Post on 23-Mar-2016
description
Voice Over IP Security
Mark D. CollierChief Technology OfficerSecureLogix Corporationmark.collier@securelogix.com
David EndlerDirector of Security Research
TippingPointdendler@tippingpoint.com
Overview
Gathering Information: Footprinting Scanning Enumeration
Attacking the Network: Network Infrastructure Denial of Service Network Eavesdropping Network and Application Interception
OutlineOutline
Attacking Vendor Platforms: Avaya Cisco
Attacking the Application: Fuzzing Disruption of Service Signaling and Media Manipulation
Social Attacks: Voice SPAM/SPIT Voice Phishing
OutlineOutline
VoIP systems are vulnerable: Platforms, networks, and applications are vulnerable VoIP-specific attacks are becoming more common Security isn’t 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
IntroductionIntroductionIntroduction
This is the process a hacker goes through to gather information about your organization and prepare their attack
Consists of: Footprinting Scanning Enumeration
Gathering InformationGathering Information
Steps taken by a hacker to learn about your enterprise before they start the actual attack
Consists of: Public website research Google hacking
FootprintingGathering 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
Public Website ResearchIntroduction
Gathering InformationFootprinting
Public Website ResearchCorporate Locations
Gathering InformationFootprinting
Public Website ResearchJob Listings
Job listings can contain a ton of information about the enterprise VoIP system.
Here is a portion of an actual job listing:Required Technical Skills:
Minimum 3-5 years experience in the management and implementation of Avaya telephone systems/voicemails:
* Advanced programming knowledge of the Avaya Communication Servers and voicemails.
Gathering InformationFootprinting
Public Website ResearchPhone Numbers
Google can be used to find all phone numbers on an enterprise web site: Type: “111..999-1000..9999 site:www.mcgraw-hill.com”
Gathering InformationFootprinting
Public Website ResearchVoice Mail
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
Gathering InformationFootprinting
Public Website Research Countermeasures
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
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
Google HackingIntroduction
Gathering InformationFootprinting
Vendors and enterprises may post press releases and case studies: Type: “site:avaya.com case study” or “site:avaya.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
Google Hacking Gathering InformationFootprinting
Use Google to search for: Type: inrul:”ccmuser/logon.asp” Type: inurl:”ccmuser/logon.asp” site:example.com Type: inurl:”NetworkConfiguration” cisco
Google HackingWeb-Based VoIP Logins
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
Google HackingCountermeasures
Gathering InformationFootprinting
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
ScanningIntroduction
Gathering InformationScanning
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
ScanningGaining Access
Attacking The NetworkGaining Access
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
Host/DeviceDiscovery and Identification
Gathering InformationScanning
Host/Device DiscoveryUsing nmap
nmap -O -P0 192.168.1.1-254
Starting Nmap 4.01 ( http://www.insecure.org/nmap/ ) at 2006-02-20 01:03 CSTInteresting ports on 192.168.1.21:(The 1671 ports scanned but not shown below are in state: filtered)PORT STATE SERVICE23/tcp open telnetMAC Address: 00:0F:34:11:80:45 (Cisco Systems)Device type: VoIP phoneRunning: Cisco embeddedOS 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 SERVICE80/tcp open httpMAC Address: 00:15:62:86:BA:3E (Cisco Systems)Device type: VoIP phone|VoIP adapterRunning: Cisco embeddedOS details: Cisco VoIP Phone 7905/7912 or ATA 186 Analog Telephone AdapterInteresting ports on 192.168.1.24:(The 1671 ports scanned but not shown below are in state: closed)PORT STATE SERVICE80/tcp open httpMAC Address: 00:0E:08:DA:DA:17 (Sipura Technology)Device type: VoIP adapterRunning: Sipura embeddedOS details: Sipura SPA-841/1000/2000/3000 POTS<->VoIP gateway
Gathering InformationScanning
Host/Device DiscoveryPing Sweeps/ARP Pings
Gathering InformationScanning
Host/Device DiscoverySNMP Sweeps
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
Use secure (SNMPv3) version of SNMP
Change SNMP public strings
Host/Device DiscoveryCountermeasures
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
