CVE-2006-0189 in Softphone
Summary
by MITRE
Buffer overflow in eStara Softphone 3.0.1.14 through 3.0.1.46 allows remote attackers to execute arbitrary code via a long attribute (aka "a") field in the SDP data of a SIP packet on UDP port 5060.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2006-0189 represents a critical buffer overflow condition affecting eStara Softphone versions 3.0.1.14 through 3.0.1.46. This flaw exists within the Session Initiation Protocol (SIP) processing functionality of the softphone application, specifically when handling Session Description Protocol data structures that contain excessively long attribute fields. The vulnerability manifests when a remote attacker crafts a malicious SIP packet containing an oversized "a" field attribute in the SDP data portion of the packet, which is then processed by the vulnerable softphone application. The issue occurs at UDP port 5060, which is the standard port for SIP communications, making this attack vector particularly dangerous as it can be exploited through normal SIP traffic without requiring any special authentication or privileged access.
The technical implementation of this buffer overflow stems from inadequate input validation within the eStara Softphone's SIP parser component. When the application receives a SIP packet containing an oversized attribute field in the SDP data, the software fails to properly bounds-check the length of the incoming data before copying it into a fixed-size buffer in memory. This classic buffer overflow condition allows an attacker to overwrite adjacent memory locations, potentially including return addresses, function pointers, or other critical program state information. The vulnerability is particularly concerning because it operates at the application layer of the network stack, where attackers can leverage the standard SIP protocol to deliver malicious payloads without requiring any specialized network access or privileged accounts. The buffer overflow can be triggered by sending a specially crafted SIP packet that includes a long attribute field, causing the application to write beyond the allocated buffer boundaries and potentially execute arbitrary code with the privileges of the softphone process.
The operational impact of this vulnerability extends beyond simple remote code execution, as it fundamentally compromises the integrity and availability of the affected system. When successfully exploited, the buffer overflow can allow attackers to gain complete control over the vulnerable softphone application, potentially enabling them to execute malicious code, establish persistent backdoors, or use the compromised system as a launching point for further attacks within the network. The vulnerability affects any system running the vulnerable eStara Softphone versions, making it particularly dangerous in enterprise environments where SIP-based communication systems are commonly deployed. Attackers can leverage this vulnerability to perform reconnaissance activities, escalate privileges, or use the compromised system to target other network resources. The attack vector is particularly stealthy since it uses standard SIP protocol traffic, making it difficult to detect through conventional network monitoring tools that might not flag the malicious packets as suspicious. The vulnerability also impacts system availability, as successful exploitation could cause the softphone application to crash or behave unpredictably, leading to service disruption for legitimate users.
Mitigation strategies for this vulnerability should focus on immediate patching and network-level controls. The most effective approach is to upgrade to a patched version of eStara Softphone that addresses the buffer overflow condition in the SIP parser implementation. Organizations should also implement network segmentation and access controls to limit exposure to the vulnerable UDP port 5060, while monitoring for unusual SIP traffic patterns that might indicate exploitation attempts. Network-based intrusion detection systems should be configured to detect and alert on malformed SIP packets containing unusually long attribute fields. Additionally, administrators should consider implementing SIP-specific firewalls or proxies that can validate and sanitize SIP traffic before it reaches the vulnerable softphone applications. From a security standards perspective, this vulnerability aligns with CWE-121, which describes the classic stack-based buffer overflow condition, and relates to ATT&CK technique T1203, which covers legitimate credentials and remote access tools. Organizations should also consider implementing principle of least privilege controls for SIP applications and regularly audit their SIP-based communication infrastructure to identify and remediate similar vulnerabilities in other components of their VoIP systems.