CVE-2009-2435 in Lotus Instant Messaging
Summary
by MITRE
The Sametime server in IBM Lotus Instant Messaging and Web Conferencing 6.5.1 generates error messages for a failed logon attempt with different time delays depending on whether the user account exists, which allows remote attackers to enumerate valid usernames.
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Analysis
by VulDB Data Team • 12/07/2017
The vulnerability described in CVE-2009-2435 represents a classic timing attack scenario that exploits information disclosure through inconsistent response delays in the IBM Lotus Instant Messaging and Web Conferencing server implementation. This weakness specifically affects version 6.5.1 of the Sametime server component, where the system exhibits differential timing behavior during authentication attempts. When a user attempts to log on to the system, the server responds with varying delays based on whether the username exists in the system, creating a predictable pattern that attackers can exploit to determine valid user accounts.
The technical flaw stems from the server's implementation of authentication logic where it does not maintain consistent response times regardless of the authentication outcome. When an invalid username is provided, the server may perform additional validation checks or database queries that introduce measurable delays compared to when a valid username is submitted but an incorrect password is provided. This timing variation creates a side-channel attack vector that directly violates fundamental security principles of constant-time execution and uniform response behavior. The vulnerability falls under the category of information disclosure through timing variations, which is classified as CWE-203 in the Common Weakness Enumeration catalog.
From an operational perspective, this vulnerability enables remote attackers to conduct automated username enumeration attacks against the Sametime server without requiring prior knowledge of valid accounts. Attackers can systematically test usernames by measuring response times to identify which accounts exist within the system, potentially leading to subsequent credential brute force attacks or targeted social engineering efforts. The impact extends beyond simple account enumeration since valid user identification can serve as a foundation for more sophisticated attacks, including password spraying, credential stuffing, or privilege escalation attempts. This vulnerability directly maps to techniques described in the MITRE ATT&CK framework under the credential access and discovery phases, where adversaries seek to identify valid accounts within target systems.
The security implications of this vulnerability are significant for organizations relying on IBM Lotus Instant Messaging and Web Conferencing, as it provides attackers with a low-effort method to gather intelligence about user populations. The timing differences typically range from milliseconds to seconds, making automated detection feasible through simple network monitoring tools or custom scripts. Organizations may face reputational damage and increased risk of successful compromise when this vulnerability is exploited, particularly in environments where user enumeration can lead to targeted attacks against high-value accounts or when combined with other reconnaissance activities. The vulnerability demonstrates a fundamental flaw in the server's authentication design that violates the principle of least information disclosure, where systems should not reveal information about their internal state that could aid attackers in their operations. Organizations should implement proper rate limiting, account lockout mechanisms, and consistent authentication response times to mitigate this class of vulnerability, while also considering the broader security implications of timing-based information leakage in network services.