CVE-2024-12649 is a vulnerability discovered in Canon printers' TrueType Font (TTF) interpreter, specifically in how the printer's embedded virtual machine executes font hinting instructions. The TTF format includes hinting commands that guide font rendering, implemented as a compact virtual machine supporting memory management, jumps, and branching. Researchers found that Canon's implementation fails to properly check for stack overflows during execution of these instructions, allowing a crafted malicious font to cause a stack buffer overflow. This overflow enables arbitrary code execution on the printer's ARM-based processor running Canon's proprietary DryOS operating system. The attack vector involves sending an XPS (XML Paper Specification) file to print, which contains the malicious TTF font. The rest of the XPS content is benign, making detection difficult. Exploitation requires only that a user print the malicious document, which can be delivered via email or messaging within the internal network, bypassing the need for internet-facing printer exposure. Once code execution is achieved, attackers can create network tunnels to pivot into the organization's network or exfiltrate printed documents, posing confidentiality and integrity risks. Canon has implemented some firmware protections like NX flags and DACR registers, but DryOS lacks modern memory protections such as ASLR or stack canaries, making it vulnerable to such exploits. Canon recommends firmware updates and restricting printer access via firewalls, but many organizations do not regularly update printer firmware or integrate printers into their security posture. This vulnerability highlights the risk posed by specialized office devices that often lack endpoint detection and response (EDR) coverage and comprehensive logging. The attack is notable for leveraging a seemingly innocuous file format and printer functionality to compromise organizational networks.

For European organizations, the impact of CVE-2024-12649 can be significant. Printers are ubiquitous in offices and often connected to internal networks with broad access privileges, yet they typically lack robust security controls and monitoring. Exploitation can lead to unauthorized code execution on the printer, enabling attackers to establish footholds within the network. This can facilitate lateral movement to critical servers and workstations, potentially leading to data breaches, intellectual property theft, or disruption of business operations. Sensitive printed materials, such as legal documents, contracts, or confidential reports, could be intercepted or exfiltrated, causing severe confidentiality violations. The attack requires minimal user interaction—only printing a malicious document—making social engineering feasible. The lack of firmware update processes for printers in many organizations increases exposure. Additionally, the vulnerability can be exploited without internet-facing exposure if an attacker can deliver the malicious file internally, increasing risk from insider threats or phishing campaigns. The medium severity rating understates the potential for network compromise and data leakage, especially in sectors like legal, finance, healthcare, and government where printed information is sensitive. The threat also underscores the need to secure non-traditional endpoints and networked devices beyond standard IT assets.

1. Immediately apply Canon's official firmware updates that address CVE-2024-12649 and related vulnerabilities. Establish a formal process for regular printer firmware management across all networked devices. 2. Segment the network to isolate printers from critical systems and restrict their ability to initiate outbound connections. Use VLANs and firewall rules to limit printer communication to only authorized devices and services. 3. Disable all unused services and protocols on printers to reduce the attack surface. 4. Enforce unique, complex administrator passwords on each printer to prevent unauthorized configuration changes. 5. Implement strict email and messaging security controls to detect and block malicious attachments, especially XPS files containing embedded fonts. 6. Train employees to recognize suspicious print requests and verify the source before printing documents received via email or messaging. 7. Integrate printers into the organization's security monitoring infrastructure, including network traffic analysis and SIEM correlation, to detect anomalous printer behavior or unexpected network connections. 8. Deploy endpoint detection and response (EDR) solutions on all computers and servers, and consider specialized monitoring for networked office devices. 9. Regularly audit and inventory all network-connected devices, including printers, to ensure security policies are enforced uniformly. 10. Restrict printer access to internal networks only, and block direct internet exposure via firewalls or VPNs.