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What is Enumeration?

Enumerating slides (c) 2012 by Richard Newman based on Hacking Exposed 7 by McClure, Scambray, and Kurtz. What is Enumeration?. How does it differ from footprinting and scanning? Footprinting did not necessarily attempt to access the target system(s) directly

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What is Enumeration?

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  1. Enumeratingslides (c) 2012 by Richard Newmanbased on Hacking Exposed 7 by McClure, Scambray, and Kurtz

  2. What is Enumeration? How does it differ from footprinting and scanning? • Footprinting did not necessarily attempt to access the target system(s) directly • Scanning involved transient contact • Enumeration involves establishing connections and directed queries Information typically gathered • User account names (for password attacks) • Misconfigured shared resources • Software version and patch state (for known vulnerabilities) Detailed examination of target systems Platform specific – how you interact depends on target service/system

  3. Service Fingerprinting Automated method • Easy to use, use likely to increase • Generates a lot of traffic – likely to be noticed • Takes significant time Nmap Version Scanning • Popularity=9; Simplicity=8; Impact=3; Risk Rating=7 • Use -sV switch • Can find “hidden” services (use same port as other service) Amap Version Scanning (thc.org/thc-amap/) • Popularity=9; Simplicity=8; Impact=3; Risk Rating=7 • Older than nmap • Uses different patterns, so gives a second opinion

  4. Vulnerability Scanners - 1 Automated VS tools – Use when stealth not required • Know defender is not monitoring • Moving too fast to care Countermeasures • Keep system patched • Do your own scans • IDS – detect (pretty noisy) • IPS – prevent (slow down attacks to discourage, delay attacker)

  5. Vulnerability Scanners - 2 Nessus Scanning (nessus.org/products/nessus) Popularity=9; Simplicity=9; Impact=6; Risk Rating=8 • Easy to use GUI • Kept up to date • Optimized performance • Client ported to iPhone and Android • Extendable with user-developed custom plug-ins • Nessus Attack Scripting Language (NASL) • Open source version OpenVAS (openvas.org) is free

  6. Vulnerability Scanners - 3 Nmap Scanning Engine (NSE) Scanning Popularity=7; Simplicity=6; Impact=5; Risk Rating=6 • Extendable with user-developed scripts • Lua interpreted language • Intended for specific probing • - - script or -sC options to run scripts

  7. Basic Banner Grabbing Popularity=5; Simplicity=9; Impact=1; Risk Rating=5 telnet • Ascii-based interactive session client • Can use to connect to many servers (ASCII-based) netcat • “TCP/IP Swiss army knife” • Allows file input for tedious probes Countermeasures • Shut down unnecessary services • Restrict access to services • Disable banner display (vendor dependent) • Do your own checks

  8. Common Network Services - 1 - FTP - Telnet - SMTP - DNS - TFTP - Finger - HTTP - MSRPC - NetBIOS Name Service - SMB Null Session

  9. Common Network Services - 2 - SNMP - BGP - Active Directory LDAP - Unix RPC - rwho, rusers - NIS - SQL Resolution Service - Oracle TNS - NFS - IPSec/IKE

  10. FTP Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 - File Transfer Protocol – TCP port 21 • Less used now • Allows upload of (malicious) files • Often allows anonymous access using any email address • Get banner • Determine access - Countermeasures • Turn off • Secure FTP (SFTP) uses SSH • FTP Secure (FTPS) uses SSL • HTTP for public information access

  11. Telnet Enumeration Popularity=4; Simplicity=9; Impact=3; Risk Rating=5 Telnet TCP 23 • Used for remote access • Transmits data in cleartext • Often displays host system info • Even if it doesn't, the prompt may reveal system • May be used for attacking accounts if lockout not used • May reveal valid usernames from login attempts Countermeasures • Turn off • Use secure shell (SSH) instead • Modify banner messages • Modify error messages • Account locking/drop connection on login failure

  12. SMTP Enumeration Popularity=5; Simplicity=9; Impact=1; Risk Rating=5 Simple Mail Transport Protocol – TCP 25 • Used universally for email transfer • ASCII protocol for requests/replies • VRFY – verify user names • EXPN – provide actual delivery email address of alias • vrfy.pl script allows a file containing a list of user names to be tested and valid user names reported Countermeasures • Configure to turn off VRFY and EXPN, or • Configure to require authentication/privileges to use them

