Cutting Edge VoIP Security Issues Color

1
Hacking Exposed VoIP
Mark D. CollierChief Technology
OfficerSecureLogix Corporationmark.collier_at_secur
elogix.com
2
Outline
Outline

• Overview
• Gathering Information
• Footprinting
• Scanning
• Enumeration
• Attacking the Network
• Network Infrastructure Denial of Service
• Network Eavesdropping
• Network and Application Interception

3
Outline
Outline

• Attacking the Application
• Fuzzing
• Disruption of Service
• Signaling and Media Manipulation
• Social Attacks
• Voice SPAM/SPIT
• Voice Phishing

4
Introduction
Introduction

• VoIP systems are vulnerable
• Platforms, networks, and applications are
  vulnerable
• VoIP-specific attacks are becoming more common
• Security isnt always a consideration during
  deployment
• The threat is increasing
• VoIP deployment is growing
• Deployments are critical to business operations
• Greater integration with the data network
• More attack tools being published
• The hacking community is taking notice

5
Gathering Information
Gathering Information

• This is the process a hacker goes through to
  gather information about your organization and
  prepare their attack
• Consists of
• Footprinting
• Scanning
• Enumeration

6
Footprinting
Gathering InformationFootprinting

• Steps taken by a hacker to learn about your
  enterprise before they start the actual attack
• Consists of
• Public website research
• Google hacking

7
Public Website ResearchIntroduction
Gathering InformationFootprinting

• An enterprise website often contains a lot of
  information that is useful to a hacker
• Organizational structure and corporate locations
• Help and technical support
• Job listings
• Phone numbers and extensions

8
Public Website ResearchJob Listings
Gathering InformationFootprinting

• Job listings can contain a ton of information
  about the enterprise VoIP system.
• Here is a portion of an actual job listing
• Required Technical SkillsMinimum 3-5 years
  experience in the management and implementation
  of Avaya telephone systems/voicemails
• Advanced programming knowledge of the Avaya
  Communication Servers and voicemails.

9
Public Website ResearchPhone Numbers
Gathering InformationFootprinting

• Google can be used to find all phone numbers on
  an enterprise web site
• Type 111..999-1000..9999 sitewww.mcgraw-hill.co
  m

10
Public Website ResearchVoice Mail
Gathering InformationFootprinting

• By calling into some of these numbers, you can
  listen to the voice mail system and determine the
  vendor
• Check out our voice mail hacking database at
• www.hackingvoip.com

11
Public Website Research Countermeasures
Gathering InformationFootprinting

• It is difficult to control what is on your
  enterprise website, but it is a good idea to be
  aware of what is on it
• Try to limit amount of detail in job postings
• Remove technical detail from help desk web pages

12
Google HackingIntroduction
Gathering InformationFootprinting

• Google is incredibly good at finding details on
  the web
• Vendor press releases and case studies
• Resumes of VoIP personnel
• Mailing lists and user group postings
• Web-based VoIP logins

13
Google Hacking
Gathering InformationFootprinting

• Vendors and enterprises may post press releases
  and case studies
• Type siteavaya.com case study or
  siteavaya.com company
• Users place resumes on the Internet when
  searching for jobs
• Search Monster for resumes for company employees
• Mailing lists and user group postings
• www.inuaa.org
• www.innua.org
• forums.cisco.com
• forums.digium.com

14
Google HackingWeb-Based VoIP Logins
Gathering InformationFootprinting

• Use Google to search for
• Type inrulccmuser/logon.asp
• Type inurlccmuser/logon.asp siteexample.com
• Type inurlNetworkConfiguration cisco

15
Google HackingCountermeasures
Gathering InformationFootprinting

• Determine what your exposure is
• Be sure to remove any VoIP phones which are
  visible to the Internet
• Disable the web servers on your IP phones
• There are services that can helpyou monitor your
  exposure
• www.cyveilance.com
• ww.baytsp.com

16
ScanningIntroduction
Gathering InformationScanning

• Steps taken by a hacker to identify IP addresses
  and hosts running VoIP
• Consists
• Gaining access
• Host/device discovery and identification
• Port scanning and service discovery

