Mitigating a resource use attack

Abstract

It is provided a method for mitigating a resource use attack by a transmitter device (1) against a receiver device (2) over a wireless interface (4). The method is performed by a receiver device (2). The method comprises: receiving (40) a header transmission from a transmitter device (1), the header (21) forming part of a radio frame (20), the header (21) comprising an indicator of size of a subsequent transmission of a payload (22) in the radio frame (20), wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; performing (42) a payload measurement, being a measurement of received signal strength measurement when the payload (22) of the radio frame (20) is expected to be received; determining (44) that the payload measurement is lower than a threshold; and releasing (46) resources used for receiving the payload.

Description

MITIGATING A RESOURCE USE ATTACKTECHNICAL FIELD

[0001] The present disclosure relates to the field of resource use attacks by transmitters over wireless interfaces, and in particular to mitigating, in a receiver device, a resource use attack by a transmitter device.BACKGROUND

[0002] In wireless communication, a receiver device listens for incoming communication. When such listening occurs for random access transmissions, there is a risk that a transmitter can exploit the random access to make receiver device waste resources. For instance, such a resource use attack can occur by an attacker with a transmitter device transmitting a radio frame only consisting of a header, where the header indicates that a long payload will be transmitted in the rest of the radio frame. The payload is then never transmitted.

[0003] The receiver device receives the header of the radio frame and then prepares to receive the payload of the radio frame. However, as described above, the attacker never transmits the payload. This results in wasted resources in the receiver when the receiver listens and attempts to decode received radio signals. The attacker can repeat the attack many times to cause accumulated wasted resources in the receiver.

[0004] There is currently no way for a receiver device to reduce the effects of such resource use attacks, while still being able to receive legitimate random access communication.SUMMARY

[0005] One object is to provide a way to detect and mitigate resource use attacks against receiver devices over a wireless interface.

[0006] In some aspects, the embodiments described herein relate to a method for mitigating a resource use attack by a transmitter device against a receiver device over a wireless interface, the method being performed by a receiver device, the method comprising: receiving a header transmission from a transmitter device, the headerforming part of a radio frame, the header comprising an indicator of size of a subsequent transmission of a payload in the radio frame, wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; performing a payload measurement, being a measurement of received signal strength measurement when the payload of the radio frame is expected to be received, wherein the expectation of when the payload is to be received is based on the size indicated in the header; determining that the payload measurement is lower than a threshold; and releasing resources used for receiving the payload.

[0007] In some aspects, the embodiments described herein relate to a method, wherein the performing payload measurement is repeated for a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount.

[0008] In some aspects, the embodiments described herein relate to a method wherein the releasing resources comprises ending attempts to decode the payload.

[0009] In some aspects, the embodiments described herein relate to a method, wherein the releasing resources comprises setting the receiver device in a state where it is ready to receive a new header.

[0010] In some aspects, the embodiments described herein relate to a method, wherein the wireless interface is a short-range wireless interface.

[0011] In some aspects, the embodiments described herein relate to a method, wherein the wireless interface complies with any communication standard in accordance with Institute of Electrical and Electronics Engineers, IEEE, 802.15.4.

[0012] In some aspects, the embodiments described herein relate to a method, wherein the wireless interface complies with Bluetooth, Bluetooth low energy, BLE or Z- Wave.

[0013] In some aspects, the embodiments described herein relate to a method, wherein the threshold is determined in relation to the header measurement.

[0014] In some aspects, the embodiments described herein relate to a method, wherein the threshold is a static value.

[0015] In some aspects, the embodiments described herein relate to a receiver device for mitigating a resource use attack by a transmitter device against the receiver device over a wireless interface, the receiver device comprising: processing circuitry; and memory circuitry storing instructions that, when executed by the processing circuitry, cause the receiver device to: receive a header transmission from a transmitter device, the header forming part of a radio frame, the header comprising an indicator of size of a subsequent transmission of a payload in the radio frame, wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; perform a payload measurement, being a measurement of received signal strength measurement when the payload of the radio frame is expected to be received, wherein the expectation of when the payload is to be received is based on the size indicated in the header; determine that the payload measurement is lower than a threshold; and release resources used for receiving the payload.