Port Scanning/Service Discovery 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
Port Scanning/Service DiscoveryCountermeasures
Gathering InformationScanning
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
EnumerationIntroduction
Gathering InformationEnumeration
Vulnerability TestingTools
Gathering InformationEnumeration
Vulnerability TestingTools
Gathering InformationEnumeration
Vulnerability TestingTools
Gathering InformationEnumeration
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
SIP EnumerationDirectory Scanning[root@attacker]# nc 192.168.1.104 5060
OPTIONS sip:test@192.168.1.104 SIP/2.0Via: SIP/2.0/TCP 192.168.1.120;branch=4ivBcVj5ZnPYgbTo: alice <sip:test@192.168.1.104>Content-Length: 0
SIP/2.0 404 Not FoundVia: SIP/2.0/TCP192.168.1.120;branch=4ivBcVj5ZnPYgb;received=192.168.1.103To: alice sip:test@192.168.1.104>;tag=b27e1a1d33761e85846fc98f5f3a7e58.0503Server: Sip EXpress router (0.9.6 (i386/linux))Content-Length: 0Warning: 392 192.168.1.104:5060 "Noisy feedback tells: pid=29801req_src_ip=192.168.1.120 req_src_port=32773 in_uri=sip:test@192.168.1.104out_uri=sip:test@192.168.1.104 via_cnt==1"
Gathering InformationEnumeration
SIP EnumerationDirectory Scanning
Gathering InformationEnumeration
TFTP EnumerationIntroduction
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
Gathering InformationEnumeration
TFTP EnumerationUsing TFTPBRUTE[root@attacker]# perl tftpbrute.pl 192.168.1.103
brutefile.txt 100tftpbrute.pl, , V 0.1
TFTP file word database: brutefile.txtTFTP server 192.168.1.103Max processes 100 Processes are: 1<snip>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
Gathering InformationEnumeration
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
SNMP EnumerationIntroduction
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
Gathering InformationEnumeration
SNMP EnumerationSolarwinds
Gathering InformationEnumeration
SNMP Enumerationsnmpwalk
[root@domain2 ~]# snmpwalk -c public -v 1 192.168.1.53 1.3.6.1.4.1.6889
SNMPv2-SMI::enterprises.6889.2.69.1.1.1.0 = STRING: "Obsolete"SNMPv2-SMI::enterprises.6889.2.69.1.1.2.0 = STRING: "4620D01B"SNMPv2-SMI::enterprises.6889.2.69.1.1.3.0 = STRING: "AvayaCallserver"SNMPv2-SMI::enterprises.6889.2.69.1.1.4.0 = IpAddress: 192.168.1.103SNMPv2-SMI::enterprises.6889.2.69.1.1.5.0 = INTEGER: 1719SNMPv2-SMI::enterprises.6889.2.69.1.1.6.0 = STRING: "051612501065"SNMPv2-SMI::enterprises.6889.2.69.1.1.7.0 = STRING: "700316698"SNMPv2-SMI::enterprises.6889.2.69.1.1.8.0 = STRING: "051611403489"SNMPv2-SMI::enterprises.6889.2.69.1.1.9.0 = STRING: "00:04:0D:50:40:B0"SNMPv2-SMI::enterprises.6889.2.69.1.1.10.0 = STRING: "100"SNMPv2-SMI::enterprises.6889.2.69.1.1.11.0 = IpAddress: 192.168.1.53SNMPv2-SMI::enterprises.6889.2.69.1.1.12.0 = INTEGER: 0SNMPv2-SMI::enterprises.6889.2.69.1.1.13.0 = INTEGER: 0SNMPv2-SMI::enterprises.6889.2.69.1.1.14.0 = INTEGER: 0SNMPv2-SMI::enterprises.6889.2.69.1.1.15.0 = STRING: "192.168.1.1"SNMPv2-SMI::enterprises.6889.2.69.1.1.16.0 = IpAddress: 192.168.1.1SNMPv2-SMI::enterprises.6889.2.69.1.1.17.0 = IpAddress: 255.255.255.0...SNMPv2-SMI::enterprises.6889.2.69.1.4.8.0 = INTEGER: 20SNMPv2-SMI::enterprises.6889.2.69.1.4.9.0 = STRING: "503"
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
SNMP EnumerationCountermeasures
Gathering InformationEnumeration
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
Attacking The NetworkAttacking The Network
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
Attacking The NetworkGaining Access
Attacking The NetworkGaining Access
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
Network Infrastructure DoSAttacking The NetworkNetwork DoS
Flooding attacks generate so many packets at a target, that it is overwhelmed and can’t process legitimate requests
Flooding AttacksIntroduction
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
Flooding AttacksTypes of Floods
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)
Flooding AttacksCountermeasures
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
Network Availability AttacksAttacking 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
Network Availability Attacks Countermeasures
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
Supporting Infrastructure AttacksAttacking 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
Supporting Infrastructure AttacksCountermeasures
Attacking The NetworkNetwork DoS
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
Network EavesdroppingIntroduction
