CVE-2017-11100 in SWFTools
Summary
by MITRE
When SWFTools 0.9.2 processes a crafted file in swfextract, it can lead to a NULL Pointer Dereference in the swf_FoldSprite() function in lib/rxfswf.c.
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Analysis
by VulDB Data Team • 12/12/2022
The vulnerability identified as CVE-2017-11100 represents a critical null pointer dereference flaw within SWFTools version 0.9.2, specifically affecting the swfextract utility when processing maliciously crafted input files. This issue resides in the lib/rxfswf.c source file within the swf_FoldSprite() function, where improper input validation leads to a scenario where a null pointer is dereferenced during the processing of malformed flash files. The vulnerability demonstrates a classic software security weakness that can be exploited to cause application crashes or potentially enable more sophisticated attack vectors.
The technical nature of this flaw stems from inadequate error handling and input validation mechanisms within the SWF processing library. When SWFTools encounters a specially crafted SWF file, the swf_FoldSprite() function fails to properly check for null pointer conditions before attempting to dereference memory locations. This type of vulnerability falls under CWE-476 which specifically addresses NULL Pointer Dereference issues in software implementations. The absence of proper null checks in the function's execution path creates a condition where the program attempts to access memory at address zero, resulting in immediate application termination or system instability.
From an operational perspective, this vulnerability poses significant risks to systems that process untrusted SWF content, particularly in environments where automated file analysis or content extraction services are deployed. Attackers could exploit this weakness by crafting malicious SWF files designed to trigger the null pointer dereference during swfextract execution, potentially leading to denial of service conditions that disrupt legitimate operations. The impact extends beyond simple application crashes, as such vulnerabilities often serve as entry points for more complex attack chains that could be leveraged for privilege escalation or information disclosure.
The exploitation of this vulnerability aligns with ATT&CK technique T1059.007 which covers the use of command-line interfaces and automated tools for executing malicious payloads. Systems utilizing SWFTools for automated content processing, file conversion, or security analysis may become vulnerable to targeted attacks that specifically craft SWF files to exploit this null pointer dereference. Organizations should consider implementing strict input validation protocols and sandboxing mechanisms to prevent the execution of untrusted SWF content through vulnerable tools. The recommended mitigation strategy involves updating to SWFTools versions that have patched this vulnerability, implementing network segmentation to isolate file processing systems, and deploying intrusion detection systems to monitor for suspicious SWF file processing activities that could indicate exploitation attempts.