Wednesday, 21 January 2015


(Written By: Sandeep Sinha, PGDM PT 2012-2015)

Bluetooth defines three security modes. Security Mode 1 provides no security enforcement, meaning that the device is effectively taking no steps to protect itself. Security Mode 2 enforces security at the service level. In this mode, a particular application might be relatively safe but no additional device protection has been added. Security Mode 3 is the highest level of security, employing link level enforced security mechanisms. Security Mode 3 protects the device from certain intrusions and, therefore, all services and applications

All Bluetooth services have a default set level of security. Within the service level security, there are also three levels of security. Some services that require authorization and authentication in order to be used, some require authentication only, and some are open to all devices. Bluetooth devices themselves have two levels of security when describing other devices, namely trusted devices and untrusted devices.


There are a variety of attacks that can be employed against Bluetooth devices, many with colorful names such as blue bugging, blue bumping, blue dumping, blue jacking, blue smacking, blue sniffing, blue spoofing, blue stabbing, blue toothing, and car whisperer. All take advantage of weaknesses in Bluetooth that allow an attacker unauthorized access to a victim's phone. It is imperative to note that while Bluetooth is commonly associated with networks limited in scope to 100 m, attacks on Bluetooth devices have been documented at ranges in excess of 1,500 m. using Bluetooone.

One common approach to hacking Bluetooth devices is to employ malformed objects, which are legal files exchanged between BT devices that contain invalid information, thus causing unexpected results. When a Bluetooth device receives a malformed object, such as a vCard or vCal file, the device may become unstable or fail completely. Alternatively, an attacker might also use a vCard or vCal file to inject commands allowing the attacker to take control of the device. This kind of an attack can be very harmful to a phone.

Some of the common attacks on Bluetooth devices include:

     Bluebugging: An extraordinarily powerful attack mechanism, bluebugging allows an attacker to take control of a victim's phone using the AT command parser. Bluebug allows an attacker to access a victim's phone in order to make phone calls, send short message service (SMS) messages, read SMS messages stored on the phone, read and write contact list entries, alter phone service parameters, connect to the Internet, set call forwarding, and more.

     Bluejacking: The sending of unsolicited messages to open Bluetooth devices by sending a vCard with a message in the name field and exploiting the OBEX protocol.

     Bluesmack: A Bluetooth analog of the Ping-of-Death denial-of-service attack. This is a buffer overflow attack using L2CAP echo messages.

     Bluesnarf and Bluesnarf++: Attacks allowing for the theft of information from a Bluetooth device using the OBEX Push Profile. The attacker needs only find a phone that has Bluetooth in discoverable mode. Bluesnarf works by a connection to most of the Object Push Profile services and the attacker retrieves the file names of known files from the Infrared Mobile Communications (IrMC) list instead of sending vCard information as expected. With these attacks the hacker can retrieve items such as the phonebook, calendar, and other personal information. With Bluesnarf++, the attacker has full read and write access to the file system of the phone. When an attacker is connected via the OBEX Push Profile, he/she has full access to the victim's phone without having to pair the two devices. The biggest risk with this function is that an attacker can delete crucial file system files, rendering the victim's device useless. In addition, the attacker can access any memory cards that are attached to the device.

     Helomoto: Helomoto is functionally similar to the Bluebug attack but takes advantage of poor implementations of "trusted device" handling on some phones. As in bluebug attacks, the attacker pretends to send a vCard to an unauthenticated OBEX Push Profile on the victim's phone. Once started, the attacker interrupts the transfer process and the victim then lists the attacker’s phone as a trusted device. The attacker can then connect to the victim's phone and take control of the device by issuing AT commands. This attack is so-named because it was first discovered on Motorola phones.

These attacks are only a few that can be launched against Bluetooth interfaces in phones, laptops, and even automobiles. E-Stealth and Laurie et al. offer information about a wide range of attacks that can be launched via Bluetooth vulnerabilities.