Biblio

The Time and the Time Synchronization are veryimportant especially for the computer networks performing timesensitive operations. It is very important for all the datacenters, markets, finance companies, industrial networks, commercial applications, e-mail and communication-related Clients and servers, active directory services, authentication mechanisms, and wired and wireless communication. For instance. a sensitive time system is crucial for financial networks processing a large amount of data on a daily basis. If the computer does not communicate with other Computers Or Other systems using time, then the time information might not be important. The NTP acts as a Single time source in order to synchronize all the devices in a network. While the computer networks communicate with each other between different time zones and different locations on the earth; the main time doesn't need to be the same all around the world but it must be very sensitive otherwise the networks at different locations might work on different times.As the main time sources, most of networks uses the Coordinated Universal Time The is important also for security. The hackers and the malware such as computer Viruses use the time inconsistencies in order to overcome all the security measures such as firewalls or antivirus software; without a correct time, any system might be taken under control. If all the devices are connected to STP time. then it would be more difficult for malicious to the System.

In this paper, we scrutinize a way through which covert messages are sent and received using the Network Time Protocol (NTP), which is not easily detected since NTP should be present in most environment to synchronize the clock between clients and servers using at least one time server. We also present a proof of concept and investigate the throughput and robustness of this covert channel. This channel will use the 32 bits of fraction of seconds in timestamp to send the covert message. It also uses "Peer Clock Precision" field to track the messages between sender and receiver.

With its high penetration rate and relatively good clock accuracy, smartphones are replacing watches in several market segments. Modern smartphones have more than one clock source to complement each other: NITZ (Network Identity and Time Zone), NTP (Network Time Protocol), and GNSS (Global Navigation Satellite System) including GPS. NITZ information is delivered by the cellular core network, indicating the network name and clock information. NTP provides a facility to synchronize the clock with a time server. Among these clock sources, only NITZ and NTP are updated without user interaction, as location services require manual activation. In this paper, we analyze security aspects of these clock sources and their impact on security features of modern smartphones. In particular, we investigate NITZ and NTP procedures over cellular networks (2G, 3G and 4G) and Wi-Fi communication respectively. Furthermore, we analyze several European, Asian, and American cellular networks from NITZ perspective. We identify three classes of vulnerabilities: specification issues in a cellular protocol, configurational issues in cellular network deployments, and implementation issues in different mobile OS's. We demonstrate how an attacker with low cost setup can spoof NITZ and NTP messages to cause Denial of Service attacks. Finally, we propose methods for securely synchronizing the clock on smartphones.