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UNIX Postmortem. Mark Henman. Introduction. For most system administrators, there is no question that at some point at least one of their systems is going to be hijacked by someone else.
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UNIX Postmortem Mark Henman
Introduction For most system administrators, there is no question that at some point at least one of their systems is going to be hijacked by someone else. This presentation should provide enough information to help an administrator quickly and successfully recover from an attack.
Discovery • Realize that you’ve been hacked • Tools • Observation
Realize that you’ve been hacked • Crackers use to make themselves known quickly • Web site defacing • Today’s crackers hide • Hijacked machine market
Tools • seccheck • chkrootkit • Tripwire • Snort • Use more than one form of intrusion detection. • Watch for intruders inside and out.
Trust Nothing! • Files may have been replaced • Binaries • Shared Libraries • Kernel
Trust Nothing! • Disconnect the Network • Shutdown the system • Boot from a trusted hard drive • Mount compromised file systems without execute permissions
Examining The System • Log Files • Changed system executables • Shared libraries • Viewed files • Back doors • Other network accessible systems
System Restoration • Backup user data • Check for alterations • Re-install the Operating System • Restore user data
Follow-up • Harden the system against attack • Check for abnormal behavior • Bring the system back into service • Monitor the log files
Conclusion • Don’t panic! • Isolate quickly • Examine slowly and carefully • Protect the system from a repeat attack
Where to Get More Information • www.snort.org • www.tripwire.org • www.chkrootkit.org • www.sans.org