可以用 SDR&HackRF 监测电脑噪音吗？

[sdijeenx]

当电脑接地不良时读写硬盘会从耳机中发出声音不大但是很吵的数据传输噪音（当然还有其他方式让电脑发出这种噪音）。昨晚逛淘宝的时候突然想到了这个问题于是想买个 SDR （ TV 棒）或者 HackRF 监测噪音。

于是想问下有没有大佬做过类似的事？噪音中心频率大概是多少，频率会不会超过 1.7GHz ？

[inframe]

耳机线的电磁屏蔽没做好
电源也可能有问题
sdr 要测试可以直接连耳机线都 sdr 上

[jianguocheng]

咦，rf 不是检测无线电的吗，声波是不是不行吧

[reechangs]

一个是机械波，一个是电磁波...

[sdijeenx]

@jianguocheng 应该是电磁波，我用的固态硬盘=3=

[sdijeenx]

刚发现电视机顶盒也有超声波频噪音好神奇。
先买个 rtl2832 看看附近的有没有电磁辐射啥的，不行的话再上 HackRF=3=

[dream7758522]

监控到噪音有啥用途？

[GPLer]

@dream7758522 如果我没有记错的话可以直接截获数据。←_←

[sdijeenx]

@dream7758522 找出噪音产生原因并消除它。
想象一下你身边有个一直播放白噪音的收音机但是你关不掉他的感觉。

[GPLer]

[DiskFiltration: Data Exfiltration from Speakerless Air-Gapped Computers via Covert Hard Drive Noise]( https://arxiv.org/abs/1608.03431)

Mordechai Guri, Yosef Solewicz, Andrey Daidakulov, Yuval Elovici
(Submitted on 11 Aug 2016)

Air-gapped computers are disconnected from the Internet physically and logically. This measure is taken in order to prevent the leakage of sensitive data from secured networks. In the past, it has been shown that malware can exfiltrate data from air-gapped computers by transmitting ultrasonic signals via the computer's speakers. However, such acoustic communication relies on the availability of speakers on a computer. In this paper, we present 'DiskFiltration,' a covert channel which facilitates the leakage of data from an air-gapped compute via acoustic signals emitted from its hard disk drive (HDD). Our method is unique in that, unlike other acoustic covert channels, it doesn't require the presence of speakers or audio hardware in the air-gapped computer. A malware installed on a compromised machine can generate acoustic emissions at specific audio frequencies by controlling the movements of the HDD's actuator arm. Digital Information can be modulated over the acoustic signals and then be picked up by a nearby receiver (e.g., smartphone, smartwatch, laptop, etc.). We examine the HDD anatomy and analyze its acoustical characteristics. We also present signal generation and detection, and data modulation and demodulation algorithms. Based on our proposed method, we developed a transmitter on a personal computer and a receiver on a smartphone, and we provide the design and implementation details. We also evaluate our covert channel on various types of internal and external HDDs in different computer chassis and at various distances. With DiskFiltration we were able to covertly transmit data (e.g., passwords, encryption keys, and keylogging data) between air-gapped computers to a smartphone at an effective bit rate of 180 bits/minute (10,800 bits/hour) and a distance of up to two meters (six feet).

[GPLer]

@sdijeenx 也许可以参考下 https://www.zhihu.com/question/21412180 这个？

[sdijeenx]

@GPLer 知乎那个解释了开关电源产生噪音的原因，不过还不清楚是否跟硬盘产生噪音的原因一致（我电脑用的是 SSD+HDD，之前发现当噪音产生时 HDD 的磁臂没有工作。）

[sdijeenx]

@GPLer 论文里 HDD 的 E 和 B 部分使用 PWM 控制，C 部分使用模拟信号读写数据。这些都可能是噪音来源=3=

[Cu635]

你这样监测到的是电脑产生的释放到空间中的杂散电磁干扰——很明显，“电脑产生的”、“释放到空间中的”这就已经限定原始范围了，lz 发帖的时候恐怕是没有想到第二个限制吧？
而且你监测到的结果也是合并了其它来源已经存在的空间电磁波之后的结果，干扰也是很大的……

[sdijeenx]

@Cu635 我买的 TV 棒过几天就到了，到时看看能检测到什么信号。

[sdijeenx]

@Cu635
试了一下效果不错～
用 SDR 能检测到某设备通信时会发出频率是 23561.300KHz 的电磁干扰╮(╯▽╰)╭