CVE-2017-2821 in Perspective Document Filter
Summary
by MITRE
An exploitable use-after-free exists in the PDF parsing functionality of Lexmark Perspective Document Filters 11.3.0.2400 and 11.4.0.2452. A crafted PDF document can lead to a use-after-free resulting in direct code execution.
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Analysis
by VulDB Data Team • 12/27/2022
The vulnerability identified as CVE-2017-2821 represents a critical use-after-free flaw within the Lexmark Perspective Document Filters software suite, specifically affecting versions 11.3.0.2400 and 11.4.0.2452. This security weakness resides in the PDF parsing functionality that processes incoming document files, creating a pathway for remote code execution through carefully crafted malicious PDF content. The issue stems from improper memory management during the parsing process where freed memory locations are accessed after the original allocation has been released, creating a predictable exploitation vector for attackers. The vulnerability operates at the intersection of software security and memory safety, where the failure to properly manage object lifecycles in the document processing pipeline creates opportunities for arbitrary code execution. This type of vulnerability is particularly dangerous in print server environments where document filters process untrusted input from multiple sources, making the attack surface expansive and potentially affecting organizations with widespread print infrastructure deployments.
The technical implementation of this use-after-free vulnerability demonstrates a classic memory safety issue that can be categorized under CWE-416, which specifically addresses the use of freed memory conditions. When the Lexmark Perspective Document Filters encounters a malformed PDF document, the parsing engine allocates memory for PDF objects and subsequently frees this memory during the processing cycle. However, the application fails to properly invalidate references to these freed memory locations, allowing an attacker to manipulate the PDF structure to cause the application to access previously freed memory segments. The exploitation mechanism typically involves crafting a PDF file that triggers the memory allocation pattern, causes a premature deallocation, and then forces the application to execute code from the freed memory region. This process can be mapped to ATT&CK technique T1059.007, which describes the execution of malicious code through the manipulation of program execution flow. The vulnerability's exploitation requires precise control over memory layout and timing, making it suitable for advanced persistent threat actors who possess the capability to develop sophisticated payload delivery mechanisms.
The operational impact of CVE-2017-2821 extends beyond simple privilege escalation or denial of service scenarios, as it provides attackers with direct code execution capabilities within the context of the print processing environment. Organizations utilizing Lexmark Perspective Document Filters are particularly vulnerable since these systems often operate with elevated privileges to handle document processing tasks, potentially providing attackers with access to sensitive network resources or local system functionality. The vulnerability's remote exploitability means that attackers can compromise systems without requiring physical access, making it especially concerning for enterprise environments where print servers serve as central points of document handling across multiple departments and user groups. Network-based attacks can originate from external sources, potentially targeting the print infrastructure to gain unauthorized access to corporate networks, as print servers often maintain connections to internal systems and may be configured with administrative privileges. This vulnerability also represents a significant concern for organizations that rely heavily on print management solutions, as the attack surface includes not only the primary print servers but also any system components that interact with the document filtering functionality, potentially affecting entire print ecosystems.
Mitigation strategies for CVE-2017-2821 should encompass both immediate remediation and long-term security hardening measures. The most effective immediate solution involves applying the vendor-provided security patches or updates that address the memory management issues within the PDF parsing components. Organizations should also implement network segmentation and access controls to limit exposure of affected print servers to untrusted networks, reducing the potential attack vectors available to threat actors. Input validation and sanitization measures should be enhanced to filter out potentially malicious PDF content before it reaches the vulnerable parsing components, although this approach may not be fully effective against sophisticated attacks that can bypass simple content filtering. Security monitoring should be enhanced to detect anomalous behavior in print processing systems, including unexpected memory access patterns or unusual code execution sequences that could indicate exploitation attempts. Additionally, organizations should consider implementing application whitelisting policies that restrict which PDF processing applications can execute on print servers, reducing the potential impact of successful exploitation by limiting the attack surface. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing comprehensive security monitoring across all system components, particularly those that process untrusted input from external sources. Regular security assessments of document processing infrastructure should be conducted to identify and remediate similar memory safety issues that may exist in other components of the print ecosystem.