CVE-2021-21539 in iDRAC9
Summary
by MITRE • 05/01/2021
Dell EMC iDRAC9 versions prior to 4.40.00.00 contain a Time-of-check Time-of-use (TOCTOU) race condition vulnerability. A remote authenticated attacker could potentially exploit this vulnerability to gain elevated privileges when a user with higher privileges is simultaneously accessing iDRAC through the web interface.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/07/2021
The CVE-2021-21539 vulnerability represents a critical time-of-check time-of-use race condition flaw in Dell EMC iDRAC9 management interfaces. This vulnerability exists in firmware versions prior to 4.40.00.00 and demonstrates a classic concurrency issue where the system's validation logic occurs at a different point in time than the actual execution phase. The flaw enables a remote authenticated attacker to exploit a temporal window between when access permissions are checked and when the actual resource manipulation occurs, creating a potential pathway for privilege escalation attacks.
The technical implementation of this vulnerability stems from improper synchronization mechanisms within the iDRAC9 web interface authentication and authorization processes. When a user with elevated privileges accesses the management interface simultaneously, the system's race condition allows an attacker to manipulate the state between the permission verification and the actual operation execution. This temporal discrepancy creates an opportunity for malicious actors to inject unauthorized commands or access restricted functionality during the brief window when the system's security checks are completed but before the operation is fully executed.
From an operational impact perspective, this vulnerability poses significant risks to enterprise infrastructure security as it allows remote attackers with valid credentials to potentially escalate their privileges without requiring additional authentication methods. The attack vector requires only authenticated access to the iDRAC9 interface, making it particularly dangerous in environments where administrative credentials might be compromised through phishing, credential theft, or other attack vectors. The vulnerability could enable attackers to gain full administrative control over the managed server, potentially leading to data breaches, system compromise, or further lateral movement within the network infrastructure.
Security professionals should note that this vulnerability aligns with CWE-362, which specifically addresses race conditions in software systems where the state changes between the check and use phases. The attack pattern follows typical privilege escalation techniques described in the MITRE ATT&CK framework under the privilege escalation tactic, specifically targeting the use of legitimate credentials for unauthorized access. Organizations should implement immediate remediation by upgrading iDRAC9 firmware to version 4.40.00.00 or later, while also monitoring for suspicious authentication patterns and implementing network segmentation to limit access to management interfaces. Additionally, security teams should conduct comprehensive vulnerability assessments to identify any other systems running vulnerable iDRAC9 versions and establish continuous monitoring for potential exploitation attempts.