900 http://phinguin.dev/blog/what-ssl-certificate-files-actually-do/ cert.crt, chain_cert.crt, root_cert.crt and a .key. I’d installed them a dozen times without knowing why there were four, so I finally sat down and worked it out on my own server.