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    Bluetooth – Security

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    1 Bluetooth
    2 Wireless- History
    3 Wireless- Technologies
    4 Bluetooth- Technical Introduction
    5 Bluetooth- Advantages
    6 Bluetooth- Applications
    7 Bluetooth- Security Issues
    7.1 The SNARF attack
    7.2 The BACKDOOR attack
    7.3 The BLUEBUG attack
    7.4 Bluejacking
    7.5 Warnibbling
    8 Future of Bluetooth
    9 See also:
    10 Reference List


    Bluetooth is a new technology that utilises radio frequency waves as a way to communicate wirelessly between digital devices. It sets up personal area networks that incorporate all of a persons digital devices into one system for both convergence and convenience.

    Wireless- History

    Many people put the invention of [wireless] radio down to Guglielmo Marconi, who in 1895 sent the first radio telegraph transmission across the English Channel. Only twelve years later radio began being used in the public sphere. [Mathias, p.2] Up until then however, many wireless pioneers conducted trials across lakes where the antenna used to transmit the signal was longer than the distance across the lake. [Brodsky, p. 3] After its introduction the main use of wireless radio was for military communications where its first use was for the Boer War. [Flichy, p. 103] The invention of broadcast radio ensured the feasibility of wireless technologies. [Morrow, p. 2] By the 1920s, radio had become a well-recognised mass medium. [Flichy, p. 111] From the 1980s until now, wireless communications have been through several stages, from 1G (analogue signal), 2G (digital signal) and 3G (always on, faster data rate). [Lightman and Rojas, p. 3] The history of Bluetooth is a much more recent one, with the first Bluetooth-enabled products coming into existence in 2000. Named after Harald Blatand the first, king of Denmark around twelve hundred years ago, who joined the Danish and Norwegian kingdoms, Bluetooth technology is founded on this same unifying principle of being able to unite the computer and telecommunication industr[ies]. [Ganguli, p. 5] In 1994 the Ericsson Company began looking into the idea of replacing cables connecting accessories to mobile phones and computers with wireless links, and this became the main inspiration behind Bluetooth. [Morrow, p. 10]

    Wireless- Technologies

    Bluetooth is not the only wireless technology currently being developed and utilised. Other wireless technologies, including 802.11b, otherwise known as Wi-Fi, Infrared Data Association (IrDA), Ultra- Wideband Radio (UWB), and Home RF are being applied to similar technologies that Bluetooth use with mixed results. 802.11 is the most well known technology, excluding Bluetooth, and uses the same radio frequency, meaning that they are not compatible as they cause interference with each other. 802.11 is being implemented into universities in the US, Japan and China, as well as food and beverage shops where they are being used to identify students and customers. Even airports have taken up the 802.11 technology, with airports all over America, and three of Americas most prominent airlines promoting the use of it. [Lightman and Rojas, p. 202-3] Infrared Data Association is extremely inferior to that of Bluetooth. Its limitations include only being able to communicate point-to-point, needing a line of sight, and it has a speed of fifty- six kilobytes per second, whereas Bluetooth is one megabyte per second. [Ganguli, p. 17] The Ultra- Wideband Radio is superior to that of Bluetooth in that it can transmit at greater lengths (up to 70 metres), with only half of the power that Bluetooth uses. [Ganguli, p.17] HomeRF is a technology that is not very well known. It is used for data and voice communication and targeted for the residential market segment and does not serve enterprise- class WLANs, public access systems or fixed wireless Internet access. [Ganguli, p.17-18]

    Bluetooth- Technical Introduction

    Bluetooth is a short- range radio device that replaces cables with low power radio waves to connect electronic devices, whether they are portable or fixed. The Bluetooth device also uses frequency hopping to ensure a secure, quality link, and it uses ad hoc networks, meaning that it connects peer-to-peer. It can be operated worldwide and without a network because it uses the unlicensed Industrial- Scientific Medical (ISM) band for transmission that varies with a change in location. [Ganguli, p. 25-6] The Bluetooth user has the choice of point-to-point or point-to-multipoint links whereby communication can be held between two devices, or up to eight. [Ganguli, p. 96] When devices are communicating with each other they are known as piconets, and each device is designated as a master unit or slave unit, usually depending on who initiates the connection. However, both devices have the potential to be either a master or a slave. [Swaminatha and Elden, p. 49]