[0016] In some aspects, the embodiments described herein relate to a receiver device, further comprising instructions that, when executed by the processing circuitry, cause the content receiver device to repeat the payload measurement a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount.

[0017] In some aspects, the embodiments described herein relate to a In some aspects, the embodiments described herein relate to a receiver device, wherein the instructions to release resources comprise instructions that, when executed by the processing circuitry, cause the content receiver device to end attempts to decode the payload.

[0018] In some aspects, the embodiments described herein relate to a receiver device, wherein the instructions to release resources comprises instructions that, when executed by the processing circuitry, cause the content receiver device to set the receiver device in a state where it is ready to receive a new header.

[0019] In some aspects, the embodiments described herein relate to a receiver device, wherein the wireless interface is a short-range wireless interface.

[0020] In some aspects, the embodiments described herein relate to a receiver device, wherein the wireless interface complies with any communication standard in accordance with Institute of Electrical and Electronics Engineers, IEEE, 802.15.4.

[0021] In some aspects, the embodiments described herein relate to a receiver device, wherein the wireless interface complies with Bluetooth, or Bluetooth low energy, BLE.

[0022] In some aspects, the embodiments described herein relate to a receiver device, wherein the threshold is determined in relation to the header measurement.

[0023] In some aspects, the embodiments described herein relate to a receiver device, wherein the threshold is a static value.

[0024] In some aspects, the embodiments described herein relate to a computer program for mitigating a resource use attack by a transmitter device against a receiver device over a wireless interface, the computer program comprising computer program code which, when executed on a receiver device causes the receiver device to: receive a header transmission from a transmitter device, the header forming part of a radio frame, the header comprising an indicator of size of a subsequent transmission of a payload in the radio frame, wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; perform a payload measurement, being a measurement of received signal strength measurement when the payload of the radio frame is expected to be received, wherein the expectation of when the payload is to be received is based on the size indicated in the header; determine that the payload measurement is lower than a threshold; and release resources used for receiving the payload.

[0025] In some aspects, the embodiments described herein relate to a computer program product comprising the computer program according and a computer readable means comprising non-transitory memory in which the computer program is stored.

[0026] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Aspects and embodiments are now described, by way of example, with reference to the accompanying drawings, in which:

[0028] Fig 1 is a schematic diagram illustrating an environment in which embodiments presented herein can be applied;

[0029] Fig 2 is a schematic diagram illustrating a structure of a radio frame that can be applied in the environment of Fig 1;

[0030] Figs 3A-B are schematic graphs illustrating signal strengths for a normal radio frame and a radio frame of an attacker;

[0031] Fig 4 is a flow chart illustrating methods for mitigating a resource use attack by a transmitter device against a receiver device over a wireless interface;

[0032] Fig 5 is a schematic diagram illustrating components of the receiver device of Fig 1; and

[0033] Fig 6 shows one example of a computer program product comprising computer readable means.DETAILED DESCRIPTION

[0034] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, theseembodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of invention to those skilled in the art. Like numbers refer to like elements throughout the description.

[0035] According to embodiment presented herein, a resource use attack over a wireless interface is detected by a receiver device by detecting that a received signal level drops off after the header has been received, when an indicated payload is supposed to be received. When the resource use attack is detected, resources for receiving the payload is released, thereby effectively reducing the effect on such a resource use attack.

[0036] Fig 1 is a schematic diagram illustrating an environment in which embodiments presented herein can be applied. A receiver device 2 is a device capable of receiving short-range communication for any suitable purpose over a wireless interface 4. The wireless interface 4 can thus be a short-range communication interface e.g. comply with any communication standard in accordance with Institute of Electrical and Electronics Engineers (IEEE) 802.15.4, such as Thread, ZigBee, WirelessHART, Matter, etc. Alternatively or additionally, the wireless interface 4 complies with Bluetooth, Bluetooth low energy (BLE) or Z-wave. The short-range communication interface can be an interface that supports local point-to-point communication, which is optionally extendible to mesh networks. It is to be noted that the receiver device 2 can also act as a transmitter, but for purposes herein, the receiver device 2 is described in its capability of receiving short-range wireless communication, and how an attacker with a transmitter device 1 can exploit the wireless interface 4 for a resource use attack.

