What characteristic is shared by both viruses and worms?

Both viruses and worms are classified as types of malware known for their ability to self-replicate. This characteristic allows them to reproduce and spread without needing human intervention once they have infiltrated a system or network.

Viruses attach themselves to legitimate programs or files, and when the infected program is executed, the virus activates and can spread to other files or systems. Worms, on the other hand, are standalone malware that replicate themselves across networks, often exploiting vulnerabilities in software or systems to propagate. The self-replication capability of both types of malware poses significant risks to systems and networks, allowing them to cause widespread damage by rapidly multiplying and infecting other devices.

The other options include characteristics that are either not universally applicable to both viruses and worms or are not defining traits. For example, not all viruses and worms can erase user data, nor do they necessarily encrypt files upon infection. Additionally, viruses and worms do not always require explicit user permissions to execute, as many can spread and activate without user action, particularly in contexts where users are unaware of their presence.