CVE-2018-12933 in Wine
Summary
by MITRE
PlayEnhMetaFileRecord in enhmetafile.c in Wine 3.7 allows attackers to cause a denial of service (out-of-bounds write) or possibly have unspecified other impact because the attacker controls the pCreatePen->ihPen array index.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-12933 resides within the Wine compatibility layer implementation, specifically in the PlayEnhMetaFileRecord function located in the enhmetafile.c source file. This flaw affects Wine version 3.7 and represents a critical security issue that demonstrates how improper input validation can lead to severe system instability. The vulnerability manifests when processing enhanced metafile records, which are used to store graphical operations in Windows-compatible applications running under Wine. The core issue stems from insufficient bounds checking on array indexing operations, creating a potential attack surface that could be exploited by malicious actors.
The technical flaw involves an out-of-bounds write condition that occurs when the attacker controls the pCreatePen->ihPen array index value. This particular vulnerability maps to CWE-787, which describes out-of-bounds write conditions in software implementations. The flaw exists because the PlayEnhMetaFileRecord function fails to validate the range of the ihPen array index before using it to access memory locations. When an attacker crafts a specially formatted enhanced metafile record with malicious ihPen values, the application can write data beyond the allocated memory boundaries of the pCreatePen->ihPen array. This memory corruption can result in unpredictable behavior including application crashes, denial of service conditions, or potentially more severe consequences depending on the execution context.
From an operational impact perspective, this vulnerability creates significant risks for systems running Wine applications, particularly those that process untrusted graphical content from external sources. The denial of service aspect means that legitimate users could experience application instability or complete system crashes when encountering malicious metafile records. The unspecified other impacts mentioned in the description suggest that under certain conditions, this vulnerability could potentially be escalated to achieve arbitrary code execution or privilege escalation, though this would depend heavily on the specific execution environment and memory layout. The vulnerability affects the broader Windows compatibility layer ecosystem, as Wine serves as a bridge for many Windows applications to run on Unix-like systems, making it a critical point of concern for system administrators and security professionals managing cross-platform environments.
The attack surface for this vulnerability is primarily limited to applications that process enhanced metafile records through Wine's graphics subsystem, which includes many Windows applications that utilize graphical operations and drawing capabilities. The ATT&CK framework would categorize this as a memory corruption technique under the system binary modification or privilege escalation tactics, depending on the specific exploitation method. Mitigation strategies should include immediate patching of Wine to version 3.8 or later where the vulnerability has been addressed through proper bounds checking and input validation. System administrators should also implement strict input validation for any graphical content processed through Wine, particularly when dealing with untrusted sources. Additionally, organizations should consider isolating Wine-based applications in sandboxed environments to limit the potential impact of successful exploitation attempts. The fix implemented in Wine 3.8 demonstrates the importance of proper array bounds checking and input validation in preventing memory corruption vulnerabilities that could lead to system instability or more serious security breaches.