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80 lines
2.4 KiB
Markdown
80 lines
2.4 KiB
Markdown
<!--
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Author: Xianjun jiao
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SPDX-FileCopyrightText: 2021 UGent
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SPDX-License-Identifier: AGPL-3.0-or-later
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-->
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[ACM WiSec 2021. Openwifi CSI fuzzer for authorized sensing and covert channels](https://dl.acm.org/doi/pdf/10.1145/3448300.3468255)
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CSI (Channel State Information) of WiFi systems is available in some WiFi chips and can be used for sensing the environment (keystrokes, people, object) passively and secretly.
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## Concept
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How could a CSI fuzzer stop unauthorized sensing?
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![](./csi-fuzzer-system-before-vs-now.png)
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CSI fuzzer implementation principle.
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![](./csi-fuzzer-principle.png)
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## Demo instructions
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Thanks to the full-duplex capability and CSI extraction feature of openwifi, you can monitor the artificial channel response via [side channel](./csi.md) by Tx-Rx over the air coupling without affecting the normal operation/traffic of openwifi. Before the self-monitoring, the auto-mute during Tx needs to be disabled.
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The full demo steps are:
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```
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ssh root@192.168.10.122
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(password: openwifi)
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cd openwifi
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./fosdem-11ag.sh
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(setup openwifi AP)
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./sdrctl dev sdr0 set reg xpu 1 1
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(Disable auto-muting to listen self-TX)
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insmod side_ch.ko num_eq_init=0
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./side_ch_ctl wh1h2001
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./side_ch_ctl wh6hffffffff
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(Let's only monitor self-beacon-TX CSI over-the-air loopback)
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./side_ch_ctl g1
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```
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Go to openwifi/user_space/side_ch_ctl_src, and run `python3 side_info_display.py 0`. You should see the over-the-air loopback CSI when CSI fuzzer is not enabled. Then stop the python3 side_info_display.py script to ease the next step.
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Start another ssh session to the openwifi board:
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```
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ssh root@192.168.10.122
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(password: openwifi)
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cd openwifi
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./csi_fuzzer_scan.sh 1
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(CSI fuzzer applies possible artificial CSI by scanning all values)
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(csi_fuzzer.sh is called. Please read both scripts to understand these commands)
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```
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Go to openwifi/user_space/side_ch_ctl_src, and run `python3 side_info_display.py 0`. Now you should see that CSI keeps changing like in this [video](https://youtu.be/aOPYwT77Qdw).
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# Further explanation on parameters
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CSI fuzzer in openwifi system architecture and related commands.
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![](./csi-fuzzer-implementation.png)
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# Example fuzzed CSI
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CSI self-monitoring before fuzzing.
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![](./csi-fuzzer-beacon-ant-back-0.jpg)
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CSI self-monitoring after fuzzing command: `csi_fuzzer.sh 1 45 0 13`
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![](./csi-fuzzer-beacon-ant-back-1-45-0-13.jpg)
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`csi_fuzzer_scan.sh` can scan the c1 and c2 in different styles/modes by calling `csi_fuzzer.sh`.
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