17
ScanningGaining Access
Attacking The NetworkGaining Access

• Several attack vectors include
• Installing a simple wired hub
• Wi-Fi sniffing
• Compromising a network node
• Compromising a VoIP phone
• Compromising a switch
• Compromising a proxy, gateway, or PC/softphone
• ARP poisoning
• Circumventing VLANs

18
Host/DeviceDiscovery and Identification
Gathering InformationScanning

• Consists of various techniques used to find
  hosts
• Ping sweeps
• ARP pings
• TCP ping scans
• SNMP sweeps
• After hosts are found, the type of device can be
  determined
• Classifies host/device by operating system
• Network stack fingerprinting is a common
  technique for identifying hosts/devices

19
Host/Device DiscoveryUsing nmap
Gathering InformationScanning

• nmap -O -P0 192.168.1.1-254
• Starting Nmap 4.01 ( http//www.insecure.org/nmap/
  ) at 2006-02-20 0103 CST
• Interesting ports on 192.168.1.21
• (The 1671 ports scanned but not shown below are
  in state filtered)
• PORT STATE SERVICE
• 23/tcp open telnet
• MAC Address 000F34118045 (Cisco Systems)
• Device type VoIP phone
• Running Cisco embedded
• OS details Cisco IP phone (POS3-04-3-00,
  PC030301)
• Interesting ports on 192.168.1.23
• (The 1671 ports scanned but not shown below are
  in state closed)
• PORT STATE SERVICE
• 80/tcp open http
• MAC Address 00156286BA3E (Cisco Systems)
• Device type VoIP phoneVoIP adapter
• Running Cisco embedded
• OS details Cisco VoIP Phone [phone] or ATA 186
  Analog Telephone Adapter

20
Host/Device DiscoveryPing Sweeps/ARP Pings
Gathering InformationScanning
21
Host/Device DiscoverySNMP Sweeps
Gathering InformationScanning
22
Host/Device DiscoveryCountermeasures
Gathering InformationScanning

• Use firewalls and Intrusion Prevention Systems
  (IPSs) to block ping and TCP sweeps
• VLANs can help isolate ARP pings
• Ping sweeps can be blocked at the perimeter
  firewall

23
Port Scanning/Service Discovery
Gathering InformationScanning

• Consists of various techniques used to find open
  ports and services on hosts
• These ports can be targeted later
• nmap is the most commonly used tool for TCP SYN
  and UDP scans

24
Port Scanning/Service DiscoveryCountermeasures
Gathering InformationScanning

• Using non-Internet routable IP addresses will
  prevent external scans
• Firewalls and IPSs can detect and possibly block
  scans
• VLANs can be used to partition the network to
  prevent scans from being effective

25
EnumerationIntroduction
Gathering InformationEnumeration

• Involves testing open ports and services on
  hosts/devices to gather more information
• Includes running tools to determine if open
  services have known vulnerabilities
• Also involves scanning for VoIP-unique
  information such as phone numbers
• Includes gathering information from TFTP servers
  and SNMP

26
Vulnerability TestingTools
Gathering InformationEnumeration
27
Vulnerability TestingTools
Gathering InformationEnumeration
28
Vulnerability TestingTools
Gathering InformationEnumeration
29
Vulnerability TestingCountermeasures
Gathering InformationEnumeration

• The best solution is to upgrade your applications
  and make sure you continually apply patches
• Some firewalls and IPSs can detect and mitigate
  vulnerability scans

30
SIP EnumerationDirectory Scanning
Gathering InformationEnumeration

• root_at_attacker nc 192.168.1.104 5060
• OPTIONS siptest_at_192.168.1.104 SIP/2.0
• Via SIP/2.0/TCP 192.168.1.120branch4ivBcVj5ZnPY
  gb
• To alice ltsiptest_at_192.168.1.104gt
• Content-Length 0
• SIP/2.0 404 Not Found
• Via SIP/2.0/TCP
• 192.168.1.120branch4ivBcVj5ZnPYgbreceived192.1
  68.1.103
• To alice siptest_at_192.168.1.104gttagb27e1a1d3376
  1e85846fc98f5f3a7e58.0503
• Server Sip EXpress router (0.9.6 (i386/linux))
• Content-Length 0
• Warning 392 192.168.1.1045060 "Noisy feedback
  tells pid29801
• req_src_ip192.168.1.120 req_src_port32773
  in_urisiptest_at_192.168.1.104
• out_urisiptest_at_192.168.1.104 via_cnt1"

