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Compromising a Unix Host

An Introduction to Tools and Techniques. -Mike Sconzo. Compromising a Unix Host. Important Things. Information Gathering Techniques Active, passive Tools Nmap, ping, mtr, traceroute, dig, ettercap, Xprobe2, p0f, Nessus, tcpdump, Dsniff Types of Attacks Basic Exploit What to look for.

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Compromising a Unix Host

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  1. An Introduction to Tools and Techniques. -Mike Sconzo Compromising a Unix Host

  2. Important Things • Information Gathering • Techniques • Active, passive • Tools • Nmap, ping, mtr, traceroute, dig, ettercap, Xprobe2, p0f, Nessus, tcpdump, Dsniff • Types of Attacks • Basic Exploit • What to look for

  3. Active vs. Passive • Passive • Harder for people to detect (especially if truly passive) • Sometimes less accurate results • Tools • Tcpdump, p0f, dsniff, ettercap (sometimes), ethereal • Active • Easy to detect, especially if used in 'default' configuration, can usually make it 'harder' to detect • Usually more accurate • Tools • Ping, traceroute, Xprobe2, Nmap, ettercap, Nessus, MTR

  4. Passive Tools • Tcpdump • Sniffer, easy to detect if not run correctly • Effective and easy to use • p0f • Passive OS detection, harder to detect. • ettercap • Swiss army knife of network hijacking! • Many of the features of Dsniff, but expanded, can MiTM some services, and generally cause problems :) • Dsniff • Tool/suite of tools for password recon, and other things

  5. Active Tools • Ping • Check to see if a host is alive ... other uses? • Traceroute • Find the path to a host ... other uses/benefits of knowing path? • MTR • Ping + Traceroute! • Xprobe2 • Active OS fingerprinting using ICMP • Nmap • Active OS fingerprinting, open ports, service versioning and more!

  6. Active Tools continued • ettercap • Arp spoof (many uses), passive OS fingerprinting, MiTM, kill connections (similar to hunt), and ... you can write your own plugins! • Nessus • Vulnerability (!!) scanner, expandable, 'new hotness'

  7. Types of Attacks • Man in The Middle (MiTM) • Sit between target and victim • For some defination of “between” • Denial of Service (DoS) • Deny access to the box/service • Social Engr. • Attack the weakest link • 'spliot • Buffer overflow, format string vuln etc...?

  8. MiTM • Multiple ways/services to attack • SSH (example) • Ssh mitm v2 – proxy • v1 – not cryptographically secure! • Maybe force v1 connection? • Arp spoof, dns spoof • Other ideas?

  9. DoS • Deny access to something • Login Host (example) • ICMP flood (humm...what can do this?) • SYN flood (use up available 'connections') • Lots more! • Considered a 'lame' attack by itself • But, serves a purpose ....

  10. Social Engr. • Go after people • Why guess the password when somebody could tell it to you? • Get somebody to install a vulnerable version of a program. Because a sys-admins job is giving his users something to use. • Could be the latest version of something, but if you did a code audit, you may know something secret (aka 0-day).

  11. 'sploits • Attacks in a can • Easy to use • Easy to find • Used by the lowest common denominator! • Effective on systems that have not been patched/configured correctly • Why do the hard stuff, if the low hanging fruit is a knee level? • Excellent way to learn

  12. Basic Attack • We have gathered some information • passive/active • Maybe we did a code audit, and found a 0-day to get on the box, or perhaps we downloaded something • But only got 'user' privs. Bummer, we want r00t! • Now what? Time to find a local exploit! • What to look at? • Kernel, daemons, set-uid programs, why? • Escalate privs • Cover your tracks • Wipe logs, fun with tripwire!

  13. How do we get back in? • Rootkit? • Lots to choose from • Unfortunately most are easily detectable • Custom write one, maybe • Rogue accounts • Good choice, but easily detectable • Why not an account that's already on the machine with sudo? • Simple Backdoor • NetCat (nc)

  14. Play Time!

  15. References • http://www.insecure.org/ • http://ettercap.sourceforge.net/ • http://www.sys-security.com/html/projects/X.html • http://lcamtuf.coredump.cx/p0f.tgz • http://www.nessus.org/ • http://www.bitwizard.nl/mtr/

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