Antivirus

What Is Antivirus?

Antivirus functions as a security mechanism that detects and manages files infected with viruses by leveraging virus signature detection. Its primary objective is to safeguard network security by preventing data corruption, unauthorized permission modifications, and system crashes resulting from virus-infected files.

By utilizing an extensive and regularly updated database of virus signatures, the antivirus feature effectively shields intranet users and servers from potential compromises caused by these malicious files. To protect the network, an antivirus-enabled device is deployed at the network egress, actively identifying and eliminating viruses.

The Significance of Antivirus

Viruses represent a form of malicious code capable of propagating through email and file transfer protocols, often disguising themselves as attachments to application programs and files. These viruses engage in various harmful activities upon infecting hosts, posing significant threats to both the hosts and the overall network. Their detrimental actions range from resource exhaustion and malicious occupation of network bandwidth to unauthorized control over host permissions and the theft of user data. In some cases, viruses can even cause hardware corruption on the affected hosts.

As network technologies continue to advance, users are increasingly engaged in file transfers, downloads, and sharing, exposing them to unprecedented virus risks.

To address these concerns, network security devices such as firewalls or dedicated antivirus gateways are deployed at the network edge. By configuring the antivirus function on these devices, normal files are permitted to enter the intranet. However, once a virus-infected file is identified, the device promptly blocks it or notifies users of its presence.

The antivirus function configured on network security devices and the antivirus software installed on user hosts work in tandem to provide comprehensive protection. They operate at different locations and employ distinct antivirus signature databases, enabling them to collaborate effectively in securing both user hosts and the network.

Mechanism of Operation for Antivirus

The antivirus function consists of three main components that form its workflow.

1. Protocol identification: Viruses spread through various protocols like FTP, HTTP, SMTP, POP3, IMAP, NFS, and SMB. Each protocol involves file transfers in different directions, such as downloading, uploading, or both.

• File Transfer Protocol (FTP) is a widely used protocol for transferring files between an FTP client and server. Users can download files from and upload files to the FTP server, facilitating bidirectional file transfers.

• Hypertext Transfer Protocol (HTTP) is a common protocol primarily used for web browsing but also supports file transfers. With HTTP, clients (e.g., web browsers) can download files from servers and upload files to them, enabling two-way file transfers.

• Simple Mail Transfer Protocol (SMTP) is the predominant protocol for sending emails from a client to an email server, as well as between email servers. SMTP operates as a one-way push process, allowing file transfers in the form of email uploads (sending emails).

• Post Office Protocol 3 (POP3) is a client-side protocol used for retrieving emails from an email server. POP3 functions as a one-way pull process, enabling file transfers in the form of email downloads (receiving emails).

• Interactive Mail Access Protocol (IMAP) is a protocol that facilitates sending and receiving emails between clients and email servers. IMAP supports both downloading (receiving emails) and uploading (sending emails), allowing bidirectional file transfers and direct email operations on the server.

• Network File System (NFS) is a file sharing protocol commonly used in Linux systems. NFS enables file transfers in both directions, allowing users to upload and download files within the network.

• Server Message Block (SMB) is a file sharing protocol primarily used in Windows systems. SMB supports bidirectional file transfers, enabling users to upload and download files across the network.

2. Virus detection: The antivirus device analyzes files being transferred and compares their signatures with those stored in the virus signature database. If a match is found, indicating a virus-infected file, it proceeds to the antivirus module. If no match is detected, the file transfer is allowed to proceed.

3. Response and processing: Upon identifying a virus-infected file, the antivirus device initiates one of the following actions:

• Alert: The virus-infected file is allowed to pass through, and relevant virus logs are recorded for analysis by the network administrator, who can then take appropriate measures.

• Block: The virus-infected file is prevented from passing through, and virus logs are recorded for further analysis by the network administrator, enabling them to implement necessary actions.

Highly Effective Approaches for Antivirus Protection

To ensure effective antivirus protection, it is crucial to establish a comprehensive antivirus system and enhance the security awareness of network users. Here are the key aspects:

1. Install antivirus software on all network devices within the intranet, including computers, servers, and connected mobile phones. This ensures that every terminal is equipped with antivirus capabilities.

2. Deploy network security devices, such as firewalls or dedicated antivirus gateways, at critical network locations like Internet egress points and server area egresses. This prevents the propagation of viruses at the network layer. In highly secure intranets, consider deploying network security devices at each LAN egress to prevent virus transmission between LANs.

3. Utilize a Network Management System (NMS) for centralized management of antivirus software on terminals and network security devices. The NMS facilitates timely updates of virus signature databases across the network.

4. Foster a culture of security awareness among all users. Encourage them to exercise caution when interacting with external emails by avoiding clicking on attachments or links. Additionally, educate users about the risks associated with visiting illegal websites that may harbor viruses.