CVE-2017-11097 in SWFTools
Summary
by MITRE
When SWFTools 0.9.2 processes a crafted file in swfc, it can lead to a NULL Pointer Dereference in the dict_lookup() function in lib/q.c.
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Analysis
by VulDB Data Team • 12/12/2022
The vulnerability identified as CVE-2017-11097 represents a critical NULL pointer dereference flaw within SWFTools version 0.9.2, specifically affecting the swfc compiler component. This issue manifests when the software processes maliciously crafted input files, creating a scenario where the dict_lookup() function in lib/q.c attempts to dereference a null pointer, leading to potential application crashes or system instability. The vulnerability stems from inadequate input validation and error handling mechanisms within the SWF file processing pipeline, particularly in how the software manages dictionary lookups during compilation operations. This flaw exists in the core processing logic of SWFTools, which is widely used for converting and manipulating flash content, making it a significant concern for organizations relying on this toolchain for media processing and conversion tasks.
The technical exploitation of this vulnerability occurs when an attacker crafts a specially formatted SWF file that triggers the dict_lookup() function to operate on a null dictionary entry. This function, located in the lib/q.c source file, fails to properly validate whether the dictionary pointer is valid before attempting to access its contents. The CWE-476 identifier applies here as this represents a NULL pointer dereference vulnerability, where the software does not properly check for null values before dereferencing pointers during dictionary operations. When the swfc utility processes such malformed input, the execution flow leads to a segmentation fault or access violation, causing the application to terminate unexpectedly. The flaw is particularly dangerous because it can be triggered through normal file processing operations, requiring no special privileges or complex attack vectors beyond crafting the malicious input file.
The operational impact of CVE-2017-11097 extends beyond simple application crashes, as it can be leveraged for denial of service attacks against systems that rely on SWFTools for content processing. Attackers can exploit this vulnerability by submitting crafted SWF files to systems running vulnerable versions of SWFTools, potentially causing service disruption for legitimate users. This vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, as the exploitation can effectively render systems unusable by causing repeated crashes during file processing operations. The vulnerability affects not only individual user systems but also enterprise environments where SWFTools might be integrated into automated workflows, content management systems, or web applications that process user-uploaded flash content. Organizations using this tool for legitimate purposes face increased risk of operational disruption, particularly in environments where automated processing pipelines depend on SWFTools functionality.
Mitigation strategies for CVE-2017-11097 should prioritize immediate software updates to versions that address the NULL pointer dereference issue in the dict_lookup() function. System administrators should implement input validation measures to filter potentially malicious SWF files before processing, particularly in automated environments where untrusted content is accepted. The implementation of sandboxing techniques around SWFTools execution can provide additional protection by isolating vulnerable processes from critical system resources. Organizations should also consider implementing network-level controls to prevent the upload or distribution of potentially malicious SWF content, especially in web applications that process user-generated media. Regular security assessments of SWFTools installations and monitoring for abnormal application behavior can help detect exploitation attempts. The vulnerability highlights the importance of proper error handling and input validation in security-critical applications, as recommended by industry standards including the OWASP Top Ten and NIST cybersecurity guidelines for secure software development practices.