CVE-2021-40385 in Unitrends Backup Software
Summary
by MITRE • 09/02/2021
An issue was discovered in the server software in Kaseya Unitrends Backup Software before 10.5.5-2. There is a privilege escalation from read-only user to admin.
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Analysis
by VulDB Data Team • 09/04/2021
The vulnerability identified as CVE-2021-40385 represents a critical privilege escalation flaw within Kaseya Unitrends Backup Software versions prior to 10.5.5-2. This security weakness allows an attacker with read-only user privileges to escalate their access level to administrative rights, fundamentally compromising the software's security model. The issue stems from inadequate access control mechanisms that fail to properly validate user permissions during critical operations, creating an avenue for unauthorized privilege elevation.
The technical implementation of this vulnerability demonstrates a classic improper access control scenario that aligns with CWE-285, which addresses improper authorization within software systems. The flaw likely exists in the server-side processing logic where read-only users can manipulate specific API endpoints or internal functions that should be restricted to administrators only. This type of vulnerability typically arises from insufficient input validation, missing permission checks, or flawed privilege verification mechanisms within the application's authentication and authorization framework.
From an operational impact perspective, this privilege escalation vulnerability poses severe risks to organizations relying on Kaseya Unitrends Backup Software for their data protection infrastructure. An attacker who gains initial access through a read-only user account can subsequently access sensitive backup data, modify backup configurations, manipulate recovery processes, and potentially exfiltrate critical information. The implications extend beyond simple unauthorized access as administrators possess the ability to modify system settings, create new user accounts, and access all backup repositories that may contain confidential organizational data.
The attack vector for this vulnerability typically involves exploiting misconfigured access controls through API calls or web interface interactions that should normally be restricted to privileged users. Security frameworks such as MITRE ATT&CK categorize this type of weakness under privilege escalation techniques, specifically targeting the 'Valid Accounts' and 'Exploitation for Privilege Escalation' tactics. The vulnerability's exploitation requires minimal initial access but can result in maximum impact, making it particularly dangerous in enterprise environments where backup systems often contain comprehensive organizational data.
Organizations should immediately implement the vendor-provided patch for Kaseya Unitrends Backup Software version 10.5.5-2 to remediate this vulnerability. Additionally, network segmentation should be implemented to limit access to backup systems, and regular privilege reviews should be conducted to ensure least privilege principles are maintained. Security monitoring should be enhanced to detect unusual access patterns and privilege escalation attempts within the backup infrastructure. The remediation process should include comprehensive testing to ensure the patch does not introduce compatibility issues with existing backup operations while maintaining the integrity of the backup environment's security posture.