[0037] The receiver device 2 listens for the transmitter device 1 to initiate communication over the wireless interface 4. It is to be noted that the wireless interface 4 supports random access in that the transmitter device 1 can initiate communication 1 that the receiver device 2 will receive and process, without the receiver device 2 informing the transmitter device 1 that it is allowed to transmit.

[0038] Fig 2 is a schematic diagram illustrating a structure of a radio frame 20 that can be applied in the environment of Fig 1. The radio frame 20 comprises a header 21 and a payload 22. The header 21 comprises, among other fields (not shown), an indicator 23 of size of a subsequent transmission of the payload 22. The payload 22 canbe much larger than the header 21. Purely as an illustration, e.g. in Zigbee, the header is one byte long and the payload is 3 - 127 bytes long.

[0039] Figs 3A-B are schematic graphs illustrating signal strength for a normal radio frame and a radio frame of an attacker. The horizontal axis indicates time and the vertical axis 15 indicates signal strength, e.g. as a received signal strength indicator (RSSI) at the receiver side, e.g. received by the receiver device 2. Between times to and ti, a header is received. Between times ti and t2, a payload, the size of which being indicated in the header, is supposed to be received.

[0040] In Fig 3A, a normal signal strength curve 10 for a normal radio frame is shown. The normal signal strength curve 10 remains high for the entire duration of the radio frame, both during the header reception (time to - ti) and during the payload reception (time ti - 12).

[0041] Looking now to Fig 3B, an attacker signal strength curve 11 is shown, indicating signal strength when a resource use attack occurs. In this case, the attacker signal strength curve 11 remains high during the header reception, (time t0and ti).However, during the payload reception (time ti - 12), there is no signal being transmitted by the transmitter device 1.

[0042] Fig 4 is a flow chart illustrating methods for mitigating a resource use attack by a transmitter device 1 against a receiver device 2 over a wireless interface 4. The method is performed in a receiver device 2, such as the receiver device 2 of Fig 1.

[0043] The wireless interface 4 can e.g. comply with any communication standard in accordance with IEEE 802.15.4, such as Thread, ZigBee, Wireless Heart, Matter, etc. Alternatively or additionally, the wireless interface 4 can comply with Bluetooth, or BLE.

[0044] In a receive header step 40, the receiver device 2 receives a header transmission from a transmitter device 1. The header 21 forms part of a radio frame 20. The receiver device 2 decodes the header and interprets the content of the header 21. The header 21 comprises an indicator of size (e.g. in bytes) of a subsequent transmission of a payload 22 in the radio frame 20. The receiving includes performing a headermeasurement, being a measurement of received signal strength of the header transmission. The header measurement can be an RSSI measurement.

[0045] In a perform payload measurement step 42, the receiver device 2 performs a payload measurement, being a measurement of received signal strength measurement when the payload 22 of the radio frame 20 is expected to be received. The payload measurement can be an RSSI measurement. The expectation of when the payload is to be received can be based on the size indicated in the header, to make sure the measurement occurs after the header transmission is done, and before the payload has ended to be received.

[0046] In a conditional pay load measurement low step 44, the receiver device 2 evaluates the payload measurement. If the payload measurement is low, e.g. by determining that the payload measurement is lower than a threshold, this indicates a resource use attack (where an payload indicated in the header is not transmitted by the transmitter device 1). The method then proceeds to a release resources step 46. Otherwise, when the payload measurement is not low, the method proceeds to an optional measure more step 45, or, if the measure more step 45 is not performed, the method ends. The threshold can be determined in relation to the header measurement, e.g. x % of the header measurement. Alternatively, the threshold can be a static value, e.g. -y dBm.

