CVE-2021-21557 is a high-severity vulnerability affecting Dell PowerEdge Server BIOS and certain Dell Precision Rack BIOS versions. This vulnerability allows an out-of-bounds array access, which can be exploited by a local malicious user with high privileges. The consequences include potential denial of service, arbitrary code execution, or information disclosure in System Management Mode.
The CVSS score for this vulnerability is 8.1, indicating a high severity level that organizations must take seriously. The risk to organizations includes significant operational disruptions or unauthorized access to sensitive information, making remediation critical.
Currently, there are no confirmed public exploits available; however, the potential impact of this vulnerability necessitates immediate attention. Organizations using affected systems should prioritize patching to mitigate risks.
Organizations should prioritize patching immediately to ensure the integrity and security of their systems.
Vulnerability Details
This vulnerability allows for out-of-bounds access, which could be exploited by a local user with elevated privileges. The official description states that this condition could lead to denial of service, arbitrary code execution, or information disclosure in System Management Mode.
The CVSS score of 8.1 signifies a high severity, indicating that the vulnerability poses a significant risk to organizations. Organizations should understand the implications of a local attack vector and the potential for high confidentiality and integrity impact.
The affected systems include various Dell PowerEdge Server BIOS versions, specifically those prior to the vendor patch which addresses this vulnerability.
Technical Analysis
The vulnerability arises from improper handling of array boundaries, which allows attackers to potentially access memory that they should not have access to. The attack vector is local, requiring high privileges to exploit, and the complexity of the attack is low, increasing the risk of exploitation.
Given that user interaction is not required, the vulnerability presents a significant risk to confidentiality and integrity, while availability impact is rated low. The vulnerability's scope is classified as 'changed', indicating that it can affect other components or systems.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-21557 is significant. Organizations utilizing affected Dell PowerEdge Server BIOS are potentially exposed to local attacks that could lead to severe operational disruptions. The blast radius is concerning, as the vulnerability affects multiple products and versions.
With the CVSS score indicating a high severity, organizations must assess their exposure to this vulnerability. Given that this vulnerability has not been included in the Known Exploited Vulnerabilities (KEV) catalog, it is essential to monitor for potential exploitation trends.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following Dell PowerEdge Server BIOS versions are affected: poweredge_r640_firmware, poweredge_r740_firmware, poweredge_r740xd_firmware, poweredge_r940_firmware, and several others as detailed in the official advisory. Organizations should consider all versions prior to vendor patch as vulnerable.
Mitigation & Remediation
To mitigate the risk posed by CVE-2021-21557, organizations should promptly apply the relevant patches provided by Dell. Upgrading to the latest firmware versions is crucial to close this vulnerability. Detailed patching instructions can be found on Dell's official support page.
If immediate patching is not possible, organizations should implement network controls to restrict access to systems at risk, along with monitoring for any suspicious activity.
For further information, organizations can refer to the guidance on penetration testing and remediation strategies.
Detection Guidance
Organizations should monitor logs for indicators of unauthorized access attempts or unusual system behavior that could signify exploitation of this vulnerability. Behavioral anomalies, such as unexpected system restarts or unauthorized BIOS changes, should be investigated promptly.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-21557 highlights the importance of regular firmware updates as part of an organization's security posture. This vulnerability is a reminder for security teams to maintain vigilance against local threats, especially in environments with elevated privileges.
Organizations are encouraged to evaluate their security practices and ensure they incorporate regular assessments, such as penetration testing methodology, to identify and remediate vulnerabilities proactively.
The patterns of exploitation in similar vulnerabilities underscore the need for continuous monitoring and proactive management of system configurations.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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