Awesome

Presentation Clickers

I was in the mood for some RF reverse-engineering, so I ordered a few presentation clickers and had a bit of fun.

This is a fork of nrf-research-firmware (which I wrote a few years ago at Bastille). I've added support for a few new transceivers/protocols, and included keystroke injection POCs for 13 common presentation clickers.

History

• 2019-04-20 - released first batch (8 devices)
• 2019-04-21 - released second batch (5 devices)

Devices Vulnerable to Keystroke Injection

Protocols

Logitech Encrypted

Overview

This is the standard encrypted Logitech keyboard protocol, as used by the R500. It's sort-of vulnerable to the "encrypted keystroke injection" attack I documented with Logitech Unifying keyboards as part of the MouseJack project.

I say sort-of, because not all HID scan codes are accepted. Specifically, 0x04-0x1D (A-Z) are replaced by 0x00 when the dongle sends the packet to the host computer, which means we can inject whatever we want, as long as it isn't a letter. The other exception is that ctrl key-chords are allowed, even when they include letters.

Effective keystroke injection via the R500 requires that we get a little creative.

Let's assume the target is in a bash session. In bash, we can encode our characters in base-8, encoding commands containing letters that we want our target to execute.

For instance, ping google.com is encoded as $'\160\151\156\147' $'\147\157\157\147\154\145\056\143\157\155'. If we send this string to a bash session and then send enter, the command ping google.com will be invoked on the target machine.

Device Discovery

You can find the address of your Logitech R500 using nrf24-scanner as follows:

sudo ./tools/nrf24-scanner.py -c {2..74..3} -l

Packets should look something like this:

[2019-04-21 13:11:52.507]  62   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 13:11:52.515]  62   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 13:11:52.523]  62  22  85:D1:9D:FE:07  00:D3:4D:6F:B6:1B:E6:05:A2:B4:8B:98:F9:C2:00:00:00:00:00:00:00:81

Injection

Injection is possible because the dongle doesn't enforce incementing AES counters, so you can replay packets. A packet sent OTA is made up of a USB HID payload which has been encrypted in AES counter mode, and then the counter. When you press a button on the presentation clicker, it generates a key down packet, and a key up packet. The key up packet is all 0's, which gives us nice and clean key material that we can reuse, XOR with our own payload, and send OTA.

It shouldn't be hard to automate the process of listening for a button press, pulling out the second (key up) packet, and automatically using it for the key-material reference. But I'm lazy, so you'll first need to watch a button press yourself, which looks like this:

[2019-04-21 16:02:56.451]  65   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 16:02:56.459]  65   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 16:02:56.468]  65  22  85:D1:9D:FE:07  00:D3:E6:7B:35:8C:BB:2C:7D:5B:8B:98:FA:76:00:00:00:00:00:00:00:B9
[2019-04-21 16:02:56.475]  65   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 16:02:56.507]  65   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 16:02:56.516]  65  22  85:D1:9D:FE:07  00:D3:99:D6:D3:8D:49:25:F5:4D:8B:98:FA:77:00:00:00:00:00:00:00:1A
[2019-04-21 16:02:56.524]  65   5  85:D1:9D:FE:07  00:40:00:08:B8
[2019-04-21 16:02:56.532]  65   5  85:D1:9D:FE:07  00:40:00:08:B8

The second 22-byte packet is the key-up packet.

Remove the last byte of the payload, and copy and paste the string into logitech.py, replacing KEYUP_REF.

(It shouldn't work without updating KEYUP_REF, but if it does, please let me know!)

Injection

Inject the bash ping google.com base-8-encoded keystroke sequence into a specific Logitech R500 dongle (address 85:D1:9D:FE:07):

sudo ./tools/r500-injector.py -l -a 85:D1:9D:FE:07

Logitech Unencrypted

Overview

This is the standard unencrypted Logitech protocol, used by the R400/R800.

