bandit15->bandit16

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bandit15 link
https://overthewire.org/wargames/bandit/bandit16.html

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command to solve this level

이 레벨을 풀기 위해 알아야 하는 커맨드들은 아래와 같다.

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1. ssh :

• ssh 접속 커맨드
• ssh [id]@[url] -p[port]

2. telnet :

• text-based communication protocol
• telnet [hostname][port]

3. nc(Netcat) :

• networking utility for reading from and writing to network connections using TCP or UDP
• port scanning, file transfers, and creating network connections
• nc -vz [hostname][port]

4. openssl :

• A robust open-source toolkit for implementing SSL/TLS protocols.
• connects to a remote SSL/TLS server

5. s_client :

• A specific OpenSSL tool that connects to a remote SSL/TLS server and prints information about the SSL connection

6. nmap :

• open-source network scanning tool for discovering hosts and services on a computer network
• security auditing, and finding open ports
• nmap -p 1-1000 hostname (to scan ports 1 through 1000)

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문제 :

The password for the next level can be retrieved by submitting the password of the current level to port 30001 on localhost using SSL encryption.

문제 풀이 :

opeenssl s_client [옵션][호스트:포트]

openssl s_client -connect localhost:30001

위의 커맨드를 입력하면 아래와 같은 SSL/TLS 커넥션이 이뤄진다.

1. SSL/TLS Handshake:

Can't use SSL_get_servername
depth=0 CN = localhost
verify error:num=18:self-signed certificate
verify return:1
depth=0 CN = localhost
verify error:num=10:certificate has expired
notAfter=Jan 25 20:43:52 2024 GMT
verify return:1
depth=0 CN = localhost
notAfter=Jan 25 20:43:52 2024 GMT
verify return:1

2. Certificate:

-----BEGIN CERTIFICATE-----
MIIDCzCCAfOgAwIBAgIEXPQtNDANBgkqhkiG9w0BAQUFADAUMRIwEAYDVQQDDAls
b2NhbGhvc3QwHhcNMjQwMTI1MjA0MjUyWhcNMjQwMTI1MjA0MzUyWjAUMRIwEAYD
...
-----END CERTIFICATE-----

인증서를 받는다.

3. SSL/TLS Session Information:

SSL handshake has read 1339 bytes and written 373 bytes
Verification error: certificate has expired

몇 바이트를 읽고 썼는지 확인

이후 현재 단계 비밀번호를 입력 하면 다음 단계로 넘어갈 수 있다.

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REFERENCE

[1] https://overthewire.org/wargames/bandit/bandit16.html
[2] https://www.cloudflare.com/ko-kr/learning/ssl/what-happens-in-a-tls-handshake/
[3] https://m.blog.naver.com/alice_k106/221468341565