    Bluetooth- Advantages

    There are many advantages to using Bluetooth wireless technologies including the use of a radio frequency, the inexpensive cost of the device, replacing tedious cable connections, the low power use and implemented security measures. The use of an unlicensed radio frequency ensures that users do not need to gain a license in order to use it. Unlike Infrared which needs to have a line of sight in order to work, Bluetooth radio waves are omnidirectional and do not need a clear path. The device itself is relatively cheap and easy to use, one can be bought for around ten American dollars, and this price is currently decreasing. Compare this to the expensive cost of implementing hundreds of cables and wires into an office and there is no competition. Of course, this is the main reason for the take -up in Bluetooth -enabled devices; it does away with cables. Another of Bluetooths advantages is its low power use, ensuring that battery operated devices such as mobile phones and personal digital assistants wont have their battery life drained with the use of it. This low power consumption also guarantees minimal interruption from other radio operated and wireless devices that operate at a higher power. Bluetooth has several enabled security measures that ensures a level of privacy and security, including frequency hopping, whereby the device changes radio frequency sixteen hundred times per second. Also within the security tools are encryption and authentification mechanisms that guarantee little interference by unauthorised hackers. [Ganguli, p. 330] One of the best advantages of Bluetooth devices, especially the hands free device that connects to a mobile phone, is that it removes radiation from the brain region. [Tsang, p.1]

    Bluetooth- Applications

    The applications that are in development or current use for the Bluetooth technology include such areas as automotive, medical, industrial equipment, output equipment, digital -still cameras, computers, and communications systems. [Lightman and Rojas, p. 201] Bluetooth is an ad hoc network user, and therefore it may be used for social networking, i.e. people can meet and share files or link their Bluetooth devices together to play games or other such activities. [Smyth, p. 70] Using Bluetooth, a mobile phone can become a three- way phone, where at home it connects to a landline for cheaper calls, on the move it acts as a mobile phone and when it comes in contact with another Bluetooth-enabled phone it acts as a walkie- talkie. This walkie- talkie option allows for free interaction and communication, as Bluetooth is not connected to any telecommunications network. [Gupta, p.1] Bluetooth also allows automatic synchronization of your desktop, mobile computer, notebook and your mobile phone for the user to have all of their data managed as one. [Gupta, p.1]

    Bluetooth- Security Issues

    Bluetooth has several threats which range in level of risk and how widespread the action is. These threats have the ability to provide criminals with sensitive information on both corporate and personal levels. The only way to avoid such threats is for manufacturers, distributors, and consumers to be provided with more information on how they are committed, current attack activity and how to combat them. This information can be used on a technical level for manufacturers, it can be used by distributors at retail levels to teach consumers the risks and it can be used directly by consumers to be aware of the threats. The outcome of such research will allow end users of Bluetooth products to have an upper hand in this wireless warfare. Bluetooth security is in early stages with regards to both the attackers, their techniques and consumers understanding of these attacks. Some research has been conducted into what the attackers are doing and how they do it. Adam Laurie of A.L Digital Ltd is leading the research race in Bluetooth security and is often linked to academic resources. Laurie’s research has uncovered the following capabilities of Bluetooth attacks:

    • Confidential data such as the entire phone book, calender and the phone’s IMEI.
    • Complete memory contents of some mobile phones can be accessed by a previously trusted (“paired”) device that has since been removed from the trusted list.
    • Access can be gained to the AT command set of the device, giving full access to the higher level commands and channels, such as data, voice and messaging.