Device Discovery

You can find the address of your Logitech R400/R800 using nrf24-scanner as follows:

sudo ./tools/nrf24-scanner.py -c {2..74..3} -l

Packets should look something like this:

[2019-04-21 12:58:43.466]  32   0  9D:9E:95:52:07  
[2019-04-21 12:58:43.620]  32  10  9D:9E:95:52:07  00:C1:00:00:00:00:00:00:00:3F

Injection

Inject the test keystroke sequence into a specific Logitech R400/R800 dongle (address 9D:9E:95:52:07):

sudo ./tools/preso-injector.py -l -f logitech -a 9D:9E:95:52:07

Rii Wireless Presenter

Overview

The Rii Wireless Presenter (rounded-pen) is based on the BK2451 (which seems to be a nRF24 clone). This looks like a generic protocol, based on the prevalence of sister devices, so I'll probably recategorize this after getting some more data.

It is functionally an unencrypted wireless keyboard, vulnerable to keystroke injection.

PHY

The Wireless Presenter (rounded-pen) uses 250Kb/s nRF24 Enhanced Shockburst (w/o ACKs it seems), and a 5-byte address. The device I tested was observed to be camping at 2425 MHz, but it seems to use some sort of frequency-agility scheme. In practice, it is necessary to send some dummy packets on the target channel before sending keystroke packets.

I suspect there is some channel hopping going on, which I haven't characterized, but targeting a single channel is sufficient to demonstrate keystroke injection.

Device Discovery

You can find the address of your Wireless Presenter (rounded-pen) using nrf24-scanner as follows:

sudo ./tools/nrf24-scanner.py -c 25 -l -R 250K -A 5

Note that yours might be on another channel.

Packets should look something like this:

[2019-04-21 11:50:33.116]  25   3  6D:8C:01:14:25  4B:51:00
[2019-04-21 11:50:33.212]  25   3  6D:8C:01:14:25  4C:00:00
[2019-04-21 11:50:33.522]  25   3  6D:8C:01:14:25  4D:51:00
[2019-04-21 11:50:33.565]  25   3  6D:8C:01:14:25  4E:00:00

Injection

Inject the test keystroke sequence into a specific Rii dongle (address 6D:8C:01:14:25):

sudo ./tools/preso-injector.py -l -f rii -a 6D:8C:01:14:25

TBBSC DSIT-60

Overview

The TBBSC DSIT-60 is based on the BK2451 (which seems to be a nRF24 clone). There are apparent sister devices (i.e. this one) which I haven't tested. For the moment I am categorizing this as a distinct protocol, but that will likely change once I test the sister device(s).

It is functionally an unencrypted wireless keyboard, vulnerable to keystroke injection.

PHY

The DSIT-60 uses 250Kb/s nRF24 Enhanced Shockburst (or at least an OTA equivalent) with a 3-byte address. The device I tested was observed to be camping at 2406 MHz, but I'm not sure what other channels it might use.

Device Discovery

You can find the address of your DSIT-60 using nrf24-scanner as follows:

sudo ./tools/nrf24-scanner.py -c 6 -l -R 250K -A 3

Note that yours might be on another channel, or there might be some frequency agility retuning that I haven't observed.

Packets should look something like this:

[2019-04-21 10:33:44.264]   6   4  87:02:09  0B:42:00:2B
[2019-04-21 10:33:44.269]   6   4  87:02:09  0B:42:00:2B
[2019-04-21 10:33:52.477]   6   4  87:02:09  01:42:00:28

Injection

Inject the test keystroke sequence into a specific TBBSC DSIT-60 dongle (address 87:02:09):

sudo ./tools/preso-injector.py -l -f tbbsc -a 87:02:09

AmazonBasics P-001

Overview

This is almost certainly a generic protocol, but I haven't looked at any of the sister devices yet (i.e. this one). For the moment I am categorizing this as a distinct protocol, but that will likely change once I test the sister device(s).

The P-001 is based on the nRF24 RFIC family, and is functionally an unencrypted wireless keyboard, vulnerable to keystroke injection.