[0047] In the optional conditional measure more step 45, the receiver device 2 determines whether more payload measurements are to be performed. For instance, payload measurements can be repeated for a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount, i.e. indicating that a resource use attack is in progress. The indicated transmission time is the time for transmission of the payload 22 of the size indicated in the header 21. If there are more (payload) measurements to make the method returns to the perform pay load measurement step 42 to perform a new measurement.

[0048] In a release resources step 46, the receiver device 2 releases resources used for receiving the payload. The release of resources can comprise ending attempts todecode the payload. Alternatively or additionally, the release of resources can comprise setting the receiver device 2 in a state where it is ready to receive a new header.

[0049] By releasing the resources when the low power payload is detected, the resource use attack is halted, and its effect is greatly reduced. The detection does not rely on any checksum calculation, which would require listening and decoding for the entire time that the indicated payload would be transmitted, which would thus not reduce the effect of the resource use attack. Hence, according to embodiments presented herein, during a resource use attack, energy waste is reduced in the receiver device 2 and resources and bandwidth are made available to receive legitimate frames in the time that the receiver device 2 otherwise would be busy to attempt receiving the indicated payload from the transmitter device 1 of the attacker.

[0050] Fig 5 is a schematic diagram illustrating components of the receiver device 2 of Fig 1. Processing circuitry 60 is provided using any combination of one or more of a suitable central processing unit (CPU), graphics processing unit (GPU), multiprocessor, neural processing unit (NPU), microcontroller, digital signal processor (DSP), etc., capable of executing software instructions 67 stored in memory circuitry 64, which can thus be a computer program product. The processing circuitry 60 could alternatively be implemented using an application specific integrated circuit (ASIC), field programmable gate array (FPGA), etc. The processing circuitry 60 can be configured to execute the method described with reference to Fig 4 above.

[0051] The memory circuitry 64 can be any combination of random-access memory (RAM) and / or read-only memory (ROM). The memory circuitry 64 also comprises non- transitory persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid-state memory or even remotely mounted memory.

[0052] A data memory 66 is also provided for reading and / or storing data during execution of software instructions in the processing circuitry 60. The data memory 66 can be any combination of RAM and / or ROM.

[0053] An I / O interface 62 is provided for communicating with external and / or internal entities. The I / O interface 62 supports short-range wireless communication, e.g. based on any communication protocol complying with Institute of Electrical and Electronics Engineers (IEEE) 802.15.4, such as Thread, ZigBee, Wireless Heart, Matter, etc. Alternatively or additionally, the I / O interface 62 comprise with Bluetooth, or Bluetooth low energy, BLE.

[0054] Other components of the receiver device 2 are omitted in order not to obscure the concepts presented herein.

[0055] Fig 6 shows one example of a computer program product 90 comprising computer readable means. On this computer readable means, a computer program 91 can be stored in a non-transitory memory. The computer program can cause processing circuitry to execute a method according to embodiments described herein. In this example, the computer program product 90 is in the form of a removable solid-state memory, e.g. a Universal Serial Bus (USB) drive. As explained above, the computer program product could also be embodied in a memory of a device, such as the computer program product 64 of Fig 5. While the computer program 91 is here schematically shown as a section of the removable solid-state memory, the computer program can be stored in any way which is suitable for the computer program product, such as another type of removable solid-state memory, or an optical disc, such as a CD (compact disc), a DVD (digital versatile disc) or a Blu-Ray disc.

[0056] Here now follows a set of embodiments from a slightly different perspective, enumerated with roman numerals.

[0057] I. A method for mitigating a resource use attack by a transmitter device against a receiver device over a wireless interface, the method being performed by a receiver device, the method comprising: receiving a header transmission from a transmitter device, the header forming part of a radio frame, the header comprising an indicator of size of a subsequent transmission of a payload in the radio frame, wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission;performing a payload measurement, being a measurement of received signal strength measurement when the payload of the radio frame is expected to be received; determining that the payload measurement is lower than a threshold; and releasing resources used for receiving the payload.

[0058] II. The method according to embodiment I, wherein the performing payload measurement is repeated for a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount.