    Attacks on Bluetooth devices at this stage are relatively new to consumers, and therefore are not widely seen as a real threat. Attacks such as the Bluejack attack are probably more recognised by consumers due to its perceived humorous and novelty nature as well as the ease to Bluejack someone. Users who allow their phone to be Bluejacked open the door to more serious attacks, such as the Backdoor attack which have a low level of awareness amongst consumers as attackers can attach to the device with out the users knowledge. Corporations are starting to understand the risks Bluetooth devices pose, Michael Ciarochi (in Brewin 2004) stated that ‘Bluetooth radios were included in laptop PCs that were being configured by an IT Engineer. It raises the possibility of opening a wireless back door into data stored on the PCs. Such a security weakness would be extremely attractive to hackers. Although Bluetooth invites hackers to such attacks; Bluetooth Venders are playing down the risks, Brewin (2004) said that ‘Bluetooth advocates last week dismissed growing security fears about the short-range wireless technology, saying any flaws are limited to a few mobile-phone models. They also detailed steps that users can take to secure Bluetooth devices’. There are many methods of Bluetooth attacks, the Snarf, the Backdoor, Bluebug, Bluejack and Warnibbling attack are the only recognised attacks at this early stage. Below are explanations of such attacks.

    The SNARF attack

    It is possible for attackers to connect to the device without alerting the user, once in the system sensitive data can be retrieved, such as the phone book, business cards, images, messages and voice messages.

    Local Copy: BlueSnarf_CeBIT2004.pdf

    The BACKDOOR attack

    The backdoor attack is a higher concern for Bluetooth users; it allows attackers to establishing a trust relationship through the “pairing” mechanism, but ensuring that the user can not see the target’s register of paired devices. In doing this attackers have access to all the data on the device, as well as access to use the modem or internet; WAP and GPRS gateways may be accessed without the owner’s knowledge or consent.

    The BLUEBUG attack

    This attack gives access to the AT command set, in other words it allows the attacker to make premium priced phone calls, allows the use of SMS, or connection the internet. Attackers can not only use the device for such fraudulent exercises it also allows identity theft to impersonate the user.


    Dibble (2004) explained that ‘Just as SMS was spawned, there’s a new craze that’s spreading across parts of Europe. Reportedly, it’s more prominent in the UK, but popular elsewhere too’. Bluejacking allows attackers to send messages to strangers in public via Bluetooth. When the phones ‘pair’ the attacked can write a message to the user. Although it may seem harmless at first, there is a downside. Once connected the attacker may then have access to any data on the users Bluetooth device, which has obvious concerns. Powell (2004: 22) explained that ‘Users can refuse any incoming message or data, so Bluejackers change their username to a short barb or compliment to beat you to the punch. For example, you might receive something along the lines of “Incoming message from: Dude, you’ve been Bluejacked.” Or, “Incoming message from: ROI is overrated.” Bluejacking is regarded as a smaller threat to Bluetooth as users being attacked are aware they have been Bluejacked. This does not mean however that they are aware that sensitive information is being accessed and used in a malicious manner.


    Warnibbling is a hacking technique using Redfang, or similar software that allows hackers to reveal corporate or personal sensitive information. Redfang allows hackers to find Bluetooth devices in the area, once found, the software takes you through the process of accessing any data that is stored on that device. Redfang also allows non-discoverable devices to be found. Whitehouse explains when testing Redfang ‘One of the first obstacles we had to overcome was the discovery of non-discoverable devices (it was surprising to see the number of devices that dont by default implement this security measure)’.

    Future of Bluetooth

    Further information, and somewhat speculation is required for consumers and Bluetooth stakeholders on the future of Bluetooth. Such information will provide a clearer understanding of why security of Bluetooth must be improved. Luo and Lee (2004) provide a short term prediction of where Bluetooth is heading, Europe and Asian countries already offer electronic newspapers, subway tickets, and car parking fees via wireless devices. Collins (2003) says that Bluetooth devices ‘appear to be more secure than 802.11 wireless LANs. However, this situation may not last, as the Bluetooth technology becomes more widespread and attracts greater interest from the hacking community’.

    See also:

