Beyond the Pentest: How C2, Internal Pivoting, and Data Exfiltration Show True Risk

1. Beyond the Pentest How C2, Internal Pivoting, and Data Exﬁltration Show True Risk Beau Bullock

2. Beyond the Pentest What does a standard internal network pentest already cover? Port scans Vulnerability scanning Manual validation Provide recommendations

3. What is Wrong With This Attackers don’t vulnerability scan - too noisy Misses some very critical vulnerabilities Doesn’t account for domain systems already compromised

4. whoami Beau Bullock Pentester at Black Hills Information Security Host of Hack Naked TV Previously an enterprise defender OSCP, GXPN, GPEN, GCIH, GCFA, OSWP and GSEC

5. What Are We Missing Three major things Command and Control Internal Pivoting Data Exﬁltration

6. How Do We Test These Start with the basics Standard domain user account Lowest level of access typically provisioned Standard system build Anyone on leave? Steal their system Standard network access

7. Command and Control

8. Command and Control Three focus areas Payload delivery Email, web, etc. Client-based protections AV, application whitelisting, HIDS, etc. Network-based protections Egress filtering, IDS/IPS, inline payload detonation

9. C2: Payload Delivery What can be emailed to your employees? Executable PDF Word DOC or XLS w/ macro Batch ﬁle Encrypted ZIP Extensionless ﬁles?

10. C2: Payload Delivery Protip: Many webmail services scan attachments for malware Some don’t allow EXE’s altogether Yahoo’s MTA does not scan, and allows EXE’s Use a third-party mail client to send through Yahoo

11. C2: Payload Delivery What can be downloaded? How about browser or Java or Adobe exploits? Are users allowed to insert USB drives?

12. C2: Client-Based Protections Did anything detect the payload after entry? Anti-Virus Application whitelisting SIEM alerts

13. C2: Client-Based Protections Payload types Non-encoded EXE Encoded EXE ShellCode injection Word Doc w/ macro Software exploit Physical access (rubber ducky)

14. C2: Client-Based Protections Bypassing Client-based protections Veil-Evasion Framework for creating custom malware PowerSploit Shellcode injection directly into memory Obfuscation

15. C2: Network-Based Protections Was the C2 channel detected? Firewall block IDS/IPS detection Inline Detonation

16. C2: Network-Based Protections What does an outbound portscan reveal? open.zorinaq.com Weak egress ﬁltering provides more legroom for C2 DLP might miss items not sent over standard ports

17. C2: Some Typical C2 Channels Standard TCP HTTP/HTTPS DNS ICMP

18. C2: C2 Through A Web Proxy Meterpreter Reverse_https Uses proxy settings on system PowerShell Empire!!! Same as above but in PowerShell Appears as web trafﬁc through your web proxy

19. C2: C2 Over Social Media Can your users get to any social media sites? Twittor - Uses Twitter direct messages as a C2 channel GCAT - Uses Gmail as a C2 channel Sneaky-Creeper - Uses Twitter, Tumblr, and Soundcloud as a C2 channel

20. C2: C2 over DNS DNScat Tunnels trafﬁc through DNS requests C2 channel through NS Records C2 even with EVERY port blocked outbound from the client https://github.com/iagox86/dnscat2

21. C2: C2 over ICMP Invoke-PowerShellICMP Tunnels trafﬁc through ICMP echo-requests and echo-replys ICMP is commonly allowed through ﬁrewalls https://github.com/samratashok/nishang/tree/master/Shells

22. Internal Pivoting

23. Internal Pivoting Use built-in tools as a low level user to compromise a network No vuln scans needed Less noise Escalate privileges; locate sensitive data

24. Pivot: GPP Passwords May 13, 2014 – MS14-025 Passwords of accounts set by GPP are trivially decrypted! …by ANY authenticated user on the domain Located in groups.xml ﬁles on SYSVOL https://msdn.microsoft.com/en-us/library/2c15cbf0-f086-4c74-8b70-1f2fa45dd4be.aspx http://blogs.technet.com/b/srd/archive/2014/05/13/ms14-025-an-update-for-group-policy-preferences.aspx https://dirteam.com/sander/2014/05/23/security-thoughts-passwords-in-group-policy-preferences-cve-2014-1812/

25. Pivot: GPP Passwords First thing I check for on an internal assessment Almost always ﬁnd an admin password here Find it with: PowerSploit - Get- GPPPassword Metasploit GPP Module Or… C:>findstr /S cpassword %logonserver%sysvol*.xml

26. Pivot: Privilege Escalation Local privilege escalation Are we already a local admin? PowerUp Invoke-AllChecks looks for potential privilege escalation vectors http://www.verisgroup.com/2014/06/17/powerup-usage/

