Auditd : Add Audit Rules2023/07/13 |
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It's possible to add your own Audit rules like follows.
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| [1] | For example, Configure Audit rule that records writing and attributes change for [/etc/hosts]. |
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# display current rules (no rules by default like follows) root@dlp:~# auditctl -l No rules # -p [r|w|x|a] : specify target action for Audit # r=read, w=write, x=execute, a=attributes # -k [words] : set keys for searching logs root@dlp:~# auditctl -w /etc/hosts -p wa -k hosts_change root@dlp:~# auditctl -l -w /etc/hosts -p wa -k hosts_change |
| [2] | When some actions are set and it is detected by new Audit rules, Audit logs are recorded like follows. |
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root@dlp:~# ausearch -k hosts_change | aureport -f -i =============================================== # date time file syscall success exe auid event =============================================== 1. 07/12/2023 21:18:16 /etc/hosts~ rename yes /usr/bin/vim.basic root 301 2. 07/12/2023 21:18:16 /etc/hosts openat yes /usr/bin/vim.basic root 302 3. 07/12/2023 21:18:16 (null) fchmod yes /usr/bin/vim.basic root 303 4. 07/12/2023 21:18:16 /etc/hosts setxattr yes /usr/bin/vim.basic root 304 5. 07/12/2023 21:18:27 /etc/hosts~ rename yes /usr/bin/vim.basic root 305 6. 07/12/2023 21:18:27 /etc/hosts openat yes /usr/bin/vim.basic root 306 7. 07/12/2023 21:18:27 (null) fchmod yes /usr/bin/vim.basic root 307 8. 07/12/2023 21:18:27 /etc/hosts setxattr yes /usr/bin/vim.basic root 308 9. 07/12/2023 21:19:19 /etc/hosts~ rename yes /usr/bin/vim.basic debian 339 10. 07/12/2023 21:19:19 /etc/hosts openat yes /usr/bin/vim.basic debian 340 11. 07/12/2023 21:19:19 (null) fchmod yes /usr/bin/vim.basic debian 341 12. 07/12/2023 21:19:19 /etc/hosts setxattr yes /usr/bin/vim.basic debian 342 |
| [3] | Rules added by [auditctl] command are not kept after restarting System, so it needs to add them in a file under [/etc/audit/rules.d] if you'd like to keep persistently. It's OK to add rules to any file name you like under [/etc/audit/rules.d], but extension should be [.rules]. |
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# output current rules to [additional.rules] root@dlp:~# auditctl -l >> /etc/audit/rules.d/additional.rules |
| [4] | If you set a directory for Audit Target, all files are targeted recursively under the directory. |
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# set Audit rule (reading) to [/home/testdir/] root@dlp:~# auditctl -w /home/testdir/ -p r -k testdir_audit root@dlp:~# auditctl -l -w /etc/hosts -p wa -k hosts_change -w /home/testdir -p r -k testdir_audit # logs are recorded like follows root@dlp:~# ausearch -k testdir_audit | aureport -f -i File Report =============================================== # date time file syscall success exe auid event =============================================== 1. 07/12/2023 21:21:32 /home/testdir sendto yes /usr/sbin/auditctl root 52 2. 07/12/2023 21:22:40 /home/testdir/testfile.txt openat yes /usr/bin/vim.basic debian 83 3. 07/12/2023 21:22:40 /home/testdir/testfile.txt readlink no /usr/bin/vim.basic debian 84 4. 07/12/2023 21:22:40 /home/testdir/.testfile.txt.swp openat yes /usr/bin/vim.basic debian 85 5. 07/12/2023 21:22:40 /home/testdir/.testfile.txt.swx openat yes /usr/bin/vim.basic debian 86 6. 07/12/2023 21:22:40 /home/testdir/.testfile.txt.swp openat yes /usr/bin/vim.basic debian 87 7. 07/12/2023 21:22:40 /home/testdir/testfile.txt openat yes /usr/bin/vim.basic debian 88 8. 07/12/2023 21:22:44 /home/testdir/testfile.txt getxattr no /usr/bin/vim.basic debian 89 9. 07/12/2023 21:23:26 /home/testdir/test.txt openat yes /usr/bin/vim.basic bookworm 125 10. 07/12/2023 21:23:26 /home/testdir/test.txt openat yes /usr/bin/vim.basic bookworm 126 ..... ..... |
| [5] | For example, Set Audit rule that monitors files removed by users who has over UID 1000. |
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root@dlp:~#
auditctl -a always,exit -F arch=b64 -S unlink,unlinkat -F 'auid>=1000' -F 'auid!=-1' -F key=delete_audit root@dlp:~# auditctl -l -w /etc/hosts -p wa -k hosts_change -w /home/testdir -p r -k testdir_audit -a always,exit -F arch=b64 -S unlink,unlinkat -F auid>=1000 -F auid!=-1 -F key=delete_audit # logs are recorded like follows root@dlp:~# ausearch -k delete_audit | aureport -f -i File Report =============================================== # date time file syscall success exe auid event =============================================== 1. 07/12/2023 21:26:39 /run/user/1000/systemd/ unlink no /usr/lib/systemd/systemd debian 210 2. 07/12/2023 21:26:39 /run/user/1000/systemd/ unlink no /usr/lib/systemd/systemd debian 211 3. 07/12/2023 21:26:52 /home/testdir/test.txt unlinkat no /usr/bin/rm debian 233 4. 07/12/2023 21:27:12 /home/testdir/test.txt unlinkat yes /usr/bin/rm debian 239 5. 07/12/2023 21:27:32 /run/user/1000/systemd/units/invocation:dbus.socket unlink yes /usr/lib/systemd/systemd debian 269 6. 07/12/2023 21:27:32 init.scope unlinkat no /usr/lib/systemd/systemd debian 270 |
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