水槽 摩恩 不好:小心！你身边的智能间谍！Smart Phones Could Hear You...

2011年10月18日，星期二

    BY ROBERT LEMOS 

作者：ROBERT LEMOS

The sensors inside modern smart phones present a range of security threats. An attacker who compromises a phone can, for example, track the owner's location by GPS, use the camera to see the phone's surroundings, or turn on its microphone to record conversations.

今天的智能手机内置多种传感器，而你有没有想过，这些传感器却可能会给你带来安全的威胁？一旦有人侵入了你的手机，他就有可能通过GPS定位你的位置，通过摄像头探查你周边的环境，或者打开麦克风来偷听你们的谈话。

At a conference in Chicago on Thursday, a group of computer researchers from Georgia Tech will report on another potential threat. The researchers have shown that the accelerometer and orientation sensor of a phone resting on a surface can be used to eavesdrop as a password is entered using a keyboard on the same surface. They were able to capture the words typed on the keyboard with as much as 80 percent accuracy.

智能手机的威胁其实不仅仅是这些，在本周二将于芝加哥举行的一次会议上，来自佐治亚理工的几位电脑研究人员会就另一种潜在的威胁发表报告。他们发现，当你把手机放在某个表面的时候（譬如桌面），如果你在同一个表面用普通键盘进行密码输入的话，那么这部手机中的重力感应器和陀螺仪就可以用于盗窃你的密码，准确率高达80%。

"There is information that is being leaked, and of the hardware on your phone, the accelerometer is the one thing that no one ever worried about," says Patrick Traynor, assistant professor in the school of computer science at Georgia Tech and a member of the research team. "No one thought that you could turn on the accelerometer and get any meaningful data."

“人们的信息正在被自己的手机所泄露，但是对于手机里面的这些玩意儿来说，重力感应器以前是没有人担心过的，”研究组成员，佐治亚理工计算机科学系助理教授Patrick Traynor如是说：“从没有人以为通过重力感应器能得到什么有意义的信息。”

The accelerometer in the phone the researchers used samples only 100 times a second, so they did not have enough data to determine the exact keys struck. Instead, the researchers used the data from the accelerometer to determine whether key taps were on the right or left side of the keyboard and to gauge the delays between keystrokes. Using this information, they were able to figure out a list of potential keystroke pairs. The results were then compared with a 58,000-entry dictionary. They will present the work at the ACM Conference on Computer and Communications Security.

而研究人员所使用的手机，其内置重力感应器采样率仅为100次每秒，因此他们并没有足够的数据来计算得到明确的密码。相反，研究者们利用从重力感应器得到的数据，来判断相应的按键到底是在键盘的左边还是键盘的右边，并计量两个按键之间的延时。利用这样的信息，他们就可以得出一系列有可能的键位配对，然后再把这些结果与一份拥有58000份条目的词典进行比对，最终得到可能的密码。这个研究的相关成果将会发表在本次ACM计算机与通信安全会议上。

These graphs show measurements recorded by a smart phone as letters are typed on a nearby keyboard. The device can distinguish between "a" at the left of the keyboard and "l" on the right, as well as between two pairs: "pq" and "nm." (Georgia Tech) 

这些图片显示了智能手机记录下来的按键信息，你可以发现，它能够判断a和I的区别，也可以判断nm和pq的区别。（佐治亚理工）

A real-world attack would, of course, require a victim to habitually place a phone and keyboard on the same work surface. Vibrations inherent in the environment could also complicate matters. A tall building adds noise because it sways, and offices near a major road will be affected by traffic vibrations. The composition of the surface makes a big difference as well, says Traynor. Pine desktops conduct vibrations extremely well, as do glass ones, making them ideal surfaces for the attack. But a tiled kitchen counter is basically inscrutable.

不过当然，在实际生活中，如果你想要通过这种方式来获取别人的密码的话，你还需要很多的条件：首先，你的目标需要把手机和键盘放在同一个桌面上。其次，振动干扰也会成为你的一个大麻烦：如果你的目标是在一栋高楼里，由于高楼总是会轻微的晃动，这就会产生干扰；而如果他是在路边的办公室里，那路上的交通也会产生振动干扰。另外，据Traynor所说，桌面材料不同，结果也会大不同：松木桌面和玻璃桌面非常容易传导振动，是最理想的材料，而如果遇上了瓷砖橱柜，那你就基本没辙了。

To make the attack succeed, the dictionary would need to be tailored to the specific target. "The best-case scenario here, if you are an attacker, is to go after a very specific person," says Traynor. "I think the attack is realistic in that case."

另外，如果你真想这么干的话，那你用来比对的词典必须是针对你的目标来设计的，量体裁衣，有的放矢。“最好的情形是，你能够根据特定的目标来进行你的工作，”Traynor说：“我想这样的情况才更加的现实。”

As phone technology improves, attacks via the accelerometer could become more feasible. The researchers' initial experiments used Apple's iPhone 3GS, but the phone's accelerometer lacked the necessary sensitivity. The researchers then moved to the iPhone 4, which uses a gyroscope to remove noise from the accelerometer data, and had much greater success.

随着手机技术的发展，通过重力感应器能实现的攻击方式会变得更加的灵活。最初，研究者们的实验使用的是苹果的iPhone 3GS，但是3GS的重力感应器却不够灵敏。于是后来，实验的对象就换成了iPhone 4。iPhone 4内置陀螺仪，用以对重力感应器采集的信号进行滤波，实验效果才得以改善。

While the attack technique is interesting, it's unlikely to become a real threat for some time, says Charlie Miller, principal security consultant with Accuvant, a compliance and security research firm. "It's cool because it is very James Bond-ish," he says. "But it might easier to turn on the mike and listen to the target talk on the phone."

虽然这项技术非常的有趣，但是在一段时期内它不太可能成为一个现实的威胁。Charlie Miller如是说，他供职于一家法规及安全性研究公司Accuvant，担任首席安全顾问。“这项技术很酷，很007，”他说：“但也许直接使用麦克风去监听目标的电话会要容易的多。”