CVE-2021-34893 in View
Summary
by MITRE • 01/14/2022
This vulnerability allows remote attackers to execute arbitrary code on affected installations of Bentley View 10.15.0.75. 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 BMP files. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-14846.
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Analysis
by VulDB Data Team • 01/17/2022
The vulnerability identified as CVE-2021-34893 represents a critical buffer overflow flaw in Bentley View version 10.15.0.75 that enables remote code execution through malicious BMP file manipulation. This issue falls under the CWE-121 buffer overflow category, specifically manifesting as a heap-based buffer overflow during the parsing of bitmap image files. The vulnerability stems from insufficient input validation mechanisms within the software's image processing pipeline, where user-supplied data is copied to heap-allocated buffers without proper length verification. Attackers can exploit this weakness by crafting malicious BMP files that contain oversized or malformed data structures, causing the application to copy more data than the allocated buffer can accommodate.
The exploitation of this vulnerability requires user interaction, making it a client-side attack vector that typically involves social engineering tactics to lure victims into opening malicious files or visiting compromised websites. When a user attempts to view a crafted BMP file within Bentley View, the application's insufficient bounds checking allows the attacker-controlled data to overwrite adjacent memory locations, potentially leading to arbitrary code execution with the privileges of the running process. This particular flaw demonstrates the classic characteristics of a stack-based buffer overflow that has been adapted for heap memory corruption, where the attacker can manipulate the program's execution flow by overwriting return addresses or function pointers stored in memory.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable attackers to establish persistent access to affected systems and potentially escalate privileges within the application's security context. The vulnerability affects organizations that rely on Bentley View for engineering and architectural document review, making it particularly concerning for construction companies, engineering firms, and government agencies that handle sensitive project documentation. Security professionals should note that this vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could allow attackers to execute malicious commands within the application's runtime environment. The heap-based nature of the buffer overflow also makes this vulnerability suitable for advanced exploitation techniques including heap spraying and return-oriented programming attacks.
Organizations should implement immediate mitigations including updating to the latest version of Bentley View that contains patches for this vulnerability, disabling BMP file handling capabilities when not required, and implementing network-based restrictions to prevent access to potentially malicious content. Additionally, security teams should deploy application whitelisting policies to restrict execution of unauthorized software and monitor for unusual file access patterns that might indicate exploitation attempts. The vulnerability's classification as a heap-based buffer overflow underscores the importance of memory safety practices in software development and highlights the need for comprehensive input validation mechanisms that align with industry standards such as those recommended by the CERT/CC and the Open Web Application Security Project. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other image processing components within the organization's software ecosystem.