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
Numbers/Call Patterns Attacking The NetworkEavesdropping
Conversation RecordingWireshark
Attacking The NetworkEavesdropping
Attacking The NetworkEavesdroppingConversation Recording
Wireshark
Attacking The NetworkEavesdroppingConversation Recording
Cain And Abel
Other tools include: vomit Voipong voipcrack (not public) DTMF decoder
Conversation RecordingOther Tools
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
Network EavesdroppingCountermeasures
Attacking The NetworkEavesdropping
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
Network/Application InterceptionIntroduction
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
Network InterceptionARP Poisoning
Attacking The NetworkNet/App Interception
Network InterceptionARP Poisoning
Attacking The NetworkNet/App Interception
Network InterceptionARP Poisoning
Attacking The NetworkNet/App Interception
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
This section describes unique attacks against specific VoIP vendor platforms, including: Avaya Cisco
Attacking The PlatformAttacking The Platform
The Avaya Communication Manager is Avaya’s enterprise-class offering
Offers strong security, but some default configuration should be changed
Avaya uses Linux and VxWorks as the underlying operating system on many components, which is arguably more secure than Windows
Avaya Communication ManagerAttacking The PlatformAvaya
Avaya Communication ManagerAttacking The PlatformAvaya
Open Ports Attacking The PlatformAvaya
Open Ports Attacking The PlatformAvaya
Open Ports Attacking The PlatformAvaya
Open Ports Attacking The PlatformAvaya
Open Ports Attacking The PlatformAvaya
Open Ports Attacking The PlatformAvaya
Open PortsCountermeasures
Attacking The PlatformAvaya
Open PortsCountermeasures
Attacking The PlatformAvaya
SNMP and TFTP Attacking The PlatformAvaya
Avaya uses TFTP and SNMP
In 3.0, SNMP is enabled by default on the IP PBX and IP phones
Some components ship with default public and private community strings
SNMP and TFTPCountermeasures
Attacking The PlatformAvaya
Use the same countermeasures as before
Avaya provides a secure copy feature as an alternative to TFTP
Communication Manager 4.0 disables SNMP by default
Version 2.6 for IP phones does not ship with default community strings
Flooding Attacks Attacking The PlatformAvaya
We used udpflood and tcpsynflood to perform DoS attacks against various components
Unfortunately, these attacks were very disruptive
Flooding AttacksCountermeasures
Attacking The PlatformAvaya
Use the same countermeasures as before
Avaya C-LAN cards provide some level of DoS mitigation
Newer IP phone software provides better DoS mitigation
http://support.avaya.com/security
Miscellaneous Security Issues Attacking The PlatformAvaya
Avaya signaling and media are vulnerable to eavesdropping
Avaya uses some default passwords on key IP PBX components
Password recommendations for IP phones are weak
By default, Avaya IP phones can be reconfigured when booted
Miscellaneous Security IssuesCountermeasures
Attacking The PlatformAvaya
Avaya supports proprietary encryption for signaling and media. SRTP will be supported in Communication Manager 4.0
Default passwords should be changed to strong values
Local access to the IP phone can be controlled with a password
The Cisco Unified Call Manager is Cisco’s enterprise class offering
Offers strong security, but requires some configuration
Version 4.1 is based on Windows. Version 5.0 is based on Linux
A Must Read Document is the Solution Reference Network Design (SRND) for Voice communications. (http://tinyurl.com/gd5r4).
Includes great deployment scenarios and security use cases (lobby phone, desktop phone, call manager encryption how-to, etc.)
Cisco Unified Call ManagerAttacking The PlatformAvaya
CiscoIntroduction
Attacking The PlatformCisco
Cisco Discovery Protocol – Cisco’s proprietary layer 2 network management protocol.
Contains juicy information that is broadcast on the entire segment
Cisco Discovery ProtocolAttacking The PlatformCisco
Cisco Unified Call Manager requires a large number of open ports
Port ScanningAttacking The PlatformCisco
Cisco IOS has a great feature called “autosecure” that” disables a slew of services (finger, http, ICMP, source routing,
etc.) enables some services (password encryption, TCP synwait-time,
logging, etc.). And locks down the router and switch (enables only ssh, blocks
private address blocks from traversing, enables netflow, etc.)
