CVE-2021-31480 in Brava Desktop
Summary
by MITRE • 06/15/2021
This vulnerability allows remote attackers to execute arbitrary code on affected installations of OpenText Brava! Desktop 16.6.3.84. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of DXF files. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-12654.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/18/2021
The vulnerability identified as CVE-2021-31480 represents a critical security flaw in OpenText Brava! Desktop version 16.6.3.84, exposing systems to remote code execution attacks through improper handling of DXF file formats. This issue manifests as a type confusion vulnerability that occurs during the parsing of maliciously crafted DXF files, making it particularly dangerous for organizations that rely on document viewing and rendering capabilities. The vulnerability's exploitation requires user interaction, meaning that an attacker must convince a target to visit a malicious webpage or open a specially crafted file, which aligns with common social engineering attack vectors.
The technical root cause of this vulnerability lies in inadequate input validation mechanisms within the DXF file parser component of the Brava! Desktop application. When processing user-supplied DXF data, the software fails to properly validate the structure and content of the input, leading to a type confusion condition where the application incorrectly interprets data types during processing. This type confusion allows an attacker to manipulate memory layout and potentially overwrite critical program variables or function pointers. The vulnerability operates at the application level, where the parsing logic does not adequately distinguish between different data types, creating opportunities for attackers to inject malicious code that executes within the context of the currently running process with the same privileges as the legitimate user.
From an operational impact perspective, this vulnerability poses significant risks to enterprise environments that utilize OpenText Brava! Desktop for document viewing and collaboration. The requirement for user interaction reduces the attack surface compared to fully automated exploits, but it does not eliminate the threat entirely. Organizations with high volumes of document sharing and collaboration are particularly vulnerable, as users may inadvertently encounter malicious DXF files through email attachments, file sharing platforms, or web-based document repositories. The successful exploitation of this vulnerability could result in complete system compromise, data exfiltration, and potential lateral movement within the network. According to CWE classification, this vulnerability maps to CWE-415: Double Free and CWE-471: Modification of Externally-Controllable Resource, reflecting the memory management and input validation failures present in the affected software. The attack pattern aligns with ATT&CK techniques including T1059.001: Command and Scripting Interpreter and T1203: Exploitation for Client Execution, demonstrating how attackers can leverage file format vulnerabilities to establish persistent access.
The remediation approach for this vulnerability requires immediate patching of the OpenText Brava! Desktop application to the latest version that addresses the DXF parsing logic and implements proper input validation mechanisms. Organizations should also implement network-based controls such as web application firewalls and content filtering solutions to block suspicious file downloads and prevent users from accessing potentially malicious content. Additionally, user education and awareness programs should emphasize the importance of verifying document sources before opening files, particularly those received via email or downloaded from untrusted sources. System administrators should consider implementing application whitelisting policies to restrict execution of unauthorized file formats and monitor for unusual file access patterns. The vulnerability's classification as a type confusion issue underscores the importance of regular security assessments and code reviews focusing on memory management practices, particularly in applications that handle external file formats. Organizations should also consider deploying sandboxing solutions to isolate document processing activities and prevent successful exploitation attempts from compromising the broader system environment.