CVE-2024-20450 in Small Business IP Phones
Summary
by MITRE • 08/07/2024
Multiple vulnerabilities in the web-based management interface of Cisco Small Business SPA300 Series IP Phones and Cisco Small Business SPA500 Series IP Phones could allow an unauthenticated, remote attacker to execute arbitrary commands on the underlying operating system with root privileges.
These vulnerabilities exist because incoming HTTP packets are not properly checked for errors, which could result in a buffer overflow. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to overflow an internal buffer and execute arbitrary commands at the root privilege level.
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Analysis
by VulDB Data Team • 08/24/2024
The vulnerability CVE-2024-20450 represents a critical security flaw in Cisco Small Business SPA300 and SPA500 series IP phones that exposes these devices to remote command execution attacks. This vulnerability resides within the web-based management interface of these telephony devices, which are commonly deployed in small business environments for voice communication. The affected devices operate on embedded operating systems that are particularly susceptible to buffer overflow conditions when processing malformed HTTP requests. The flaw stems from inadequate input validation mechanisms within the HTTP processing stack, specifically failing to properly validate incoming packet data before processing. This oversight creates a pathway for attackers to manipulate the device's operating system through carefully crafted HTTP requests that trigger memory corruption. The vulnerability is particularly concerning because it allows unauthenticated remote exploitation, meaning attackers do not require legitimate credentials to attempt the attack. The buffer overflow condition occurs when the device processes HTTP packets that exceed expected buffer boundaries, leading to memory corruption that can be leveraged to execute arbitrary code with root privileges. This privilege escalation capability fundamentally compromises the device's security posture, as attackers can gain complete control over the underlying operating system. The impact extends beyond simple device compromise to include potential network infiltration, data exfiltration, and disruption of critical communication services within the affected organization.
The technical exploitation of this vulnerability aligns with common software security weaknesses categorized under CWE-121, which addresses buffer overflow conditions in heap-based memory allocations. The flaw demonstrates characteristics of CWE-122, heap-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations. Additionally, this vulnerability maps to ATT&CK technique T1059.007 for command and scripting interpreter, specifically HTTP-based command execution, and T1566.001 for spearphishing via web application. The exploitation process involves crafting HTTP requests that contain malicious payloads designed to overflow buffers within the device's memory space. These payloads typically contain shellcode or executable instructions that leverage the buffer overflow to gain code execution privileges. The attack surface is particularly broad as the vulnerability affects multiple device models within the Cisco Small Business product line, increasing the potential attack surface for threat actors. Network-based exploitation is possible since the vulnerability exists in the web interface, which is accessible over HTTP ports without requiring authentication. The device's embedded operating system architecture, designed for minimal resource consumption, often lacks modern security mitigations such as stack canaries, address space layout randomization, or data execution prevention mechanisms, making exploitation more straightforward.
The operational impact of CVE-2024-20450 extends far beyond simple device compromise, creating significant risk for organizations relying on these telephony systems for business-critical communications. Once exploited, attackers can gain complete administrative control over the affected devices, enabling them to modify phone configurations, redirect calls, intercept voice communications, or even use the devices as entry points for broader network attacks. The vulnerability's ability to execute commands with root privileges means attackers can install persistent backdoors, modify system files, or disable security features within the device. Organizations may experience service disruption as attackers can manipulate call routing, potentially leading to communication failures or unauthorized access to sensitive conversations. The compromise of these devices also poses risks to network security infrastructure, as IP phones often serve as network endpoints that can be leveraged for lateral movement within corporate networks. The vulnerability affects small business environments where network security monitoring may be limited, making detection and response more challenging. Attackers can potentially use these compromised devices to establish command and control channels, monitor network traffic, or conduct reconnaissance activities against other network segments. The attack vector is particularly dangerous because it requires no authentication, meaning any attacker with network access can attempt exploitation. The vulnerability's presence in widely deployed consumer-grade networking equipment increases the likelihood of successful exploitation, as these devices often lack the robust security monitoring and patch management capabilities found in enterprise-grade systems.
Mitigation strategies for CVE-2024-20450 should include immediate network segmentation to isolate affected devices from critical network infrastructure, implementing network access controls to restrict HTTP access to these devices, and applying vendor-provided security patches as soon as they become available. Organizations should consider disabling the web-based management interface when not actively required, or alternatively, restricting access to the interface through firewalls and access control lists. Network monitoring should be enhanced to detect anomalous HTTP traffic patterns that might indicate exploitation attempts, including unusual request sizes, malformed headers, or repeated connection attempts to the affected ports. Security teams should implement regular vulnerability scanning to identify other potentially affected devices within their network infrastructure, as the same vulnerability may exist in other Cisco Small Business products. Device firmware updates should be prioritized, with immediate patching of all affected devices to address the underlying buffer overflow condition. Network administrators should consider implementing intrusion detection systems that can identify and alert on exploitation attempts targeting this specific vulnerability. The remediation process should include comprehensive testing of patches in controlled environments before deployment to ensure no disruption to critical telephony services. Additionally, organizations should conduct security awareness training for staff to recognize potential social engineering attempts that might accompany exploitation efforts, as attackers may attempt to gain initial access through phishing or other deceptive means. Regular security audits should be performed to verify that the mitigation measures remain effective and that no new vulnerabilities have been introduced through device configuration changes or network modifications.