  13. DNS Enumeration - 1 Popularity=5; Simplicity=9; Impact=2; Risk Rating=5 Domain Name Service (DNS) – TCP/UDP 53 • Used for footprinting already • UDP used for most interactions • TCP for zone transfers • Zone transfer dumps entire contents of zone files • HINFO, hostname-IP mappings • SRV records allow search by service type • Nslookup, dig to access • BIND (Berkeley Internet Name Domain) enumeration • Reveals BIND version • Often allows zone transfer

  14. DNS Enumeration - 2 Domain Name Service (DNS) • DNS Cache snooping • DNS servers cache responses to recent queries • Attacker can force server to only use cache • +norecurse option in dig • Find recent accesses (or not) to particular FQDN • Answer flag set to 0 if not, 1 if recent access • Automated DNS Enumeration • Dnsenum (code.google.com/p/dnsenum/) • Fierce.pl (ha.ckers.org/fierce) • Web services for same (e.g., centralops.net) Countermeasures • Two DNS servers – one for public, one for private use • Block DNS zone transfers except to authorized hosts • Block version.bind requests • Disable DNS cache-snooping

  15. TFTP Enumeration Popularity=1; Simplicity=3; Impact=7; Risk Rating=3 Trivial FTP (TFTP) – TCP/UDP 69 • Quick-and-dirty FTP • Cleartext, no authentication • Requires knowledge of file name (exactly) • May allow download of sensitive file (e.g., /etc/passwd, /etc/shadow, network device configuration files, etc.) Countermeasures • Turn off, if possible • Wrap in TCP wrapper to restrict access • Limit access to /tftpboot/ directory • Block at border firewall

  16. Finger Enumeration Popularity=7; Simplicity=10; Impact=1; Risk Rating=6 Finger – TCP/UDP 79 • Reveals logged-in users, idle times • User info given from public file info Countermeasures • Turn off • Block port 79 • Restrict access • Restrict info given

  17. HTTP Enumeration Popularity=5; Simplicity=9; Impact=1; Risk Rating=5 Hypertext Transfer Protocol (HTTP) – TCP 80 • Get type and version of web server • HEAD can get banner info • But so popular with worms it can trigger IDS • If server uses SSL, use openssl or sll proxy to connect • Can download all web pages for offline search • Grendel-scan • Robots.txt file for “do not search” regions.... Countermeasures • Change banner • Microsoft IIS lockdown tool

  18. MSRPC Enumeration Popularity=7; Simplicity=8; Impact=1; Risk Rating=5 Microsoft Remote Procedure Call (MSRPC) – TCP 135 • RPC portmapper for windows • Gives list of services with version and IP/protocol/port info • Winfingerprint tool (sourceforge) • See hsc.fr/ressources/articles/win_net_srv Countermeasures • Restrict outside access • Require use of VPN for external access • Use OWA (Outlook Web Access) for remote mail access

  19. NBNS Enumeration Popularity=7; Simplicity=5; Impact=3; Risk Rating=5 NetBIOS Name Service (NBNS) – UDP 137 • Early windows version of DNS • net view command • Usually only works on local LAN segment • /domain for domains • /domain:dname for hosts on specific domain (dname) • nltest tool – identifies domain controllers (with auth creds) • netviewx tool – lists servers with specific services • nbstat, nbtscan – dump netbios name table, with users • nmbscan tool for Linux Countermeasures • Restrict access on hosts, routers (test – may break apps) • Disable Alerter and Messenger Service on hosts

  20. SMB Null Session Enumeration Popularity=8; Simplicity=10; Impact=8; Risk Rating=9 Server Message Block (SMB) Null Session – TCP 139/445 • Windows NT and descendents – file and print sharing • Samba in Linux • Can give remote access to attacker • a.k.a. Red Button, anonymous login, null session connection

  21. SMB Null Session (2) Establish “null session” • C:\>net use \\192.168.202.33\IPC$ “” /u:“” • Similar to mount network drive command • Connects to hidden IPC share at given IP as built-in anonymous user (/u:“”) with null password (“”) • Allows access to targeted host Enumerating File Shares • C:\>net view \\host • Shows IP address and shares on remote systems • Srvcheck, srvinfo (microsoft.com/downloads/...) • DumpSec (nee DumpAcl) – SomarSoft.com • Wholesale approach – for sysadmin (not hacker) • ShareEnum (SysInternal) • Networkscanner (SoftPerfect)

  22. SMB Null Session (3) Share Scanning wholesale for hackers • Includes password brute-forcing (may be intelligent) • Legion • NetBIOS Auditing Tool (NAT) (see hackingexposed.com) Registry Enumeration • Registry holds keys indicating applications installed • Also holds user info • and services • and holds configuration info (e.g., lockout number for failed password attempts) • Also may hold pointers to back doors • All of which can suggest exploits • Check if Registry is locked down using reg

