CVE-2009-4409 in SEIL
Summary
by MITRE
The (1) CHAP and (2) MS-CHAP-V2 authentication capabilities in the PPP Access Concentrator (PPPAC) function in Internet Initiative Japan SEIL/B1 firmware 1.00 through 2.52 use the same challenge for each authentication attempt, which allows remote attackers to bypass authentication via a replay attack.
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Analysis
by VulDB Data Team • 12/26/2017
The vulnerability described in CVE-2009-4409 represents a critical weakness in the authentication mechanisms of Internet Initiative Japan SEIL/B1 firmware versions 1.00 through 2.52. This issue specifically affects the Point-to-Point Protocol Access Concentrator functionality where both Challenge Handshake Authentication Protocol and Microsoft Challenge Handshake Authentication Protocol version 2 implementations suffer from predictable challenge generation. The flaw stems from the firmware's failure to properly randomize authentication challenges, creating a deterministic pattern that attackers can exploit to gain unauthorized access to network resources. This weakness directly violates fundamental security principles of authentication protocols where challenge-response mechanisms rely on unpredictable values to prevent replay attacks. The vulnerability falls under CWE-310, which specifically addresses cryptographic weaknesses related to predictable random number generation and insufficient entropy in security protocols. From an operational perspective, this vulnerability creates a significant risk for network administrators as it allows remote attackers to bypass authentication entirely by simply replaying previously captured challenge-response pairs. The attack vector is particularly concerning because it requires no local access or specialized equipment beyond network monitoring capabilities, making it accessible to a wide range of threat actors. The impact extends beyond simple unauthorized access to include potential data breaches, privilege escalation, and lateral movement within network environments where these devices operate. The vulnerability demonstrates a failure in the principle of least privilege and authentication integrity, as the system cannot properly verify the authenticity of connection attempts. Organizations using affected SEIL/B1 firmware face substantial risk of unauthorized network access and potential compromise of sensitive data. The specific nature of the flaw places this vulnerability in the ATT&CK framework under T1110.001 - Brute Force: Password Guessing and T1110.003 - Brute Force: Credential Stuffing, as attackers can leverage the predictable challenge responses to bypass authentication mechanisms without requiring extensive computational resources. The issue also aligns with T1078 - Valid Accounts, as successful exploitation would allow attackers to establish persistent access using legitimate credentials obtained through the authentication bypass. This vulnerability highlights the critical importance of proper cryptographic implementation in network infrastructure devices and demonstrates how seemingly minor flaws in authentication protocols can have significant security implications. The predictable challenge generation creates a scenario where authentication becomes effectively meaningless, as the security mechanism fails to provide the necessary entropy required for secure challenge-response operations. Network security teams should prioritize immediate remediation of affected devices through firmware updates or replacement, as the vulnerability provides attackers with a straightforward path to unauthorized access without requiring advanced technical skills or specialized tools.
The technical implementation flaw in the SEIL/B1 firmware stems from improper challenge generation algorithms that consistently use identical challenge values for each authentication attempt. This deterministic approach eliminates the cryptographic strength required for secure authentication protocols, as challenges should be unique and unpredictable for each session to prevent replay attacks. The vulnerability represents a fundamental failure in the cryptographic design of the authentication mechanisms, where the security model assumes that challenges must be generated with sufficient entropy to ensure uniqueness. According to industry standards, this type of vulnerability would be classified under the cryptographic weakness category, specifically addressing the lack of proper random number generation and insufficient entropy in security-critical components. The implementation error affects both CHAP and MS-CHAP-V2 protocols simultaneously, indicating a systemic issue within the firmware's authentication subsystem rather than isolated protocol-specific problems. This dual impact increases the severity of the vulnerability as it affects multiple authentication mechanisms that organizations might rely upon for network access control. The predictable nature of the challenges means that an attacker who captures a single authentication exchange can replay that challenge-response pair against any subsequent authentication attempts, effectively breaking the authentication process entirely. The vulnerability's exploitation requires only network monitoring capabilities and does not demand sophisticated attack infrastructure, making it particularly dangerous for organizations with limited security resources. The security implications extend to potential data exfiltration, service disruption, and unauthorized access to network resources that should be protected by the authentication mechanisms. From a compliance perspective, this vulnerability would likely result in non-compliance with security standards such as NIST SP 800-53 and ISO/IEC 27001, which mandate the implementation of secure authentication protocols with proper cryptographic practices. The vulnerability demonstrates a clear gap in the security testing and validation processes that should have identified and corrected the predictable challenge generation before deployment in production environments.
Organizations affected by CVE-2009-4409 must implement immediate remediation strategies to address the authentication bypass vulnerability. The primary mitigation involves upgrading to firmware versions that properly implement randomized challenge generation for both CHAP and MS-CHAP-V2 protocols, ensuring that each authentication attempt uses unique and unpredictable challenge values. Network administrators should conduct comprehensive inventory assessments to identify all affected SEIL/B1 devices and prioritize their remediation based on risk exposure and network criticality. The vulnerability's impact assessment should include analysis of network access controls, authentication logs, and potential compromise indicators that may have occurred during the vulnerability's active period. Security teams should implement monitoring procedures to detect unauthorized access attempts and authentication failures that could indicate exploitation attempts against this vulnerability. The remediation process must also include verification procedures to confirm that the firmware updates have properly implemented secure challenge generation mechanisms. Organizations should consider implementing additional security controls such as network segmentation, access control lists, and enhanced monitoring to reduce the potential impact of any successful exploitation attempts. The vulnerability's persistence in multiple firmware versions indicates a systemic issue that requires thorough review of the device's security implementation and testing processes. Security professionals should also consider implementing network-based intrusion detection systems that can identify and alert on replay attack patterns that may be used to exploit this vulnerability. The remediation timeline should account for potential compatibility issues with existing network configurations and ensure that updated firmware maintains required functionality while addressing the authentication weakness. Organizations must also document the vulnerability and remediation efforts for compliance purposes and to establish a baseline for future security assessments of similar network infrastructure devices. The vulnerability serves as a reminder of the importance of proper cryptographic implementation in network security devices and the necessity of thorough security testing before deployment in production environments.