What behavior is likely to indicate the presence of a rootkit on a system?

Unusual network traffic can be a significant indicator of a rootkit's presence on a system. Rootkits are designed to gain unauthorized access to a computer while concealing their existence and the presence of other malicious software. One common behavior of rootkits is that they facilitate external communication, allowing attackers to control the infected system remotely. This often manifests as unexpected spikes in network traffic, unusual outbound connections to unfamiliar IP addresses, or frequent communication with known command-and-control servers.

In essence, the abnormal nature of the network traffic suggests that something malicious may be at work, often correlating with the stealthy operations of rootkits. Regular software updates, standard login attempts, and a reduction in system speed can all occur in various scenarios that do not necessarily indicate a security breach; therefore, they are not as definitive as unusual network traffic in identifying the presence of a rootkit.