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Device Trails

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Wi-Fi Networks

Similar to Bluetooth data are wireless network settings. The profiles of all Wi-Fi networks that a computer can access are kept in the host. So, whenever users connect to a new Wi-Fi network and enter the security details needed to access it, information is kept until explicitly deleted. This is done so that when users return to known networks, the computer can connect without repeatedly asking security questions.

Anyone with access to the computer can easily read which profiles are present. In fact, in many Wi-Fi implementations (Windows WZC included), the computer tries to search the available networks whenever it is disconnected from one. This search reveals which profiles and what SSID the computer is searching for. Such information can give attackers significant advantages. If an unsecured network (such as in an Internet cafe or hotel access point) is approved by a user even once, the computer probes for that network wherever it is. Attackers can simulate the SSID of the particular network, and get a LAN connection with the victim machine.

Security Tools

The information we've discussed to this point is of primary interest to security officers who want to enforce the organization's policy. They want to check whether employees used storage devices (MP3 players, for example) that are not permitted by organizational policy. Furthermore, if a data leakage is suspected, they can audit specific computers to detect whether dangerous storage devices have been previously connected.

One such assessment tool dealing with this kind of forensics information is Safend Auditor, a tool our company developed ( With this tool, system administrators can learn about all devices historically connected to computers in their organization. Furthermore, Auditor marks the devices that are currently connected when the scan is administered (Figure 1), letting system administrators catch someone violating organizational policy in real time.

Figure 1: Auditor report.

In addition to knowing if the employees follow security policy, auditing tools can be used as a risk assessment tool, too. Auditor generates an audit report that can be used to illustrate how many unique devices of each kind were introduced in the organization. If a device is lost, an audit report assists in tracking the device's current location by providing a connection history. Quite possibly, the "lost" device will turn up connected to another computer within the network.

To be productive, such a tool requires administrative privileges for the system being scanned. The optional scanning mechanisms—WMI, Remote Registry, Setup API—all require some networking services in the scanned operating system to run. A personal firewall on the scanned computer may interrupt such an audit. If the computer is not responding in any port, no information can be gathered from it.

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