[0059] III. The method according to embodiment I or embodiment II, wherein the releasing resources comprises ending attempts to decode the payload.

[0060] IV. The method according to any one of the preceding embodiments, wherein the releasing resources comprises setting the receiver device in a state where it is ready to receive a new header.

[0061] V. The method according to any one of the preceding embodiments, wherein the wireless interface is a short-range wireless interface.

[0062] VI. The method according to embodiment V, wherein the wireless interface complies with any communication standard in accordance with Institute of Electrical and Electronics Engineers, IEEE, 802.15.4.

[0063] VII. The method according to embodiment V, wherein the wireless interface complies with Bluetooth, Bluetooth low energy, BLE or Z-Wave.

[0064] VIII. The method according to any one of the preceding embodiments, wherein the threshold is determined in relation to the header measurement.

[0065] IX. The method according to any one of embodiments I to VIII, wherein the threshold is a static value.

[0066] X. A receiver device for mitigating a resource use attack by a transmitter device against the receiver device over a wireless interface, the receiver device comprising:processing circuitry; and memory circuitry storing instructions that, when executed by the processing circuitry, cause the receiver device to: receive a header transmission from a transmitter device, the header forming part of a radio frame, the header comprising an indicator of size of a subsequent transmission of a payload in the radio frame, wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; perform a payload measurement, being a measurement of received signal strength measurement when the payload of the radio frame is expected to be received; determine that the payload measurement is lower than a threshold; and release resources used for receiving the payload.

[0067] XI. The receiver device according to embodiment X, further comprising instructions that, when executed by the processing circuitry, cause the receiver device to repeat the payload measurement a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount.

[0068] XII. The receiver device according to embodiment X or embodiment XI, wherein the instructions to release resources comprise instructions that, when executed by the processing circuitry, cause the receiver device to end attempts to decode the payload.

[0069] XIII. The receiver device according to any one of embodiments X to XII, wherein the instructions to release resources comprises instructions that, when executed by the processing circuitry, cause the receiver device to set the receiver device in a state where it is ready to receive a new header.

[0070] XIV. The receiver device according to any one of embodiments X to XIII, wherein the wireless interface is a short-range wireless interface.

[0071] XV. The receiver device according to embodiment XIV, wherein the wireless interface complies with any communication standard in accordance with Institute of Electrical and Electronics Engineers, IEEE, 802.15.4.

[0072] XVI. The receiver device according to embodiment XIV, wherein the wireless interface complies with Bluetooth, or Bluetooth low energy, BLE.

[0073] XVII. The receiver device according to any one of embodiments X to XVI, wherein the threshold is determined in relation to the header measurement.

[0074] XVIII. The receiver device according to any one of embodiments X to XVII, wherein the threshold is a static value.

[0075] XIX. A computer program for mitigating a resource use attack by a transmitter device against a receiver device over a wireless interface, the computer program comprising computer program code which, when executed on a receiver device causes the receiver device to: receive a header transmission from a transmitter device, the header forming part of a radio frame, the header comprising an indicator of size of a subsequent transmission of a payload in the radio frame, wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; perform a payload measurement, being a measurement of received signal strength measurement when the payload of the radio frame is expected to be received; determine that the payload measurement is lower than a threshold; and release resources used for receiving the payload.

[0076] XX. A computer program product comprising a computer program according to embodiment XIX and a computer readable means comprising non- transitory memory in which the computer program is stored.

[0077] The aspects of the present disclosure have mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. Thus, whilevarious aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims.

Claims

CLAIMS1. A method for mitigating a resource use attack by a transmitter device (i) against a receiver device (2) over a wireless interface (4), the method being performed by a receiver device (2), the method comprising: receiving (40) a header transmission from a transmitter device (1), the header (21) forming part of a radio frame (20), the header (21) comprising an indicator of size of a subsequent transmission of a payload (22) in the radio frame (20), wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; performing (42) a payload measurement, being a measurement of received signal strength measurement when the payload (22) of the radio frame (20) is expected to be received, wherein the expectation of when the payload is to be received is based on the size indicated in the header; determining (44) that the payload measurement is lower than a threshold; and releasing (46) resources used for receiving the payload.