31
SIP EnumerationDirectory Scanning
Gathering InformationEnumeration
32
TFTP EnumerationIntroduction
Gathering InformationEnumeration

• Almost all phones we tested use TFTP to download
  their configuration files
• The TFTP server is rarely well protected
• If you know or can guess the name of a
  configuration or firmware file, you can download
  it without even specifying a password
• The files are downloaded in the clear and can be
  easily sniffed
• Configuration files have usernames, passwords, IP
  addresses, etc. in them

33
TFTP EnumerationUsing TFTPBRUTE
Gathering InformationEnumeration

• root_at_attacker perl tftpbrute.pl 192.168.1.103
  brutefile.txt 100tftpbrute.pl, , V 0.1
• TFTP file word database brutefile.txt
• TFTP server 192.168.1.103
• Max processes 100
• Processes are 1
• ltsnipgt
• Processes are 12
• Found TFTP server remote filename sip.cfg
• Found TFTP server remote filename
  46xxsettings.txt
• Processes are 13
• Processes are 14
• Found TFTP server remote filename
  sip_4602D02A.txt
• Found TFTP server remote filename
  XMLDefault.cnf.xml
• Found TFTP server remote filename
  SipDefault.cnf

34
TFTP EnumerationCountermeasures
Gathering InformationEnumeration

• It is difficult not to use TFTP, since it is so
  commonly used by VoIP vendors
• Some vendors offer more secure alternatives
• Firewalls can be used to restrict access to TFTP
  servers to valid devices

35
SNMP EnumerationIntroduction
Gathering InformationEnumeration

• SNMP is enabled by default on most IP PBXs and IP
  phones
• Simple SNMP sweeps will garner lots of useful
  information
• If you know the device type, you can use snmpwalk
  with the appropriate OID
• You can find the OID using Solarwinds MIB
• Default passwords, called community strings,
  are common

36
SNMP EnumerationSolarwinds
Gathering InformationEnumeration
37
SNMP Enumerationsnmpwalk
Gathering InformationEnumeration

• root_at_domain2 snmpwalk -c public -v 1
  192.168.1.53 1.3.6.1.4.1.6889
• SNMPv2-SMIenterprises.6889.2.69.1.1.1.0
  STRING "Obsolete"
• SNMPv2-SMIenterprises.6889.2.69.1.1.2.0
  STRING "4620D01B"
• SNMPv2-SMIenterprises.6889.2.69.1.1.3.0
  STRING "AvayaCallserver"
• SNMPv2-SMIenterprises.6889.2.69.1.1.4.0
  IpAddress 192.168.1.103
• SNMPv2-SMIenterprises.6889.2.69.1.1.5.0
  INTEGER 1719
• SNMPv2-SMIenterprises.6889.2.69.1.1.6.0
  STRING "051612501065"
• SNMPv2-SMIenterprises.6889.2.69.1.1.7.0
  STRING "700316698"
• SNMPv2-SMIenterprises.6889.2.69.1.1.8.0
  STRING "051611403489"
• SNMPv2-SMIenterprises.6889.2.69.1.1.9.0
  STRING "00040D5040B0"
• SNMPv2-SMIenterprises.6889.2.69.1.1.10.0
  STRING "100"
• SNMPv2-SMIenterprises.6889.2.69.1.1.11.0
  IpAddress 192.168.1.53
• SNMPv2-SMIenterprises.6889.2.69.1.1.12.0
  INTEGER 0
• SNMPv2-SMIenterprises.6889.2.69.1.1.13.0
  INTEGER 0
• SNMPv2-SMIenterprises.6889.2.69.1.1.14.0
  INTEGER 0
• SNMPv2-SMIenterprises.6889.2.69.1.1.15.0
  STRING "192.168.1.1"
• SNMPv2-SMIenterprises.6889.2.69.1.1.16.0
  IpAddress 192.168.1.1
• SNMPv2-SMIenterprises.6889.2.69.1.1.17.0
  IpAddress 255.255.255.0

