What characterizes a brute force attack?

A brute force attack is characterized by the methodical and exhaustive process of attempting every possible combination of characters to guess a password or encryption key. This technique relies on computing power to automate the guessing process, gradually testing out all possibilities until the correct one is found.

The strength of this approach is that it doesn't depend on any tricks or shortcuts; it's purely about the number of combinations being tried, which makes it a straightforward yet time-consuming attack method. While it can be very effective against weak passwords, it can be mitigated through the use of longer, more complex passwords and mechanisms like account lockout policies after failed attempts.

In contrast, the other options reflect different types of security threats. For instance, guessing passwords using common phrases points more towards a dictionary attack, which is a specific type of brute force attack but not the definition itself. Social engineering techniques involve manipulating individuals into providing sensitive information and do not pertain to the mechanical guessing of passwords. Exploiting software vulnerabilities focuses on finding and taking advantage of flaws in applications or systems rather than attempting to crack passwords directly.