CVE-2002-1935 in xpressa
Summary
by MITRE
Pingtel Xpressa 1.2.5 through 2.0.1 uses predictable (1) Call-ID, (2) CSeq, and (3) "To" and "From" SIP URL values in a Session Identification Protocol (SIP) request, which allows remote attackers to avoid registering with the SIP registrar.
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Analysis
by VulDB Data Team • 07/06/2024
The vulnerability identified as CVE-2002-1935 affects Pingtel Xpressa versions 1.2.5 through 2.0.1, representing a critical weakness in the Session Initiation Protocol implementation that undermines the security of voice over IP communications. This flaw resides in the predictable generation of essential SIP identifiers that are fundamental to session management and authentication within the SIP framework. The vulnerability specifically targets three critical components of SIP requests: Call-ID, CSeq, and the To and From SIP URL values, which together form the foundation of session identification and tracking mechanisms.
The technical flaw stems from the implementation of weak random number generation or deterministic algorithms in the SIP message construction process. When SIP requests are generated, the system uses predictable sequences for these identifiers rather than cryptographically secure random values, creating a scenario where an attacker can anticipate and reproduce these values. This predictability allows malicious actors to craft legitimate-looking SIP messages that bypass normal registration and authentication procedures, effectively enabling unauthorized access to the SIP infrastructure. The vulnerability operates at the application layer and specifically targets the SIP protocol stack, making it particularly dangerous as it undermines the core security assumptions of the communication system.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can enable a wide range of malicious activities including session hijacking, call interception, and potentially full system compromise. Attackers can exploit this weakness to establish unauthorized SIP sessions without proper registration, allowing them to monitor communications, redirect calls, or even initiate fraudulent sessions. This vulnerability directly violates the fundamental security principle of authentication and authorization within SIP communications, creating a backdoor that bypasses normal registration processes. The attack surface is particularly concerning as it affects the core registration mechanism of SIP systems, potentially allowing attackers to impersonate legitimate users and gain unauthorized access to voice communication services.
Mitigation strategies for CVE-2002-1935 require immediate implementation of cryptographic random number generation for all SIP identifier fields, ensuring that Call-ID, CSeq, and To/From URL values are generated using secure entropy sources. Organizations should implement proper session management controls and regularly audit their SIP implementations for predictable value generation. The vulnerability aligns with CWE-330, which addresses insufficient entropy in random number generation, and can be categorized under ATT&CK technique T1566 for credential harvesting through social engineering or protocol manipulation. System administrators should upgrade to patched versions of Pingtel Xpressa, implement network monitoring to detect anomalous SIP traffic patterns, and establish proper access controls for SIP registration servers. Additionally, organizations should consider implementing SIP-specific security measures such as authentication challenges, secure registration protocols, and regular security assessments of their VoIP infrastructure to prevent similar vulnerabilities from emerging in other components of their communication systems.