38
SNMP EnumerationCountermeasures
Gathering InformationEnumeration

• Disable SNMP on any devices where it is not
  needed
• Change default public and private community
  strings
• Try to use SNMPv3, which supports authentication

39
Attacking The Network
Attacking The Network

• The VoIP network and supporting infrastructure
  are vulnerable to attacks
• Most attacks will originate inside the network,
  once access is gained
• Attacks include
• Network infrastructure DoS
• Network eavesdropping
• Network and application interception

40
Attacking The NetworkGaining Access
Attacking The NetworkGaining Access

• Some techniques for circumventing VLANs
• Without MAC filtering, disconnect a phone and
  connect a PC
• Even if MAC filtering is used, you can easily
  spoof the MAC
• Be especially cautious of VoIP phones in public
  areas
• Some other VLAN attacks
• MAC flooding attack
• 802.1q and ISL tagging attack
• Double-encapsulated 802.1q/Nested VLAN attack
• Private VLAN attack
• Spanning-tree protocol attack/VLAN trunking
  protocol attack

41
Network Infrastructure DoS
Attacking The NetworkNetwork DoS

• The VoIP network and supporting infrastructure
  are vulnerable to attacks
• VoIP media/audio is particularly susceptible to
  any DoS attack which introduces latency and
  jitter
• Attacks include
• Flooding attacks
• Network availability attacks
• Supporting infrastructure attacks

42
Flooding AttacksIntroduction
Attacking The NetworkNetwork DoS

• Flooding attacks generate so many packets at a
  target, that it is overwhelmed and cant process
  legitimate requests

43
Flooding AttacksTypes of Floods
Attacking The NetworkNetwork DoS

• Some types of floods are
• UDP floods
• TCP SYN floods
• ICMP and Smurf floods
• Worm and virus oversubscription side effect
• QoS manipulation
• Application flooding

44
Flooding AttacksCountermeasures
Attacking The NetworkNetwork DoS

• Layer 2 and 3 QoS mechanisms are commonly used to
  give priority to VoIP media (and signaling)
• Use rate limiting in network switches
• Use anti-DoS/DDoS products
• Some vendors have DoS support in their products
  (in newer versions of software)

45
Network Availability Attacks
Attacking The NetworkNetwork DoS

• This type of attack involves an attacker trying
  to crash the underlying operating system
• Fuzzing involves sending malformed packets, which
  exploit a weakness in software
• Packet fragmentation
• Buffer overflows

46
Network Availability Attacks Countermeasures
Attacking The NetworkNetwork DoS

• A network IPS is an inline device that detects
  and blocks attacks
• Some firewalls also offer this capability
• Host based IPS software also provides this
  capability

47
Supporting Infrastructure Attacks
Attacking The NetworkNetwork DoS

• VoIP systems rely heavily on supporting services
  such as DHCP, DNS, TFTP, etc.
• DHCP exhaustion is an example, where a hacker
  uses up all the IP addresses, denying service to
  VoIP phones
• DNS cache poisoning involves tricking a DNS
  server into using a fake DNS response

48
Supporting Infrastructure AttacksCountermeasures
Attacking The NetworkNetwork DoS

• Configure DHCP servers not to lease addresses to
  unknown MAC addresses
• DNS servers should be configured to analyze info
  from non-authoritative servers and dropping any
  response not related to queries

49
Network EavesdroppingIntroduction
Attacking The NetworkEavesdropping

• VoIP configuration files, signaling, and media
  are vulnerable to eavesdropping
• Attacks include
• TFTP configuration file sniffing (already
  discussed)
• Number harvesting and call pattern tracking
• Conversation eavesdropping

50
Numbers/Call Patterns
Attacking The NetworkEavesdropping

• By sniffing signaling, it is possible to build a
  directory of numbers and track calling patterns
• voipong automates the process of logging all
  calls
• Wireshark is very good at sniffing VoIP signaling

51
Conversation RecordingWireshark
Attacking The NetworkEavesdropping
52
Conversation RecordingWireshark
Attacking The NetworkEavesdropping
53
Conversation RecordingCain And Abel
Attacking The NetworkEavesdropping
54
Conversation RecordingOther Tools
Attacking The NetworkEavesdropping

