CVE-2018-12648 in Exempi
Summary
by MITRE
The WEBP::GetLE32 function in XMPFiles/source/FormatSupport/WEBP_Support.hpp in Exempi 2.4.5 has a NULL pointer dereference.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-12648 represents a critical null pointer dereference flaw within the Exempi library version 2.4.5, specifically affecting the WEBP::GetLE32 function located in XMPFiles/source/FormatSupport/WEBP_Support.hpp. This issue arises during the processing of webp image files when the library attempts to parse metadata contained within these files. The flaw occurs when the function receives malformed or improperly structured webp file data that results in a null pointer being dereferenced during the extraction of little-endian 32-bit values from the file's metadata structure. Such a condition can lead to application crashes or potentially more severe consequences depending on how the library is integrated into larger software systems.
The technical implementation of this vulnerability stems from inadequate input validation within the WEBP_Support.hpp file where the WEBP::GetLE32 function fails to properly check for null pointer conditions before attempting to access memory locations. This type of flaw falls under the common weakness enumeration CWE-476 which specifically addresses NULL pointer dereference vulnerabilities. When an attacker crafts a malicious webp file with malformed metadata structures, the library's parsing routine will attempt to read from a null pointer location, causing the application to terminate unexpectedly. The vulnerability is particularly concerning because it can be exploited through file-based attacks where an application using Exempi for metadata processing opens or processes a specially crafted webp file.
The operational impact of this vulnerability extends beyond simple application crashes, as it can be leveraged in various attack scenarios including denial of service attacks against applications that utilize Exempi for image metadata handling. Systems that process webp files from untrusted sources such as web applications, content management systems, or digital asset management platforms become vulnerable to exploitation. The ATT&CK framework categorizes this type of vulnerability under T1203 - Exploitation for Client Execution when it can be used to cause applications to crash or behave unpredictably, potentially leading to service disruption. Additionally, this vulnerability could be chained with other exploits if the application fails to properly handle the crash or if the library is used in a context where such failures could be leveraged for further compromise.
Mitigation strategies for CVE-2018-12648 should focus on immediate patching of the Exempi library to version 2.4.6 or later where the null pointer dereference has been addressed. Organizations should implement comprehensive input validation measures when processing webp files, including thorough file format checking and sanitization routines before passing files to the Exempi library. Network-based defenses can include content filtering solutions that scan for and block suspicious webp files, while application-level protections should incorporate proper error handling and exception management to prevent crashes from propagating. The fix typically involves adding null pointer checks before memory access operations in the WEBP::GetLE32 function, ensuring that all pointers are validated before dereferencing. Security monitoring should also be enhanced to detect unusual application behavior patterns that might indicate exploitation attempts, particularly in systems where Exempi is integrated for automated image processing tasks.