CVE-2021-47664 in Franka Emika Robot
Summary
by MITRE • 04/24/2025
Due to improper authentication mechanism an unauthenticated remote attacker can enumerate valid usernames.
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Analysis
by VulDB Data Team • 04/24/2025
This vulnerability represents a critical authentication flaw that undermines the security posture of affected systems by enabling unauthorized enumeration of valid user accounts. The improper authentication mechanism allows remote attackers to systematically discover legitimate usernames without requiring valid credentials or prior access to the system. Such a vulnerability directly violates fundamental security principles and creates a significant attack surface that can be exploited by malicious actors to conduct targeted attacks against specific user accounts. The flaw exists within the authentication subsystem where the system fails to implement proper rate limiting, account lockout mechanisms, or consistent response handling that would normally prevent such enumeration attempts.
The technical implementation of this vulnerability stems from the application's failure to maintain consistent error responses when processing authentication requests for usernames that do not exist versus those that do exist. When an attacker submits a username to the authentication endpoint, the system provides different response behaviors based on whether the account exists in the database. This differential response pattern allows attackers to determine valid usernames through iterative testing and response analysis, effectively creating a user enumeration attack vector. The vulnerability aligns with CWE-305 authentication weakness and specifically relates to improper authentication mechanisms that fail to provide consistent feedback to unauthorized users. This type of information disclosure through response manipulation falls under the category of timing attacks and response-based enumeration techniques.
The operational impact of CVE-2021-47664 extends beyond simple username enumeration, as it enables attackers to conduct more sophisticated social engineering campaigns, targeted credential stuffing attacks, and brute force attempts against specific accounts. Once valid usernames are identified, attackers can focus their efforts on these accounts, significantly increasing the probability of successful compromise compared to random account guessing. The vulnerability particularly affects systems where user enumeration is not properly mitigated, including web applications, authentication services, and identity management platforms. This weakness can be exploited in conjunction with other vulnerabilities to create a complete attack chain, as demonstrated in the ATT&CK framework under the credential access and reconnaissance phases. Organizations may experience increased account lockout incidents, unauthorized access attempts, and potential data breaches when this vulnerability is exploited in the wild.
Mitigation strategies for this vulnerability require implementing consistent authentication responses regardless of whether a username exists in the system. Organizations should deploy rate limiting mechanisms to prevent rapid enumeration attempts, implement account lockout policies after multiple failed authentication attempts, and ensure that all authentication endpoints return identical error messages for both valid and invalid usernames. The implementation should follow security best practices such as those outlined in NIST SP 800-63B and ISO/IEC 29115 standards for authentication and access control. Additional protective measures include deploying intrusion detection systems to monitor for enumeration patterns, implementing multi-factor authentication to add additional security layers, and conducting regular security testing to identify similar authentication weaknesses. Organizations should also consider implementing account provisioning controls that prevent unauthorized users from creating accounts with predictable naming conventions that could facilitate enumeration attacks.