• Other tools include
• vomit
• Voipong
• voipcrack (not public)
• DTMF decoder

55
Network EavesdroppingCountermeasures
Attacking The NetworkEavesdropping

• Use encryption
• Many vendors offer encryption for signaling
• Use the Transport Layer Security (TLS) for
  signaling
• Many vendors offer encryption for media
• Use Secure Real-time Transport Protocol (SRTP)
• Use ZRTP
• Use proprietary encryption if you have to

56
Network/Application InterceptionIntroduction
Attacking The NetworkNet/App Interception

• The VoIP network is vulnerable to
  Man-In-The-Middle (MITM) attacks, allowing
• Eavesdropping on the conversation
• Causing a DoS condition
• Altering the conversation by omitting, replaying,
  or inserting media
• Redirecting calls
• Attacks include
• Network-level interception
• Application-level interception

57
Network InterceptionARP Poisoning
Attacking The NetworkNet/App Interception

• The most common network-level MITM attack is ARP
  poisoning
• Involves tricking a host into thinking the MAC
  address of the attacker is the intended address
• There are a number of tools available to support
  ARP poisoning
• Cain and Abel
• ettercap
• Dsniff
• hunt

58
Network InterceptionARP Poisoning
Attacking The NetworkNet/App Interception
59
Network InterceptionARP Poisoning
Attacking The NetworkNet/App Interception
60
Network InterceptionCountermeasures
Attacking The NetworkNet/App Interception

• Some countermeasures for ARP poisoning are
• Static OS mappings
• Switch port security
• Proper use of VLANs
• Signaling encryption/authentication
• ARP poisoning detection tools, such as arpwatch

61
Attacking The Application
Attacking The Application

• VoIP systems are vulnerable to application
  attacks against the various VoIP protocols
• Attacks include
• Fuzzing attacks
• Flood-based DoS
• Signaling and media manipulation

62
FuzzingIntroduction
Attacking The ApplicationFuzzing

• Fuzzing describes attacks where malformed packets
  are sent to a VoIP system in an attempt to crash
  it
• Research has shown that VoIP systems, especially
  those employing SIP, are vulnerable to fuzzing
  attacks

63
FuzzingExample
Attacking The ApplicationFuzzing
INVITE sip6713_at_192.168.26.1806060userphone
SIP/2.0 Via SIP/2.0/UDP 192.168.22.366060 From
UserAgentltsip6710_at_192.168.22.366060userphonegt
To 6713ltsip6713_at_192.168.26.1806060userphonegt
Call-ID 96561418925909_at_192.168.22.36 Cseq 1
INVITE Subject VovidaINVITE Contact
ltsip6710_at_192.168.22.366060userphonegt Content-T
ype application/sdp Content-Length 168
64
FuzzingExample
Attacking The ApplicationFuzzing
INVITE sip6713_at_192.168.26.1806060userphone
SIP/2.0 Via aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaa aaaaaaaaaaaaa From
UserAgentltsip6710_at_192.168.22.366060userphonegt
To 6713ltsip6713_at_192.168.26.1806060userphonegt
Call-ID 96561418925909_at_192.168.22.36 Cseq 1
INVITE Subject VovidaINVITE Contact
ltsip6710_at_192.168.22.366060userphonegt Content-T
ype application/sdp Content-Length 168
65
FuzzingPublic Domain Tools
Attacking The ApplicationFuzzing

• There are many public domain tools available for
  fuzzing
• Protos suite
• Asteroid
• Fuzzy Packet
• NastySIP
• Scapy

• SipBomber
• SFTF
• SIP Proxy
• SIPp
• SIPsak

66
FuzzingCommercial Tools
Attacking The ApplicationFuzzing

• There are some commercial tools available
• Beyond Security BeStorm
• Codenomicon
• MuSecurity Mu-4000 Security Analyzer
• Security Innovation Hydra
• Sipera Systems LAVA tools

67
FuzzingCountermeasures
Attacking The ApplicationFuzzing

• Make sure your vendor has tested their systems
  for fuzzing attacks
• Consider running your own tests
• An VoIP-aware IPS can monitor for and block
  fuzzing attacks

