Câu 172: 312-49V10: Computer Hacking Forensic Investigator

Study the log given below and answer the following question:Apr 24 14:46:46 [4663]: spp_portscan: portscan detected from 194.222.156.169Apr 24 14:46:46 [4663]: IDS27/FIN Scan: 194.222.156.169:56693 -> 172.16.1.107:482Apr 24 18:01:05 [4663]: IDS/DNS-version-query: 212.244.97.121:3485 -> 172.16.1.107:53Apr 24 19:04:01 [4663]: IDS213/ftp-passwd-retrieval: 194.222.156.169:1425 -> 172.16.1.107:21Apr 25 08:02:41 [5875]: spp_portscan: PORTSCAN DETECTED from 24.9.255.53Apr 25 02:08:07 [5875]: IDS277/DNS-version-query: 63.226.81.13:4499 -> 172.16.1.107:53Apr 25 02:08:07 [5875]: IDS277/DNS-version-query: 63.226.81.13:4630 -> 172.16.1.101:53Apr 25 02:38:17 [5875]: IDS/RPC-rpcinfo-query: 212.251.1.94:642 -> 172.16.1.107:111Apr 25 19:37:32 [5875]: IDS230/web-cgi-space-wildcard: 198.173.35.164:4221 -> 172.16.1.107:80Apr 26 05:45:12 [6283]: IDS212/dns-zone-transfer: 38.31.107.87:2291 -> 172.16.1.101:53Apr 26 06:43:05 [6283]: IDS181/nops-x86: 63.226.81.13:1351 -> 172.16.1.107:53Apr 26 06:44:25 victim7 PAM_pwdb[12509]: (login) session opened for user simple by (uid=0)Apr 26 06:44:36 victim7 PAM_pwdb[12521]: (su) session opened for user simon by simple(uid=506)Apr 26 06:45:34 [6283]: IDS175/socks-probe: 24.112.167.35:20 -> 172.16.1.107:1080Apr 26 06:52:10 [6283]: IDS127/telnet-login-incorrect: 172.16.1.107:23 -> 213.28.22.189:4558Precautionary measures to prevent this attack would include writing firewall rules. Of these firewall rules, which among the following would be appropriate?

1. A. Disallow UDP53 in from outside to DNS server — đáp án hiện tại
2. B. Allow UDP53 in from DNS server to outside
3. C. Disallow TCP53 in from secondaries or ISP server to DNS server
4. D. Block all UDP traffic