  23. SMB Null Session (4) Enumerating Trusted Domains • Nltest /server:server_name /trusted_domains User Enumeration • DumpSec • List of users, groups, system policies, user rights • Following work with RestrictAnonymous=1, with null session • UserInfo/UserDump (hammerofgod.com) • GetAcct (securityFriday.com) • sid2user & user2sid (evgenii.rudnyi.ru/soft/sid/sid.txt) • SID is security ID – variable length value set at install • See alsohttp://en.wikipedia.org/wiki/Security_Identifier • User IDs (and much more) based on SID

  24. SMB Null Session (5) SIDs • C:\>user2sid \\targetIP “domain users” • Returns SID of host (hyphenated, S-1-...) • Digits following last hyphen is Relative ID (RID) • RID predefined for built-in users and groups • 500=admin • 501=guest • RID for users starts at 1000 for NT and increments • RID not reused => can see users past and present All-in-one tools • Cain & Abel (oxid.it/cain.html) • Winfingerprint (sourceforge.net) – also Active Directory, WMI • NBTEnum (try on packetstorm) – includes intelligent BF attack • enum (BindView, Symantec). Enum4linux (Portcullis Security) • NetE (cult of the dead cow) • Winfo (ntsecurity.nu)

  25. SMB Null Session (6) Popularity=8; Simplicity=10; Impact=8; Risk Rating=9 Countermeasures • Filter TCP/UDP ports 139 & 445 at perimeter • Self audit • Unbind WINS Client, or • Set RestrictAnonymous key (=0 is open, =1 can be bypassed, =2 means no null sessions possible) in NT • More granular access control in later Windows versions • HKLM\System\CurrentControlSet\Control\SecurePipeServer\Winreg and subkeys (e.g., AllowedPaths)

  26. SNMP Enumeration Popularity=7; Simplicity=9; Impact=3; Risk Rating=6 Simple Network Management Protocol – UDP 161 • “Security Not My Problem” - lacks strong protections • Password authentication – well-known default pw • Access to get and set MIBs (mgt info bases) • Vendor specific extensions to MIBs • Uses ASN.1 syntax for object IDs (OIDs)

  27. SNMP Enumeration (2) Tools • Snmputil, snmpget, snmpwalk commandline tools • Snmpget (linux/unix) in net-snmp suite at SourceForge • Copy-router-config.pl (muts) • IP Network Browser – GUI tool (solarwinds.com) Targets • Running services • Share names • Share paths • Comments on shares • Usernames • Domain name • Architecture, OS version

  28. SNMP Enumeration (3) SNMP Scanners • Simple, light-weight => perfect for automated scanning • SNScan (mcafee.com/us/downloads/free-tools/snscan.aspx) • Community and range to scan (or in file) • Hostname and (MIB version of) OS version • Csv file export • onesixtyone (portcullis-security.com/16.php) • Command line version of SNScan Countermeasures • Remove or disable SNMP agents on hosts • Use obscure community names (e.g., NOT “public” or “private”) • Block port 161 at all perimeter network access devices • Restrict access to specific IP addresses • Use SNMPv3 (more secure) • Set Registry to permit only authorized access

  29. BGP Enumeration Popularity=2; Simplicity=6; Impact=2; Risk Rating=3 Border Gateway Protocol (BGP) – TCP 179 • Interdomain routing protocol • Determine Autonomous Systems Number (ASN) of target • Query routers to get all networks where AS Path ends with desired ASN • Only uses IP addresses and ASNs • Get ASN from whois search (if name known) • Get ASN from router using IP address (if known) • Use telnet to router – show ASN path • Use last ASN on list as target ASN • May be false if BGP not used!!! Countermeasures - none

  30. Active Directory LDAP Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 Active Directory LDAP Countermeasures

  31. Unix RPC Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 Unix Remote Procedure Call (RPC) Countermeasures

  32. rwho, rusers Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 rwho, rusers Countermeasures

  33. NIS Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 NIS Countermeasures

  34. SQL Resolution Service Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 SQL Resolution Service Countermeasures

  35. Oracle TNS Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 Oracle TNS Countermeasures

  36. NFS Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 NFS Countermeasures

  37. IPSec/IKE Enumeration Popularity=1; Simplicity=10; Impact=1; Risk Rating=4 IPSec/IKE Countermeasures

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