Port ScanningCountermeasures
Attacking The PlatformCisco
Network Flooding Countermeasures: Another great feature from Cisco is AutoQos, a new IOS feature
(auto qos command). Enables Quality of Service for VoIP traffic across every Cisco
router and switch Scavenger class QoS also a relatively new Cisco strategy – rate
shape all bursty non-VoIP traffic
FloodingCountermeasures
Attacking The PlatformCisco
Patch Management is key – use the Cisco Voice Technology Group Subscription Tool (http://www.cisco.com/cgi-bin/Software/Newsbuilder/Builder/VOICE.cgi)
DoS and OS ExploitationCountermeasures
Attacking The PlatformCisco
Eavesdropping and Interception Countermeasures: Enable port security on Cisco Switches to help mitigate ARP
Spoofing Enable Dynamic ARP inspection to thwart ARP Spoofing Dynamically restrict Ethernet port access with 802.1x port
authentication Enable DHCP Snooping to prevent DHCP Spoofing Configure IP source guard on Switches
Eavesdropping and InterceptionCountermeasures
Attacking The PlatformCisco
Eavesdropping and Interception Countermeasures: Configure VTP Transparent Mode Change the default Native VLAN Value to thwart VLAN
hopping Disable Dynamic Trunk Protocol (DTP) to thwart VLAN
Hopping
Eavesdropping and InterceptionCountermeasures
Attacking The PlatformCisco
Eavesdropping and Interception Countermeasures: Activate authentication and encryption of the signaling and
media streams Skinny over TLS SRTP Requires creating and distributing certificates on phones
Attacking The PlatformCisco Eavesdropping and Interception
Countermeasures
VoIP systems are vulnerable to application attacks against the various VoIP protocols
Attacks include: Fuzzing attacks Flood-based DoS Signaling and media manipulation
Attacking The ApplicationAttacking The Application
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
FuzzingIntroduction
Attacking The ApplicationFuzzing
INVITE sip:6713@192.168.26.180:6060;user=phone SIP/2.0Via: SIP/2.0/UDP 192.168.22.36:6060From: UserAgent<sip:6710@192.168.22.36:6060;user=phone>To: 6713<sip:6713@192.168.26.180:6060;user=phone>Call-ID: 96561418925909@192.168.22.36Cseq: 1 INVITESubject: VovidaINVITEContact: <sip:6710@192.168.22.36:6060;user=phone>Content-Type: application/sdpContent-Length: 168
Attacking The ApplicationFuzzingFuzzing
Example
INVITE sip:6713@192.168.26.180:6060;user=phone SIP/2.0Via: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa…From: UserAgent<sip:6710@192.168.22.36:6060;user=phone>To: 6713<sip:6713@192.168.26.180:6060;user=phone>Call-ID: 96561418925909@192.168.22.36Cseq: 1 INVITESubject: VovidaINVITEContact: <sip:6710@192.168.22.36:6060;user=phone>Content-Type: application/sdpContent-Length: 168
Attacking The ApplicationFuzzingFuzzing
Example
There are many public domain tools available for fuzzing: Protos suite Asteroid Fuzzy Packet NastySIP Scapy
FuzzingPublic Domain Tools
Attacking The ApplicationFuzzing
SipBomber SFTF SIP Proxy SIPp SIPsak
There are some commercial tools available: Beyond Security BeStorm Codenomicon MuSecurity Mu-4000 Security Analyzer Security Innovation Hydra Sipera Systems LAVA tools
FuzzingCommercial Tools
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
FuzzingCountermeasures
Attacking The ApplicationFuzzing
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
Attacking The ApplicationFlood-Based DoSFlood-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
Flood-Based DoSCountermeasures
Attacking The ApplicationFlood-Based DoS
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
Attacking The Application Sig/Media ManipulationSignaling/Media Manipulation
Introduction
Proxy
User
Proxy
Attacker
HijackedMedia
HijackedSession
User
Registration Manipulation Attacking The Application Sig/Media Manipulation
Inbound CallsAre Redirected
Attacker
Proxy Proxy
User
Attacker Sends“301/302 – Moved”
Message
User
Redirection Attacks Attacking The Application Sig/Media Manipulation
Attacker SendsBYE Messages
To UAs
Attacker
Proxy Proxy
User User
Session Teardown Attacking The Application Sig/Media Manipulation
Attacker Sendscheck-sync Messages
To UA
Attacker
Proxy Proxy
User User
IP Phone Reboot Attacking The Application Sig/Media Manipulation
Attacker SeesPackets And
Inserts/Mixes InNew Audio
Attacker
Proxy Proxy
User User
Audio Insertion/Mixing 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
Attacking The Application Sig/Media ManipulationSignaling/Media Manipulation
Countermeasures
There are a couple of evolving social threats that will affect enterprises: Voice SPAM or SPAM over Internet Telephony (SPIT) Voice phishing
Social AttacksSocial Attacks
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
Voice SPAMIntroduction
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 can’t 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 isn’t any capability in the protocols that looks like it will
address Voice SPAM
Voice SPAM 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
Voice SPAMCountermeasures
Social AttacksVoice SPAM
VoIP PhishingIntroduction
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
Social AttacksPhishing
VoIP PhishingExample
“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.
Social AttacksPhishing
VoIP PhishingExample
Social AttacksPhishing
VoIP PhishingCountermeasuresTraditional email spam/phishing
countermeasures come in to play here.Educating users is a key
Social AttacksPhishing