CVE-2016-9190 in Pillow
Summary
by MITRE
Pillow before 3.3.2 allows context-dependent attackers to execute arbitrary code by using the "crafted image file" approach, related to an "Insecure Sign Extension" issue affecting the ImagingNew in Storage.c component.
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Analysis
by VulDB Data Team • 09/29/2022
The vulnerability identified as CVE-2016-9190 represents a critical security flaw in the Pillow library, a popular Python imaging library used extensively for image processing tasks. This vulnerability stems from an insecure sign extension issue within the ImagingNew in Storage.c component, which creates a dangerous condition that can be exploited by context-dependent attackers to execute arbitrary code on affected systems. The flaw specifically affects Pillow versions prior to 3.3.2, making it a significant concern for organizations and developers who rely on this library for image handling operations. The vulnerability's classification as context-dependent means that exploitation requires specific conditions to be met, typically involving the processing of maliciously crafted image files that trigger the flawed code path.
The technical root cause of this vulnerability lies in how the ImagingNew function handles integer values during image processing operations, particularly when dealing with image dimensions and memory allocation. The insecure sign extension occurs when signed and unsigned integer values are improperly converted or compared, leading to unexpected behavior in memory management and buffer handling. This flaw allows attackers to manipulate image file headers or metadata in such a way that the library's internal calculations produce incorrect memory allocations or buffer boundaries. When the library processes these crafted image files, the improper sign extension causes memory corruption that can be leveraged to execute arbitrary code with the privileges of the process running the Pillow library.
The operational impact of CVE-2016-9190 extends beyond simple code execution, as it represents a potential vector for remote code execution in applications that process untrusted image content. This vulnerability affects web applications, image processing services, and any system that utilizes Pillow to handle user-uploaded or externally sourced image files. The attack scenario typically involves an attacker uploading a maliciously crafted image file that, when processed by the vulnerable Pillow library, triggers the insecure sign extension flaw. This could lead to complete system compromise, data exfiltration, or service disruption, particularly in environments where image processing is a core functionality. The vulnerability's impact is further amplified by the widespread adoption of Pillow across numerous Python applications and web frameworks, making it a prime target for automated exploitation attempts.
Organizations and developers should immediately upgrade to Pillow version 3.3.2 or later to address this vulnerability, as the fix includes proper handling of integer sign extension in the affected components. Additional mitigations include implementing strict input validation for image files, using sandboxed environments for image processing operations, and employing content filtering mechanisms to prevent the processing of untrusted image files. The vulnerability aligns with CWE-194, which describes "Unexpected Sign Extension" as a common pattern in integer overflow and underflow scenarios. From an ATT&CK framework perspective, this vulnerability maps to techniques involving code injection and privilege escalation, specifically targeting the execution of malicious code through library vulnerabilities. Regular security assessments and dependency updates should be implemented as part of security hygiene practices to prevent similar issues from affecting systems in production environments.