How can antivirus software help in the case of ZeuS malware?

Antivirus software is designed to detect and remove malicious software, including ZeuS malware, which is known for targeting financial data and conducting various forms of cybercrime. By scanning files for characteristics of ZeuS, antivirus software can identify known signatures and behaviors associated with this malware. This process involves comparing the files on a system against a database of known threats, which enables the antivirus to proactively identify and neutralize the ZeuS threat before it can cause harm.

In this context, the ability to scan files is critical, as it directly addresses the root of the problem—malicious code residing on a user's system. Once detected, the antivirus can quarantine or remove the files associated with ZeuS, consequently protecting the user’s data and finances from being compromised.

The other options do not specifically address the nature of malware detection and response. Blocking all internet traffic can prevent legitimate use of applications and services, backing up data does not eliminate the risk of infection, and restricting user access to external sites may mitigate exposure but does not actively target malware present on the system. Thus, scanning files is the most effective means of combating ZeuS malware through antivirus software.