CVE-2018-19149 in Poppler
Summary
by MITRE
Poppler before 0.70.0 has a NULL pointer dereference in _poppler_attachment_new when called from poppler_annot_file_attachment_get_attachment.
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Analysis
by VulDB Data Team • 06/05/2023
The vulnerability identified as CVE-2018-19149 represents a critical NULL pointer dereference flaw within the Poppler PDF rendering library version 0.70.0 and earlier. This vulnerability specifically manifests in the _poppler_attachment_new function when invoked through the poppler_annot_file_attachment_get_attachment API call. The flaw occurs when the library attempts to process malformed or specially crafted PDF attachments without proper validation of attachment pointers, leading to a potential system crash or denial of service condition. The issue stems from insufficient input sanitization and error handling within the attachment processing subsystem of the PDF parser.
The technical implementation of this vulnerability involves a classic null pointer dereference scenario where the _poppler_attachment_new function fails to validate whether the attachment parameter is properly initialized before attempting to access its members. When poppler_annot_file_attachment_get_attachment is called with a malformed PDF file containing crafted attachment data, the function passes a NULL pointer to _poppler_attachment_new which then attempts to dereference this null reference, causing an immediate system crash. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations. The vulnerability is particularly concerning because it can be triggered through normal PDF file processing operations without requiring special privileges or complex exploitation techniques.
From an operational impact perspective, this vulnerability creates significant risks for systems that process untrusted PDF documents, including web browsers, email clients, document management systems, and any application that utilizes Poppler for PDF rendering. The denial of service aspect means that attackers can potentially crash applications by simply providing a maliciously crafted PDF file, leading to service disruption and potential system instability. In environments where PDF processing is automated or occurs in high-volume scenarios, this vulnerability could be exploited to create sustained denial of service conditions. The vulnerability also presents potential security implications beyond simple denial of service, as it may serve as a stepping stone for more complex exploitation techniques or could be combined with other vulnerabilities to achieve arbitrary code execution in vulnerable applications.
The recommended mitigation strategies for CVE-2018-19149 involve immediate upgrading to Poppler version 0.70.0 or later where the vulnerability has been patched. Organizations should also implement proper input validation and sanitization measures for PDF files before processing them through any Poppler-based applications. Additionally, deploying network-based intrusion detection systems that can identify and block suspicious PDF file patterns may provide an additional layer of protection. The fix implemented in version 0.70.0 addresses the core issue by adding proper null pointer checks and validation within the attachment processing functions, aligning with best practices for secure coding and defensive programming. This vulnerability demonstrates the importance of proper error handling and input validation in security-critical libraries and aligns with ATT&CK technique T1203 which covers the exploitation of input validation vulnerabilities to achieve system compromise or denial of service conditions.