    Reference List

    • Brodsky, I. (1995) Wireless: The Revolution in Personal Telecommunications, Massachussetts, USA: Artech House Inc, ISBN 0890067171 (Erin Watson)
    • Collins, G. (2003) Bluetooth Security. [Online], Available: Academic Search Elite, ISSN:0360-5280 [Accessed 6/9/04]. (Ben Henzell)
    • Dibble, T (2003) ‘Bluejack city: a new wireless craze is spreading through Europe’ [Online]. Available: [Accessed 4/8/04. (Ben Henzell)
    • Finn, E. (2004) Be carefull when you cut the cord. Popular Science [Online], vol. 264, issue. 5, p30. Available: Ebsco Host: Academic Search Elite, ISSN:0161-7370 [Accessed 6/9/04]. (Ben Henzell)
    • Flichy, P. (1995) Dynamics of Modern Communication, London: Sage Publications, ISBN 0803978502 (Erin Watson)
    • Ganguli, M. (2002) Getting Started with Bluetooth, Ohio: Premier Press, ISBN 1931841837 (Erin Watson)
    • Gupta, P. 1999. Bluetooth Technology: What are the Applications?. (accessed August 23, 2004). (Erin Watson)
    • Laurie, B & L (2003) Serious flaws in Bluetooth security lead to disclosure of personal data [Online]. Available: [Accessed 4th Aug 2004]. (Ben Henzell)
    • Lightman, A. and Rojas, W. (2002) Brave New Unwired World, New York, USA: John Wiley and Sons, Inc., ISBN 0471441104 (Erin Watson)
    • Luo, X. Lee, C. (2004). Micropayments in Wireless M-Commerce: Issues, Security, and Trend[Online]. Available: [Accessed 4/8/2004] (Ben Henzell)
    • Morrow, R. (2002) Bluetooth Operation and Use, New York, USA: The McGraw- Hill Companies, ISBN 007138779X (Erin Watson)
    • Powell, W. (2004) The Wild Wild Web T+D [Online], Vol. 58, issue. 1, p22. Available: Academic Search Elite, ISSN:1535-7740 [Accessed 6/9/04]. (Ben Henzell)
    • Smyth, P. (ed.)(2004) Mobile and Wireless Communications: Key Technologies and Future Applications, London, UK: The Institute of Electrical Engineers, ISBN 0863413684 (Erin Watson)
    • Swaminatha, T. and Elden, C. (2003) Wireless Security and Privacy: Best Practices and Design Techniques, Massachussetts, USA: Pearson Education, Inc., ISBN 0201760347 (Erin Watson)
    • Tsang, W. et al. Date unknown. Bluetooth Applications. (accessed August 23, 2004). (Erin Watson)
    • Whitehouse, O. (2003).’War Nibbling: Bluetooth Insecurity’ [Online]. Available: [Accessed 9/8/04] (Ben Henzell)

    Erin Watson 08:47, 8 Sep 2004 (EST) –nhenzell 12:30, 8 Sep 2004 (EST)

    Serious flaws in bluetooth security lead to disclosure of personal data




    In November 2003, Adam Laurie of A.L. Digital Ltd. discovered that there are serious flaws in the authentication and/or data transfer mechanisms on some bluetooth enabled devices. Specifically, three vulnerabilities have been found:

    Firstly, confidential data can be obtained, anonymously, and without the owner’s knowledge or consent, from some bluetooth enabled mobile phones. This data includes, at least, the entire phone book and calendar, and the phone’s IMEI.

    Secondly, it has been found that the complete memory contents of some mobile phones can be accessed by a previously trusted (“paired”) device that has since been removed from the trusted list. This data includes not only the phonebook and calendar, but media files such as pictures and text messages. In essence, the entire device can be “backed up” to an attacker’s own system.

    Thirdly, access can be gained to the AT command set of the device, giving full access to the higher level commands and channels, such as data, voice and messaging. This third vulnerability was identified by Martin Herfurt, and they have since started working together on finding additional possible exploits resulting from this vulnerability.

    Finally, the current trend for “Bluejacking” is promoting an environment which puts consumer devices at greater risk from the above attacks.

    The SNARF attack:
    It is possible, on some makes of device, to connect to the device without alerting the owner of the target device of the request, and gain access to restricted portions of the stored data therein, including the entire phonebook (and any images or other data associated with the entries), calendar, real-time clock, business card, properties, change log, IMEI (International Mobile Equipment Identity [6], which uniquely identifies the phone to the mobile network, and is used in illegal phone ‘cloning’). This is normally only possible if the device is in “discoverable” or “visible” mode, but there are tools available on the Internet that allow even this safety net to be bypassed[4]. Further details will not be released at this time (see below for more on this), but the attack can and will be demonstrated to manufacturers and press if required.