PHY

The P-001 uses 2Mb/s nRF24 Enhanced Shockburst with 5-byte addresses, and channels 2402-2476.

Device Discovery

You can find the address of your P-001 using nrf24-scanner.py.

Pressing the right arrow should generate packets looking something like this:

[2019-04-20 12:59:13.908]  27   9  44:CB:66:A3:BE  00:00:00:00:00:00:00:00:01
[2019-04-20 12:59:13.909]  27   9  44:CB:66:A3:BE  00:00:00:00:00:00:00:00:01
[2019-04-20 12:59:13.999]  27   9  44:CB:66:A3:BE  00:00:4E:00:00:00:00:00:01
[2019-04-20 12:59:14.120]  27   9  44:CB:66:A3:BE  00:00:00:00:00:00:00:00:01
[2019-04-20 12:59:14.121]  27   9  44:CB:66:A3:BE  00:00:00:00:00:00:00:00:01
[2019-04-20 12:59:14.211]  27   9  44:CB:66:A3:BE  00:00:4E:00:00:00:00:00:01

Injection

Inject the test keystroke sequence into a specific AmazonBasics P-001 dongle (address 44:CB:66:A3:BE):

sudo ./tools/preso-injector.py -l -f amazon -a 44:CB:66:A3:BE

Canon PR100-R

Overview

I'm not sure if this protocol is unique to the Canon PR100-R, but since it's the only device I've observed that speaks the protocol, I'm leaving it in its own bucket until the data suggests otherwise.

The PR100-R is based on the PL1167 RFIC, and an unknown MCU.

The PR100-R is functionally an unencrypted wireless keyboard, vulnerable to keystroke injection.

PHY

The PR100-R uses a 1Mb/s FSK protocol operating on 5Mhz-spaced channels between 2406 Mhz and 2481 MHz.

Packets are whitened, and protected by a 16-bit CRC.

There don't appear to be ACKs sent back from the dongle, with the caveat that I've only reversed this protocol sufficient to demonstrate keystroke injection.

The protocol appears to take a frequency-agility approach to channel selection, and the dongle settles on a channel after the remote has transmitted on it for some number of packets. In practice, it is sufficient to transmit a few seconds of dummy packets before transmitting the keystroke packets.

Addressing

Based on the packet format, it's unclear if this protocol uses a fixed sync word, or a per-device address. I only looked at a single unit (due to the high price-point), so I wasn't able to fully vet the packet format.

The injection script works against my PR100-R, but may need to be modified for general use. If you have another PR100-R and are able to validate this, please let me know!

Injection

Inject the test keystroke sequence into a nearby Canon PR100-R dongle:

sudo ./tools/preso-injector.py -l -f canon

HS304

Overview

HS304 appears to be an application-specific RFIC for presentation clickers (or maybe wireless keyboards/mice). The name comes from the USB device string HAS HS304, and was the same for all devices in this set.

The RFIC was observed to be an unmarked SOP-16 package, with no apparent differences between vendors.

HS304-based devices are functionally unencrypted wireless keyboards, vulnerable to keystroke injection.

PHY

HS304 is a 1Mb/s FSK protocol operating on three channels in the 2.4GHz ISM band (2407, 2433, 2463). There don't appear to be ACKs sent from the dongle back to the presentation clicker, and packet delivery is ensured by transmitting each packet on each of the three channels.

In practice, reliable packet delivery can also be achieved by transmitting each packet multiple times on a single channel.

Packets are whitened, and protected by a 16-bit CRC.

Addressing

There is no addressing or pairing scheme, so keystroke injection does not require device-discovery, however the lack of ACKs precludes active discovery of dongles.

Injection

Inject the test keystroke sequence into nearby HS304 dongles:

sudo ./tools/preso-injector.py -l -f hs304

Sniffing

Receive and decode packets sent from nearby NS304 presentation clickers:

sudo ./tools/preso-scanner.py -l -f hs304