Erinevus lehekülje "Itx8071-task2" redaktsioonide vahel
| 48. rida: | 48. rida: | ||
* consider the use of contexts for memorizing suspicious hosts, | * consider the use of contexts for memorizing suspicious hosts, | ||
* consider the use of contexts for memorizing already observed network ports and user names, | * consider the use of contexts for memorizing already observed network ports and user names, | ||
| − | * all parts of the solution must be fully functional even when probing is conducted from several hosts in parallel (for example, contexts maintained by different counting operations must not interfere with each other). | + | * all parts of the solution must be fully functional even when port probing or user account probing is conducted from several hosts in parallel (for example, contexts maintained by different counting operations must not interfere with each other). |
Redaktsioon: 13. detsember 2018, kell 20:55
This homework assignment requires the knowledge from Modules 6 and 7.
Create SEC rules that accomplish the following event correlation task:
1) if netfilter firewall blocked packet events have been seen for the same host, so that the host has probed 5 distinct TCP and/or UDP ports within 2 minutes, memorize that host for the following 1 hour as suspicious host.
Note that ports must be distinguished not only by port number, but transport protocol should also be considered (for example, ports 53/tcp and 53/udp must be regarded different).
For example, if the following events appear for host 192.168.56.1, this host should be memorized as suspicious, since it has probed 5 distinct ports 161/udp, 21/tcp, 23/tcp, 25/tcp, and 123/udp within 2 minutes:
Nov 7 14:14:48 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=32 TOS=0x00 PREC=0x00 TTL=64 ID=32591 DF PROTO=UDP SPT=46062 DPT=161 LEN=12 Nov 7 14:15:06 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=32 TOS=0x00 PREC=0x00 TTL=64 ID=34001 DF PROTO=UDP SPT=37036 DPT=161 LEN=12 Nov 7 14:15:18 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=37323 DF PROTO=TCP SPT=38954 DPT=21 WINDOW=29200 RES=0x00 SYN URGP=0 Nov 7 14:15:22 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=3465 DF PROTO=TCP SPT=51418 DPT=23 WINDOW=29200 RES=0x00 SYN URGP=0 Nov 7 14:15:23 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=3466 DF PROTO=TCP SPT=51418 DPT=23 WINDOW=29200 RES=0x00 SYN URGP=0 Nov 7 14:16:01 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=60601 DF PROTO=TCP SPT=50250 DPT=25 WINDOW=29200 RES=0x00 SYN URGP=0 Nov 7 14:16:02 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=60602 DF PROTO=TCP SPT=50250 DPT=25 WINDOW=29200 RES=0x00 SYN URGP=0 Nov 7 14:16:46 localhost kernel: iptables: IN=enp0s8 OUT= MAC=08:00:27:ce:72:9a:0a:00:27:00:00:00:08:00 SRC=192.168.56.1 DST=192.168.56.103 LEN=32 TOS=0x00 PREC=0x00 TTL=64 ID=39224 DF PROTO=UDP SPT=41553 DPT=123 LEN=12
2) if a host has been previously memorized as suspicious, and from this host 3 distinct non-existing user accounts are probed over SSH within 1 minute, send an alert e-mail to the local root user (root@localhost). After e-mail has been sent, disable all further alert e-mails for the same host for the following 3 hours.
For example, suppose the host 192.168.57.13 has been memorized as suspicious less than 1 hour ago, and the following events are observed:
Nov 7 14:36:09 localhost sshd[1336]: Failed none for invalid user admin from 192.168.57.13 port 36404 ssh2 Nov 7 14:36:10 localhost sshd[1336]: Failed password for invalid user admin from 192.168.57.13 port 36404 ssh2 Nov 7 14:36:16 localhost sshd[1338]: Failed password for invalid user oracle from 192.168.57.13 port 36406 ssh2 Nov 7 14:36:18 localhost sshd[1338]: Failed password for invalid user oracle from 192.168.57.13 port 36406 ssh2 Nov 7 14:36:21 localhost sshd[1338]: Failed password for invalid user oracle from 192.168.57.13 port 36406 ssh2 Nov 7 14:36:50 localhost sshd[1340]: Failed none for invalid user sybase from 192.168.57.13 port 36412 ssh2
Since 3 distinct non-existing user accounts admin, oracle, and sybase have been probed over SSH from suspicious host 192.168.57.13 within 1 minute, an alert message about this host (e.g., "SSH probing of non-existing user accounts from 192.168.57.13") must be sent to root@localhost via e-mail. Also, further alerting must be disabled for host 192.168.57.13 for 3 hours.
Some hints for accomplishing this assignment:
- consider the use of contexts for memorizing suspicious hosts,
- consider the use of contexts for memorizing already observed network ports and user names,
- all parts of the solution must be fully functional even when port probing or user account probing is conducted from several hosts in parallel (for example, contexts maintained by different counting operations must not interfere with each other).