    The BACKDOOR attack:
    The backdoor attack involves establishing a trust relationship through the “pairing” mechanism, but ensuring that it no longer appears in the target’s register of paired devices. In this way, unless the owner is actually observing their device at the precise moment a connection is established, they are unlikely to notice anything untoward, and the attacker may be free to continue to use any resource that a trusted relationship with that device grants access to (but note that so far we have only tested file transfers). This means that not only can data be retrieved from the phone, but other services, such as modems or Internet, WAP and GPRS gateways may be accessed without the owner’s knowledge or consent. Indications are that once the backdoor is installed, the above SNARF attack will function on devices that previously denied access, and without the restrictions of a plain SNARF attack, so we strongly suspect that the other services will prove to be available also.

    The BLUEBUG attack:
    The bluebug attack creates a serial profile connection to the device, thereby giving full access to the AT command set, which can then be exploited using standard off the shelf tools, such as PPP for networking and gnokii for messaging, contact management, diverts and initiating calls. With this facility, it is possible to use the phone to initiate calls to premium rate numbers, send sms messages, read sms messages, connect to data services such as the Internet, and even monitor conversations in the vicinity of the phone. This latter is done via a voice call over the GSM network, so the listening post can be anywhere in the world. Bluetooth access is only required for a few seconds in order to set up the call. Call forwarding diverts can be set up, allowing the owner’s incoming calls to be intercepted, either to provide a channel for calls to more expensive destinations, or for identity theft by impersonation of the victim.

    Although known to the technical community and early adopters for some time, the process now known as “Bluejacking”[1] has recently come to the fore in the consumer arena, and is becoming a popular mechanism for exchanging anonymous messages in public places. The technique involves abusing the bluetooth “pairing”[2] protocol, the system by which bluetooth devices authenticate each other, to pass a message during the initial “handshake” phase. This is possible because the “name” of the initiating bluetooth device is displayed on the target device as part of the handshake exchange, and, as the protocal allows a large user defined name field – up to 248 characters – the field itself can be used to pass the message. This is all well and good, and, on the face of it, fairly harmless, but, unfortunately, there is a down side. There is a potential security problem with this, and the more the practice grows and is accepted by the user community, and leveraged as a marketing tool by the vendors, the worse it will get. The problem lies in the fact that the protocol being abused is designed for information exchange. The ability to interface with other devices and exchange, update and synchronise data, is the raison d’être of bluetooth. The bluejacking technique is using the first part of a process that allows that exchange to take place, and is therefore open to further abuse if the handshake completes and the “bluejacker” successfully pairs with the target device. If such an event occurs, then all data on the target device becomes available to the initiator, including such things as phone books, calendars, pictures and text messages. As the current wave of PDA and telephony integration progresses, the volume and quality of such data will increase with the devices’ capabilities, leading to far more serious potential compromise. Given the furore that irrupted when a second-hand Blackberry PDA was sold without the previous owner’s data having been wiped[3], it is alarming to think of the consequences of a single bluejacker gathering an entire corporate staff’s contact details by simply attending a conference or camping outside their building or in their foyer with a bluetooth capable device and evil intent. Of course, corporates are not the only potential targets – a bluejacking expedition to, say, The House of Commons, or The US Senate, could provide some interesting, valuable and, who’s to say, potentially damaging or compromising data.<<<


    The above may sound alarmist and far fetched, and the general reaction would probably be that most users would not be duped into allowing the connection to complete, so the risk is small. However, in today’s society of instant messaging, the average consumer is under a constant barrage of unsolicited messages in one form or another, whether it be by SPAM email, or “You have won!” style SMS text messages, and do not tend to treat them with much suspicion (although they may well be sceptical about the veracity of the offers). Another message popping up on their ‘phone saying something along the lines of “You have won 10,000 pounds! Enter this 4 digit PIN number and then dial 0900-SUCKER to collect your prize!” is unlikely to cause much alarm, and is more than likely to succeed in many cases.

    Workarounds and fixes
    We are not aware of any workarounds for the SNARF or BLUEBUG attacks at this time, other than to switch off bluetooth. For permanent fixes, see the ‘Fixes’ section at the bottom of the page.

    To permanently remove a pairing, and protect against future BACKDOOR attacks, it seems you must perform a factory reset, but this will, of course, erase all your personal data.

