CVE-2017-18237 in Exempi
Summary
by MITRE
An issue was discovered in Exempi before 2.4.3. The PostScript_Support::ConvertToDate function in XMPFiles/source/FormatSupport/PostScript_Support.cpp allows remote attackers to cause a denial of service (invalid pointer dereference and application crash) via a crafted .ps file.
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Analysis
by VulDB Data Team • 02/22/2023
The vulnerability identified as CVE-2017-18237 represents a critical denial of service flaw within the Exempi library, a component widely used for handling XMP metadata in various applications. This library serves as a foundational element in numerous software products including Adobe Creative Suite, various digital asset management systems, and multimedia processing tools that rely on proper metadata handling. The issue specifically resides in the PostScript_Support::ConvertToDate function located within the XMPFiles/source/FormatSupport/PostScript_Support.cpp source file, where the software fails to properly validate input data before processing. The vulnerability manifests when the library encounters a specially crafted .ps file that contains malformed date information, leading to a scenario where the application attempts to dereference an invalid memory pointer during the conversion process.
The technical exploitation of this vulnerability occurs through a carefully constructed PostScript file that triggers an invalid pointer dereference within the ConvertToDate function. When an application utilizing Exempi processes such a malicious file, the function attempts to access memory locations that have not been properly initialized or have already been freed, resulting in an application crash. This behavior aligns with CWE-476, which describes NULL pointer dereference conditions that can lead to system instability and denial of service. The flaw demonstrates characteristics of a classic buffer over-read scenario where the application's memory management fails to properly validate the boundaries of expected data structures, particularly when parsing date formats within PostScript content.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Exempi-based applications, as it can be exploited by remote attackers to disrupt services without requiring authentication or specialized privileges. The impact extends beyond simple application crashes to potentially affect entire content management workflows, digital asset pipelines, and multimedia processing systems that depend on stable metadata handling. Attackers can leverage this vulnerability by simply providing a malicious .ps file to any application that processes such files through the affected Exempi library, making it particularly dangerous in environments where automated processing of user-uploaded content occurs. The vulnerability's remote exploitability means that it can be triggered through web-based interfaces, email attachments, or any other vector that allows the delivery of malicious PostScript files to vulnerable systems.
The mitigation strategy for CVE-2017-18237 requires immediate patching of all affected systems to upgrade to Exempi version 2.4.3 or later, which contains the necessary code fixes to properly validate date format inputs before attempting conversion operations. Organizations should also implement input validation measures at network boundaries to filter out potentially malicious PostScript files, particularly in environments where untrusted content processing occurs. System administrators should conduct comprehensive vulnerability assessments to identify all applications that utilize the affected Exempi library and ensure proper patch management protocols are in place. This vulnerability also highlights the importance of proper memory management practices and input validation in security-critical libraries, aligning with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion and invalid input processing. Additionally, implementing proper error handling and exception management within applications that utilize Exempi can provide additional defense-in-depth measures to prevent crash scenarios from occurring in production environments.