27. Pivot: Misconﬁgured Systems Occasionally, admins get lazy… and do things like add “Domain Users” group to the “Local Administrators” group

28. Pivot: Misconﬁgured Systems This means EVERY domain user is now is an administrator of that system Veil-PowerView Find-LocalAdminAccess Veil-PowerView Invoke-ShareFinder http://www.harmj0y.net/blog/penetesting/ﬁnding-local-admin-with-the-veil-framework/

29. Pivot: Password Spraying Domain locks out accounts after a certain number of failed logins Can’t brute force Solution: Try a number of passwords less than the domain lockout policy against EVERY account in the domain

30. Pivot: Password Spraying Lockout Policy = Threshold of ﬁve Let’s try one password across every account What passwords do we try? Password123 Companyname123 SeasonYear C:>@FOR /F %n in (users.txt) DO @FOR /F %p in (pass.txt) DO @net use DOMAINCONTROLLER IPC$ /user:DOMAIN%n %p 1>NUL 2>&1 && @echo [*] %n:%p && @net use /delete DOMAINCONTROLLERIPC$ > NUL

31. Pivot: Password Spraying

32. Pivot: LLMNR & NBTNS Poison LLMNR = Link-Local Multicast Name Resolution NBT-NS = NetBIOS over TCP/IP Name Service Both help hosts identify each other when DNS fails

33. Pivot: LLMNR & NBTNS Poison http://www.sternsecurity.com/blog/local-network-attacks-llmnr-and-nbt-ns-poisoning

34. Pivot: LLMNR & NBTNS Poison SpiderLabs Responder Inveigh PowerShell Script The result is that we obtain NTLM challenge/response hashes Crack hashes https://www.trustwave.com/Resources/SpiderLabs-Blog/Introducing-Responder-1-0/

35. Sensitive Data Hunt

36. Sensitive Data: Info Disclosure on Shares Sensitive files on shares? Find them with PowerView ShareFinder then FileFinder FileFinder will find files with the following strings in their title: ‘*pass*’, ‘*sensitive*’, ‘*admin*’, ‘*secret*’, ‘*login*’, ‘*unattend*.xml’, ‘*.vmdk’, ‘*creds*’, or ‘*credential*’

37. Sensitive Data: Locate RDP Jump Hosts Where are users RDP’ing to? Can provide insight into where critical systems are Get-NetComputers | Get-NetRDPSessions | Export- Csv –NoTypeInformation rdpsessions.csv http://www.harmj0y.net/blog/powershell/powerquinsta/

38. Sensitive Data: Virtualization Hypervisors

39. Data Exﬁltration

40. Data Exﬁltration What are organizations concerned about leaving their networks? PCI data Patient health information Personally Identifying Information Intellectual property

41. Data Exﬁltration How can attackers get data out of your network? Email Web Access USB Drive Photo

42. Data Exﬁl: Email For email is DLP being enforced on the following? Cleartext in email body Encoded in email body Attachments Optical Character Recognition

43. Data Exﬁl: Web Is all web trafﬁc subject to DLP inspection? Same types of tests as email are performed but tracking over standard and non-standard web ports

44. Data Exﬁl: USB Drives Are ﬁles allowed to be copied to a USB drive? Encryption DLP Blocked completely

45. Putting It All Together

46. Attack Scenario Target Organization Setup Firewall only allows outbound trafﬁc through web proxy AV up to date on clients Email gateway allows Doc ﬁles Local Administrator account is widespread with same credentials

47. Attack Scenario Phishing email is crafted with Word doc attachment Word doc is weaponized with a Macro Email is sent to target employee

48. Attack Scenario Employee opens email Downloads attached .doc Enables content Macro runs PowerSploit PowerShell script to inject Meterpreter Reverse_https into memory Meterpreter C2 channel is established

49. Attack Scenario Password spray from the command line Spring2016? Run Find-LocalAdminAccess to ﬁnd where the users are local admin Pivot using psexec

50. Attack Scenario Attacker dumps local user hashes (including local admin) Local administrator credential is not randomized Using PowerView UserHunter the attacker ﬁnds where Domain Admins are located

51. Attack Scenario Attacker pivots to DA workstation Runs Mimikatz to dump creds from memory Locates sensitive data with PowerView ShareFinder Exﬁls data

52. Summary

53. Summary What are the beneﬁts of this style of testing? Real test of detection and incident response Shows how an attacker can go from low access to owning the environment Shows true risk to the organization

54. Thank You! beau@blackhillsinfosec.com beau@dafthack.com @dafthack

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