Enhancing Server Security: Practical Tips for Administrators

1. Security for Administrators Presented by: Greg SmithPacsec.jp2004

2. Introduction • Who am I? • Who do I work for, and what is my job? • Why I am talking about this?

3. Who am I? • Greg Smith • Using UNIX based operating systems for 8 years • Administrator work for 5 years • Working with security off and on for 4 years.

4. Who Do I Work For,and What is My Job? • I work for Secured Infrastructure Design Corporation. • I am a Security Analyst, and Administrator for various BSD / Linux servers

5. Why I Am Talking About This? • I believe that administrators should be more concerned about the well being of their servers. • I want to try and share some of my basic views on security.

6. Overview • My Definition of security • Operating system level security • Security via log monitoring • Interactive security • Administrator security measures

7. My Definition of Security • Making intelligent choices • Being educated, and always learning • Perceptiveness • Adaptation • Care and attention

8. Operating System Level Security • Proper application management • Keeping proper tabs on users’ interactions with the operating system • Noticing inconsistencies between the administrator and the user logins • Noticing inconsistencies in the file systems

9. Proper Application Management

10. Keeping Proper Tabs On Users • Watch login times, if you know said user was not in the office at a particular time, but appears to be logged in, check the logs further to see what this user did • Watch your own logins, if you notice an inconsistency with administrator logins, this would also warrant digging further into the logs.

11. Noticing InconsistenciesIn The File Systems • Is a file moved, deleted, or copied somewhere else on the system, and you don’t remember doing it? • Are there symlinks from logs to /dev/null. • Are there extra directories created with files in them you have never seen? • Watch for differences in the file system from the last time you logged in.

12. Security via Logging • Don’t be afraid to use tools like sed, awk, uniq, sort, to better navigate. • Interpret the logs, look for inconsistencies • Apache logs; look for file transfers from personal directories • FTP logs; look for suspicious transfers • Look for SSH authentication errors

13. Using Text Parsing ToolsTo Make Life Easier • Examples here are all based off FreeBSD 4.9’s default logging system.

14. Interpret The Logs, Look For Inconsistencies • Examples of this, in cron, 1000 entries • sed s/[0-9]/#/g cron.ot | sort | uniq

15. Secure/Auth Log Analysis • There are similar lines, parse them out better using awk and grep.

16. Secure/Auth Log Analysis • cat auth.log | grep Failed | awk '{print $3" "$6" "$7" "$11" "$13}‘ • Using simple grep/awk, weeded out a lot of useless information.

17. Messages Log Analysis • There are similar lines, parse them out better with grep.

18. Messages Log Analysis • Using grep to parse better • Going even further • cat messages | grep root | grep BAD • With those simple instructions, your viewing time can be cut substantially.

19. More Security via Logging • Watch the last log, using the last command • The httpd-access and httpd-error log can be handy in tracing a possible compromise. Use the same methods as in the other examples to better parse the httpd logs.

20. More Security Via Logging • Monitor logs on a regular basis • Learn the logging system for the particular operating system at hand • To save time, skim logs looking for said inconsistencies; if found then probe deeper. • Watch for inconsistencies in log file sizes

21. Interactive Security • What do I consider interactive security? • Why would someone use this method?

22. What Do I ConsiderInteractive Security? • Perceptiveness. • Know your system. • Customize your server or workstation to better suit you. • Understand that proper mindset can increase security substantially.

23. Why Would Someone Use This Method? • Cut down on man-hours used maintaining systems; less time will have to be spent by administrators on tedious tasks. • Enhance knowledge about basic functions of the operating system. • Less stressful work environment.

24. Administrative Measures • If a server has been compromised, learn from this, and adapt accordingly. • Segregation • Common sense

25. Conclusions • Administrators work closest with the actual infrastructure that needs the most attention. • Better education of administrators could lead to less of a chance of being compromised.

26. Questions? Special Thanks to: Richard S. Keirstead Lars Maul Steve Manzuik