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Security Requirements for Highly Mobile Devices. Bob Beach Symbol Technologies. Purpose. Focus on security requirements of highly mobile devices Distinguish them from PC based enterprise systems Also from Consumer/Home devices Describe general characteristics of such units
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Security Requirements for Highly Mobile Devices Bob Beach Symbol Technologies
Purpose • Focus on security requirements of highly mobile devices • Distinguish them from PC based enterprise systems • Also from Consumer/Home devices • Describe general characteristics of such units • How devices are used • How they are constructed • How organizations that use them operate • Present security requirements • Kerberos and HMD
What are Highly Mobile Devices (HMD)? • Devices include: • Data collection/entry terminals • Telephones • Mobile machines (e.g. robot/autonomous devices) • Embedded personal devices (Medical patient monitoring systems) • HMD were one of the original drivers for 802.11 • Lots of installed systems/units (just 802.11) • Symbol Technologies alone: 100,000 sites; 1M+ devices • Other vendors have similar installed user bases
HMD Attributes (1) • Application Oriented • Customized for environment and/or application • hardware, software, user interface • Not a general purpose device • Users are task oriented and the HMD is a tool for them • Relatively simple applications • Users: • retail clerks - warehouse workers - package sorting • hospital workers - transportation and logistics • prison guards - airline and hotel checkin - baggage handlers • law enforcement - manufacturing workers - stock traders
HMD Attributes (2) • Not A Personal Device • Owned by organization, not individual • Device does not leave the facility • A device may be used by many different individuals during a day • Individual may use device on shift or task basis • Little or no personal “connection to device” • no user specific data and few user options • Many devices are interchangeable • Expected to operate a shift on single battery charge • 8-10 hours • 1000’s of transactions in that time period
HMD Attributes (3) • Device/user moves frequently • Mobility is key reason for such existence of such devices • Roaming takes place often and for a variety of reasons • physical movement and/or load balancing between APs • Users expect transitions between APs to be undetected • Device Hardware • very limited performance CPU (a few MIPs) • limited memory (512KB to a few MB) • specialized keyboard/display • application oriented peripherals (bar code reader, audio, etc.) • WLAN interface integrated into device
HMD Attributes (4) • Device Software • Often simple OS • Unit boots to application • 1-3 applications • Software updated over network
Organizations that use HMDs • Not “office/enterprise” oriented • may have an office/enterprise element (headquarters) but primary business activity is not office oriented • Extreme variation in site configuration • Many sites or few very large sites • e.g. 4000 retail locations or three 4M sq ft warehouses • Often little or no onsite MIS knowledge • Network infrastructure is simple but sufficient • may be tied into organization network • HMDs are key to operation of business • if WLAN fails, the business stops
Organizations that use HMDs (2) • Wide variety of onsite servers • All variations of Unix • Windows NT (3.5 and 4.0) • Windows 2000 • Limited authentication facilities • User logins are at the application level, not device level • more for identification purposes than security • No dial-in access by employees (may be expressly forbidden) • No formal authentication servers
Voice HMDs • VOIP telephones using a variety of call setup protocols • H.323, SIP, proprietary • Voice signals are digitized, compressed, and packetized • G.729 produces a block of compressed voice every 10ms • Combine 2-4 blocks into one 802.11 packet (20-40ms) • Full duplex operation • One lost cell represents 20-40ms of voice which is detected by the user • Roaming is frequent and expected to be invisible • Roaming triggered by both signal and load considerations
Security Considerations (1) • For many organizations that use HMD, operation of WLAN is key to operation of business • if WLAN stops working, business stops • if information on network is damaged/destroyed, business stops • One major cause for a WLAN to stop working are due to security breaches • Prevent devices from attaching to real Access Points • Allow unauthorized devices to attach to network • may damage or destroy critical data • gain access to larger organization network
Security Considerations (2) • Systems must operate with little or no onsite support • Once system is installed, the goal is never to touch it • No one onsite to debug problems or deal with attacks • Remote support may be available • New devices added frequently due to damage/loss • Many sites are security “innocents” that may be completely unaware of security issues and/or possible attacks even when happening • Cost is major consideration for organizations with 1000’s of sites
Security Requirements • In some ways not very different than base Tgi requirements: • Mutual authentication of clients and APs • Per session encryption keys with key lifetime support • Improved encryption algorithms (but without any new hardware) • Some elements are more important for HMD than for PC/enterprise systems • Fast and frequent roaming • Limited capability clients • Large installed base of clients and APs
Kerberos and HMD (1) • Kerberos is well suited for HMD • Provides mutual authentication • Provides unique key distribution with key lifetime support • Limited demands on client and AP memory/CPU resources • implemented on 10 MHz 80188 CPU in less than 48K memory • Supports PC/Enterprise model as needed • e.g. supports both HMD and PCs • Provides fast roaming support
Kerberos and HMD (2) • Self contained protocol that does not require other protocols to meet goals (e.g. Certificates, IAPP, etc) • KDCs are available for most server configurations • “Issues” with Kerberos are not significant in most HMD sites • Username/Password may be selected for maximum security since they are stored on device and not entered by human user. • Yet any lost/stolen device can easily be blocked from network
Conclusions • HMD are widespread and are critical to the operation of many businesses • HMD are quite different from PC/enterprise model in what they are used for and who uses them • Any TGI proposal must take into account the needs of HMD • Kerberos is an excellent solution for HMD