CVE-2017-12260 in Small Business SPA50x
Summary
by MITRE
A vulnerability in the implementation of Session Initiation Protocol (SIP) functionality in Cisco Small Business SPA50x, SPA51x, and SPA52x Series IP Phones could allow an unauthenticated, remote attacker to cause an affected device to become unresponsive, resulting in a denial of service (DoS) condition. The vulnerability is due to the improper handling of SIP request messages by an affected device. An attacker could exploit this vulnerability by using formatted specifiers in a SIP payload that is sent to an affected device. A successful exploit could allow the attacker to cause the affected device to become unresponsive, resulting in a DoS condition that persists until the device is restarted manually. This vulnerability affects Cisco Small Business SPA50x, SPA51x, and SPA52x Series IP Phones that are running firmware release 7.6.2SR1 or earlier. Cisco Bug IDs: CSCvc63986.
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Analysis
by VulDB Data Team • 01/19/2021
The vulnerability identified as CVE-2017-12260 represents a critical denial of service weakness in Cisco Small Business IP phone series that impacts the Session Initiation Protocol functionality. This flaw specifically affects the SPA50x, SPA51x, and SPA52x series devices operating with firmware versions 7.6.2SR1 or earlier, creating a significant risk for small business networks that rely on these communication devices for voice services. The vulnerability stems from inadequate input validation within the SIP message processing subsystem, where the affected devices fail to properly sanitize incoming SIP requests before processing them.
The technical exploitation of this vulnerability leverages formatted specifiers within SIP payload data to trigger memory corruption or stack manipulation within the device's processing routines. This improper handling of SIP request messages creates a condition where maliciously crafted SIP packets can cause the device's memory management system to behave unpredictably, ultimately leading to system instability and complete service disruption. The attack vector requires no authentication credentials, making it particularly dangerous as any remote attacker can potentially exploit this weakness without requiring prior access to the network. The vulnerability operates at the application layer of the network stack, specifically targeting the SIP protocol implementation that governs voice communication sessions.
The operational impact of this vulnerability extends beyond simple service interruption, as the affected devices require manual restart to restore functionality, creating extended downtime for business communications. This DoS condition can severely disrupt business operations, particularly in environments where reliable voice communication is critical for customer service, emergency response, or collaborative work environments. Network administrators may face challenges in identifying the root cause of service outages, as the symptoms manifest as complete device unresponsiveness rather than more specific error conditions. The persistence of the DoS condition until manual intervention is required creates additional operational overhead and potential business disruption.
Security practitioners should implement immediate mitigations including firmware updates to versions containing the patched SIP processing logic, network segmentation to isolate affected devices, and monitoring of SIP traffic for anomalous patterns. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation that can lead to system instability. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for network denial of service, where adversaries leverage protocol implementation weaknesses to disrupt services. Organizations should also consider implementing rate limiting on SIP traffic and establishing incident response procedures specifically for identifying and addressing SIP-based DoS attacks. The vulnerability underscores the importance of maintaining up-to-date firmware for network infrastructure devices and demonstrates how seemingly minor implementation flaws in communication protocols can have significant operational consequences.