Malicious code implanted in network printers may cause malfunction or information leakage. This attack may be achieved through the following channels: 1. **Default password**: Many network printers are factory set with default account and password, and these default credentials are usually easy to obtain. If the administrator does not change the password in time, the attacker can easily access the printer's management interface. 2. **Network vulnerability**: Any unpatched system vulnerability may become an attack entry point. Attackers can scan the network for known security vulnerabilities in printers and exploit them. 3. **Malicious firmware updates**: Attackers may spread malicious code by forging firmware updates. Users may inadvertently install malware when downloading and installing firmware from unverified channels. 4. **Unprotected ports**: Through open ports, attackers may directly access the printer. Some protocols such as FTP, Telnet or SMB may be open by default, increasing the risk of attack. 5. **Phishing emails**: Attackers may send phishing emails containing malicious attachments or links to lure network administrators or users to click on them, thereby executing malicious code. 6. **Malicious documents**: Attackers may create specially crafted documents that, once sent to the printer for printing, will trigger vulnerabilities in the printer. 7. **Physical access**: If an attacker has physical access to the printer, malicious code can be directly uploaded and executed through the USB port or other connection interface. 8. **Social engineering**: A skilled attacker may gain access by contacting the person responsible for managing the printer and using fraudulent means. To prevent these attacks, it is recommended to take appropriate security measures, such as updating passwords, regularly updating firmware, closing unused ports and services, using encryption protocols, and providing network security training to employees.