CVE-2021-26473 in BDR Suite
Summary
by MITRE • 06/09/2021
Vembu BDR Suite before 4.2.0 allows Unauthenticated file write via a GET request that specifies a file's name and content.
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Analysis
by VulDB Data Team • 06/11/2021
The vulnerability identified as CVE-2021-26473 affects Vembu BDR Suite versions prior to 4.2.0 and represents a critical security flaw that enables unauthenticated remote attackers to perform arbitrary file write operations. This vulnerability exists within the web application interface of the backup and disaster recovery solution, which is commonly deployed in enterprise environments for data protection and recovery purposes. The flaw stems from insufficient input validation and authentication mechanisms within the application's file handling functionality, creating a pathway for malicious actors to inject and write files to the target system without requiring valid credentials or authorization.
The technical implementation of this vulnerability allows attackers to exploit a GET request parameter that specifies both the filename and content to be written to the server. This type of vulnerability falls under the category of insecure direct object references and improper access control as classified by CWE-22 and CWE-285. The flaw specifically manifests when the application processes user-supplied file names and content through a GET request without adequate sanitization or authentication checks. Attackers can leverage this vulnerability to upload malicious files including web shells, configuration files, or other harmful content that could compromise the entire backup infrastructure.
The operational impact of CVE-2021-26473 is severe and multifaceted, particularly given that Vembu BDR Suite is designed for enterprise backup and disaster recovery operations. An attacker who successfully exploits this vulnerability gains the ability to write arbitrary files to the system, potentially leading to complete system compromise, data exfiltration, or disruption of backup operations. The unauthenticated nature of the attack means that any remote user can exploit this flaw without requiring prior access credentials, making it especially dangerous in environments where the backup infrastructure is exposed to untrusted networks. This vulnerability directly aligns with tactics described in the MITRE ATT&CK framework under T1190 (Exploit Public-Facing Application) and T1059 (Command and Scripting Interpreter) as attackers can leverage the file upload capability to establish persistent access or execute malicious code.
Organizations utilizing Vembu BDR Suite versions prior to 4.2.0 should immediately implement mitigations to protect their backup infrastructure from exploitation. The primary recommended action is to upgrade to version 4.2.0 or later, which includes proper authentication checks and input validation mechanisms that prevent unauthorized file write operations. Additionally, network segmentation should be implemented to limit access to the backup server, and firewall rules should be configured to restrict access to the vulnerable web interface from untrusted networks. Security monitoring should be enhanced to detect unusual file creation patterns or suspicious GET requests targeting the backup application. The vulnerability demonstrates the critical importance of proper authentication and input validation in web applications, particularly in systems handling sensitive backup data that could be leveraged for lateral movement or persistent access within an organization's network infrastructure.