68
Flood-Based DoS
Attacking The ApplicationFlood-Based DoS

• Several tools are available to generate floods at
  the application layer
• rtpflood generates a flood of RTP packets
• inviteflood generates a flood of SIP INVITE
  packets
• SiVuS a tool which a GUI that enables a variety
  of flood-based attacks
• Virtually every device we tested was susceptible
  to these attacks

69
Flood-Based DoSCountermeasures
Attacking The ApplicationFlood-Based DoS

• There are several countermeasures you can use for
  flood-based DoS
• Use VLANs to separate networks
• Use TCP and TLS for SIP connections
• Use rate limiting in switches
• Enable authentication for requests
• Use SIP firewalls/IPSs to monitor and block
  attacks

70
Signaling/Media ManipulationIntroduction
Attacking The Application Sig/Media Manipulation

• In SIP and RTP, there are a number of attacks
  possible, which exploit the protocol
• Registration manipulation
• Redirection attacks
• Session teardown
• SIP phone reboot
• RTP insertion/mixing

71
Registration Manipulation
Attacking The Application Sig/Media Manipulation
72
Redirection Attacks
Attacking The Application Sig/Media Manipulation
73
Session Teardown
Attacking The Application Sig/Media Manipulation

74
IP Phone Reboot
Attacking The Application Sig/Media Manipulation

75
Audio Insertion/Mixing
Attacking The Application Sig/Media Manipulation

Attacker SeesPackets AndInserts/Mixes InNew
Audio
76
Signaling/Media ManipulationCountermeasures
Attacking The Application Sig/Media Manipulation

• Some countermeasures for signaling and media
  manipulation include
• Use digest authentication where possible
• Use TCP and TLS where possible
• Use SIP-aware firewalls/IPSs to monitor for and
  block attacks
• Use audio encryption to prevent RTP
  injection/mixing

77
Social Attacks
Social Attacks

• There are a couple of evolving social threats
  that will affect enterprises
• Voice SPAM or SPAM over Internet Telephony (SPIT)
• Voice phishing

78
Voice SPAMIntroduction
Social AttacksVoice SPAM

• Voice SPAM refers to bulk, automatically
  generated, unsolicited phone calls
• Similar to telemarketing, but occurring at the
  frequency of email SPAM
• Not an issue yet, but will become prevalent when
• The network makes it very inexpensive or free to
  generate calls
• Attackers have access to VoIP networks that allow
  generation of a large number of calls
• It is easy to set up a voice SPAM operation,
  using Asterisk, tools like spitter, and free
  VoIP access

79
Voice SPAM
Social AttacksVoice SPAM

• Voice SPAM has the potential to be very
  disruptive because
• Voice calls tend to interrupt a user more than
  email
• Calls arrive in realtime and the content cant be
  analyzed to determine it is voice SPAM
• Even calls saved to voice mail must be converted
  from audio to text, which is an imperfect process
• There isnt any capability in the protocols that
  looks like it will address Voice SPAM

80
Voice SPAMCountermeasures
Social AttacksVoice SPAM

• Some potential countermeasures for voice SPAM
  are
• Authenticated identity movements, which may help
  to identify callers
• Legal measures
• Enterprise voice SPAM filters
• Black lists/white lists
• Approval systems
• Audio content filtering
• Turing tests

81
VoIP PhishingIntroduction
Social AttacksPhishing

• Similar to email phishing, but with a phone
  number delivered though email or voice
• When the victim dials the number, the recording
  requests entry of personal information
• The hacker comes back later and retrieves the
  touch tones or other information

82
VoIP PhishingExample
Social AttacksPhishing

• Hi, this is Bob from Bank of America calling.
  Sorry I missed you. If you could give us a call
  back at 1-866-555-1324 we have an urgent issue to
  discuss with you about your bank account.
• Hello. This is Bank of America. So we may best
  serve you, please enter your account number
  followed by your PIN.

83
VoIP PhishingExample
Social AttacksPhishing
84
VoIP PhishingCountermeasures
Social AttacksPhishing

• Traditional email spam/phishing countermeasures
  come in to play here.
• Educating users is a key

85
Final Thoughts
Social AttacksPhishing

• VoIP systems can be secured, but are often
  installed in a non-secure way
• A VoIP security assessment/audit is a great way
  to identify issues and countermeasures
• Dont forget about legacy systems. Issues still
  exist and VoIP can make some worse