    To avoid Bluejacking, “just say no”. :)

    The above methods work to the best of our knowledge, but, as the devices affected are running closed-source proprietary software, it not possible to verify that without the collaboration of the manufacturers. We therefore make no claims as to the level of protection they provide, and you must continue to use bluetooth at your own risk.

    Who’s Vulnerable
    To date the quantity of devices tested is not great. However, due to the fact that they are amongst the most popular brands, we still consider the affected group to be large. It is also assumed that there are shared implementations of the bluetooth stack, so what affects one model is likely to affect others. This table is accurate to the best of our knowledge, but without the cooperation of the manufacturers (which we currently do not have), it is not possible to conduct more extensive validation.

    The devices known to be vulnerable at this time are:

    Vulnerability Matrix (* = NOT Vulnerable)
    MakeModelFirmware RevBACKDOORSNARF when VisibleSNARF when NOT VisibleBUG
    Sony EricssonR520m20R2G?YesNo?
    Sony EricssonT68i20R1B
    Sony EricssonT61020R1A081
    Sony EricssonT61020R1A081???Yes
    Sony EricssonZ1010??Yes??
    Sony EricssonZ60020R2C007
    Nokia7650?YesNo (+)?No
    * SiemensS55?NoNoNoNo
    * SiemensSX1?NoNoNoNo
    MotorolaV600 (++)?NoNoNoYes
    MotorolaV80 (++)?NoNoNoYes

    + We now believe the 7650 is only vulnerable to SNARF if it has already been BACKDOORed.
    ++ The V600 and V80 are discoverable for only 60 seconds, when first powered on or when this feature is user selected, and the window for BDADDR discovery is therefore very small. Motorola have stated that they will correct the vulnerability in current firmware.

    What is the Philosophy of Full Disclosure, and why are we providing the tools and detailing the methods that allow this to be done? The reasoning is simple – by exposing the problem we are achieving two goals: firstly, to alert users that the dangers exist, in order that they can take their own precautions against compromise, and secondly, to put pressure on manufacturers to rectify the situation. Consumers have a right to expect that their confidential data is treated as such, and is not subject to simple compromise by poorly implemented protocols on consumer devices. Manufacturers have a duty of care to ensure that such protection is provided, but, in practice, commercial considerations will often take precedence, and, given the choice, they may choose to simply supress or hide the problem, or, even worse, push for laws that prevent the discovery and/or disclosure of such flaws[5]. In our humble opinion, laws provide scant consumer protection against the lawless.

    After 13 months, and in consideration of the fact that affected manufacturers had acknowledged the issues and made updated firmware available, Full Disclosure took place at the Chaos Computer Club’s annual congress – 21C3, in Berlin, 2004.

    Slides from the disclosure talk can be found here:

    Proof of concept utilities have been developed, but are not yet available in the wild. They are:

    • bluestumbler – Monitor and log all visible bluetooth devices (name, MAC, signal strength, capabilities), and identify manufacturer from MAC address lookup.
    • bluebrowse – Display available services on a selected device (FAX, Voice, OBEX etc).
    • bluejack – Send anoymous message to a target device (and optionally broadcast to all visible devices).
    • bluesnarf – Copy data from target device (everything if pairing succeeds, or a subset in other cases, including phonebook and calendar. In the latter case, user will not be alerted by any bluejack message).
    • bluebug – Set up covert serial channel to device.
      Tools will not be released at this time, so please do not ask. However, if you are a bona-fide manufacturer of bluetooth devices that we have been otherwise unable to contact, please feel free to get in touch for more details on how you can identify your device status.

    The above vulnerabilities were discovered by Adam Laurie, during the course of his work with A.L. Digital, in November 2003, and this announcement was prepared thereafter by Adam and Ben Laurie for immediate release.

    Adam Laurie is Managing Director and Chief Security Officer of A.L. Digital Ltd.

    Ben Laurie is Technical Director of A.L. Digital, and author of Apache-SSL and contributor to many other open source projects, too numerous to expand on here.

    A.L. Digital Ltd. are the owner operators of The Bunker, the world’s most secure data centre(s).


    Further information relating to this disclosure will be updated at






    • bluesniff
    • btscanner
    • redfang