2. The method according to claim 1, wherein the performing (42) payload measurement is repeated for a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount.

3. The method according to claim 1 or 2, wherein the releasing (46) resources comprises ending attempts to decode the payload.

4. The method according to any one of the preceding claims, wherein the releasing (46) resources comprises setting the receiver device (2) in a state where it is ready to receive a new header.

5. The method according to any one of the preceding claims, wherein the wireless interface is a short-range wireless interface.

6. The method according to claim 5, wherein the wireless interface (4) complies with any communication standard in accordance with Institute of Electrical and Electronics Engineers, IEEE, 802.15.4.

7. The method according to claim 5, wherein the wireless interface (4) complies with Bluetooth, Bluetooth low energy, BLE or Z-Wave.

8. The method according to any one of the preceding claims, wherein the threshold is determined in relation to the header measurement.

9. The method according to any one of claims 1 to 8, wherein the threshold is a static value.

10. A receiver device (2) for mitigating a resource use attack by a transmitter device (1) against the receiver device (2) over a wireless interface (4), the receiver device (2) comprising: processing circuitry (60); and memory circuitry (64) storing instructions (67) that, when executed by the processing circuitry, cause the receiver device (2) to: receive a header transmission from a transmitter device (1), the header (21) forming part of a radio frame (20), the header (21) comprising an indicator of size of a subsequent transmission of a payload (22) in the radio frame (20), wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; perform a payload measurement, being a measurement of received signal strength measurement when the payload (22) of the radio frame (20) is expected to be received, wherein the expectation of when the payload is to be received is based on the size indicated in the header; determine that the payload measurement is lower than a threshold; and release resources used for receiving the payload.

11. The receiver device (2) according to claim 10, further comprising instructions (67) that, when executed by the processing circuitry, cause the content receiver device (2) to repeat the payload measurement a plurality of times during an indicated transmission time until the payload measurement is lower than the header measurement by more than a threshold amount.

12. The receiver device (2) according to claim 10 or 11, wherein the instructions to release resources comprise instructions (67) that, when executed by the processing circuitry, cause the content receiver device (2) to end attempts to decode the payload.13- The receiver device (2) according to any one of claims 10 to 12, wherein the instructions to release resources comprises instructions (67) that, when executed by the processing circuitry, cause the content receiver device (2) to set the receiver device (2) in a state where it is ready to receive a new header.

14. The receiver device (2) according to any one of claims 10 to 13, wherein the wireless interface is a short-range wireless interface.

15. The receiver device (2) according to claim 14, wherein the wireless interface (4) complies with any communication standard in accordance with Institute of Electrical and Electronics Engineers, IEEE, 802.15.4.

16. The receiver device (2) according to claim 14, wherein the wireless interface (4) complies with Bluetooth, or Bluetooth low energy, BLE.

17. The receiver device (2) according to any one of claims 10 to 16, wherein the threshold is determined in relation to the header measurement.

18. The receiver device (2) according to any one of claims 10 to 17, wherein the threshold is a static value.

19. A computer program (67, 91) for mitigating a resource use attack by a transmitter device (1) against a receiver device (2) over a wireless interface (4), the computer program comprising computer program code which, when executed on a receiver device (2) causes the receiver device (2) to: receive a header transmission from a transmitter device (1), the header (21) forming part of a radio frame (20), the header (21) comprising an indicator of size of a subsequent transmission of a payload (22) in the radio frame (20), wherein the receiving includes performing a header measurement, being a measurement of received signal strength of the header transmission; perform a payload measurement, being a measurement of received signal strength measurement when the payload (22) of the radio frame (20) is expected to be received, wherein the expectation of when the payload is to be received is based on the size indicated in the header; determine that the payload measurement is lower than a threshold; and release resources used for receiving the payload.

20. A computer program product (64, 90) comprising a computer program according to claim 19 and a computer readable means comprising non-transitory memory in which the computer program is stored.

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