CVE-2020-29495 in Avamar Server
Summary
by MITRE • 01/15/2021
DELL EMC Avamar Server, versions 19.1, 19.2, 19.3, contain an OS Command Injection Vulnerability in Fitness Analyzer. A remote unauthenticated attacker could potentially exploit this vulnerability, leading to the execution of arbitrary OS commands on the application's underlying OS with high privileges. This vulnerability is considered critical as it can be leveraged to completely compromise the vulnerable application as well as the underlying operating system. Dell recommends customers to upgrade at the earliest opportunity.
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Analysis
by VulDB Data Team • 02/14/2021
The CVE-2020-29495 vulnerability represents a critical operating system command injection flaw within Dell EMC Avamar Server versions 19.1 through 19.3, specifically affecting the Fitness Analyzer component. This vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing within the system's command execution pathways. The flaw exists in the application's handling of parameters that are subsequently passed to underlying operating system commands, creating an avenue for malicious input to be interpreted and executed as legitimate system commands rather than mere data.
The technical exploitation of this vulnerability occurs through a remote unauthenticated attack vector, meaning that adversaries do not require valid credentials or network access to the system to leverage the flaw. This makes the vulnerability particularly dangerous as it can be exploited from anywhere on the internet without prior authorization or authentication. The Fitness Analyzer component, which is designed to assess system health and performance metrics, inadvertently processes user input through shell command execution contexts where proper sanitization fails to occur. This allows attackers to inject malicious commands that execute with the highest privileges available to the application, typically corresponding to the root or administrator level permissions of the underlying operating system.
The operational impact of this vulnerability extends far beyond simple data compromise, as successful exploitation provides complete system compromise capabilities. Attackers can leverage this vulnerability to execute arbitrary code with elevated privileges, potentially leading to full system takeover, data exfiltration, lateral movement within network environments, and persistent backdoor establishment. The high privilege execution context means that compromised systems can be used as launching points for further attacks against network infrastructure, potentially affecting other connected systems and services. Organizations relying on Dell EMC Avamar for backup and recovery operations face particularly severe consequences, as compromising the Avamar server can lead to complete disruption of backup operations and potential data loss.
Security professionals should note that this vulnerability aligns with CWE-77 and CWE-88 categories from the Common Weakness Enumeration, specifically addressing command injection weaknesses where external input is improperly incorporated into command execution contexts. The ATT&CK framework would categorize this vulnerability under T1059.001 for command and script interpreter execution, with potential lateral movement capabilities through T1021.002 for remote services and T1078.004 for valid accounts. Organizations should prioritize immediate remediation through the recommended Dell EMC software updates and patches, while implementing network segmentation and monitoring to detect potential exploitation attempts. Additionally, implementing input validation controls and privilege separation measures can provide additional defense-in-depth protections against similar vulnerabilities in the future.