What type of malware is known to damage the file system if accessed by anyone other than the original user?

The correct answer, a rootkit, is a type of malware specifically designed to gain unauthorized access to a computer system and conceal its presence or the presence of other software. Rootkits often operate at a low level within the operating system, enabling them to manipulate core system processes and access data without detection. If accessed by anyone other than the original user, a rootkit can cause significant damage to the file system, often altering or corrupting files essential for the operating system or applications to function correctly.

Rootkits are particularly concerning because they typically allow attackers to maintain persistent access to a system, making them difficult to remove without specialized tools. They can also facilitate the activation of other malicious software, leading to further compromise of the system.

In contrast, viruses often require user action to spread and may not necessarily damage the file system upon access. Worms are self-replicating malware that spread across networks without user intervention, while Trojan horses masquerade as legitimate software but do not typically cause damage unless executed by the user. Thus, while all these malware types can be harmful, rootkits stand out for their capability to inflict damage on the file system when accessed by unauthorized users.