Sicurezza trasmissione
FAQ
Differenze
tra nfc e bluetooth
Although the communication range of NFC is limited to a few centimeters, NFC alone does not ensure secure communications. In 2006, Ernst Haselsteiner and Klemens Breitfuß described different possible types of attacks, and detail how to leverage NFC's resistance to Man-in-the-middle attacks to establish a specific key.[20] Unfortunately, as this technique is not part of the ISO standard, NFC offers no protection against eavesdropping and can be vulnerable to data modifications. Applications may use higher-layer cryptographic protocols (e.g., SSL) to establish a secure channel. Ensuring security for NFC data will require the cooperation of multiple parties: device providers, who will need to safeguard NFC-enabled phones with strong cryptography and authentication protocols; customers, who will need to protect their personal devices and data with passwords, keypad locks, and anti-virus software; and application providers and transaction parties, who will need to use anti-virus and other security solutions to prevent spyware and malware from infecting systems.[21]
[edit]Eavesdropping
The RF signal for the wireless data transfer can be picked up with antennas. The distance from which an attacker is able to eavesdrop the RF signal depends on numerous parameters, but is typically a small number of metres.[22] Also, eavesdropping is extremely affected by the communication mode. A passive device that doesn't generate its own RF field is much harder to eavesdrop on than an active device. One Open source device that is able to eavesdrop on passive and active NFC communications is the Proxmark instrument.
[edit]Data modification
It is relatively easy to destroy data by using an RFID jammer. There is no way currently to prevent such an attack. However, if NFC devices check the RF field while they are sending, it is possible to detect attacks.
It is much more difficult to modify data in such a way that it appears to be valid to users. To modify transmitted data, an intruder has to deal with the single bits of the RF signal. The feasibility of this attack, (i.e., if it is possible to change the value of a bit from 0 to 1 or the other way around), is amongst others subject to the strength of the amplitude modulation. If data is transferred with the modified Miller coding and a modulation of 100%, only certain bits can be modified. A modulation ratio of 100% makes it possible to eliminate a pause of the RF signal, but not to generate a pause where no pause has been. Thus, only a 1 which is followed by another 1 might be changed. Transmitting Manchester-encoded data with a modulation ratio of 10% permits a modification attack on all bits.
[edit]Relay attack
Because NFC devices usually include ISO/IEC 14443 protocols, the relay attacks described are also feasible on NFC.[23][24] For this attack the adversary has to forward the request of the reader to the victim and relay back its answer to the reader in real time, in order to carry out a task pretending to be the owner of the victim’s smart card. One of libnfc code examples demonstrates a relay attack using only two stock commercial NFC devices.
[edit]Lost property
Losing the NFC RFID card or the mobile phone will open access to any finder and act as a single-factor authenticating entity. Mobile phones protected by a PIN code acts as a single authenticating factor. A way to defeat the lost-property threat requires an extended security concept that includes more than one physically independent authentication factor.
[edit]Walk-off
Lawfully opened access to a secure NFC function or data is protected by time-out closing after a period of inactivity. Attacks may happen despite provisions to shutdown access NFC after the bearer has become inactive. The known concepts described primarily do not address the geometric distance of a fraudulent attacker using a lost communication entity against lawful access from the actual location of the registered bearer. Additional feature to cover such attack scenario dynamically shall make use of a second wireless authentication factor that remains with the bearer in case of lost NFC communicator. Relevant approaches are described as an electronic leash or its equivalent, a wireless key.
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