CVE-2002-1553 in ONS15327
Summary
by MITRE
Cisco ONS15454 and ONS15327 running ONS before 3.4 allows remote attackers to modify the system configuration and delete files by establishing an FTP connection to the TCC, TCC+ or XTC using a username and password that does not exist.
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Analysis
by VulDB Data Team • 05/29/2019
The vulnerability described in CVE-2002-1553 represents a critical authentication flaw affecting Cisco ONS 15454 and ONS 15327 optical network systems operating with software versions prior to 3.4. This issue stems from improper handling of FTP connections to the Transport Control Card (TCC), TCC+, or eXtended Transport Card (XTC) components within these network devices. The flaw allows remote attackers to exploit the system by establishing an FTP connection using non-existent credentials, thereby gaining unauthorized access to critical system configuration files and enabling destructive operations including file deletion and configuration modification.
The technical implementation of this vulnerability demonstrates a classic authentication bypass mechanism where the system fails to properly validate user credentials during FTP authentication processes. When an attacker establishes an FTP connection to the TCC, TCC+, or XTC components using invalid username and password combinations, the system incorrectly grants access privileges. This misconfiguration stems from insufficient input validation and authentication checks within the FTP service implementation, allowing unauthorized users to manipulate the system's operational parameters. The vulnerability specifically affects the authentication mechanism of the FTP service running on these network cards, where the system's response to invalid credentials does not properly enforce access restrictions.
The operational impact of this vulnerability is severe and multifaceted, potentially compromising the integrity and availability of critical network infrastructure. Attackers can leverage this flaw to modify system configurations, potentially disrupting network operations or creating backdoors for future unauthorized access. The ability to delete files on the system components represents a particularly dangerous aspect, as it could lead to complete system compromise or denial of service conditions. Network administrators responsible for maintaining these optical transport systems face significant risks including unauthorized configuration changes that could affect network performance, security policies, or even cause complete service outages. The remote nature of the attack means that threat actors can exploit this vulnerability from anywhere on the network without requiring physical access to the equipment.
This vulnerability aligns with CWE-287, which addresses improper authentication issues in software systems, and represents a failure in the authentication mechanism that should have prevented access based on invalid credentials. From an ATT&CK framework perspective, this vulnerability maps to T1110.003 (Brute Force: Password Guessing) and T1068 (Exploitation for Privilege Escalation) techniques, as attackers can exploit weak authentication to gain elevated privileges. The vulnerability also demonstrates characteristics of T1484 (Domain Policy Modification) and T1078 (Valid Accounts) as unauthorized access to system components can lead to persistent access and configuration changes. Organizations implementing Cisco ONS systems should consider this vulnerability as part of their broader security posture assessment, particularly in environments where these legacy systems remain operational.
Mitigation strategies for CVE-2002-1553 primarily focus on immediate software updates and network segmentation measures. The most effective solution involves upgrading the affected Cisco ONS systems to software version 3.4 or later, which includes fixed authentication mechanisms for FTP services on TCC, TCC+, and XTC components. Network administrators should also implement strict network segmentation to isolate these critical systems from general network access, reducing the attack surface for remote exploitation attempts. Additional protective measures include disabling unnecessary FTP services when not required, implementing robust access control lists, and establishing monitoring procedures to detect unauthorized FTP connection attempts. Regular security assessments and vulnerability scanning should be conducted to identify any remaining systems that may be vulnerable to similar authentication bypass issues, ensuring comprehensive protection across the entire network infrastructure.