CVE-2014-0994 in C++Builder
Summary
by MITRE
Heap-based buffer overflow in the ReadDIB function in the Vcl.Graphics.TPicture.Bitmap implementation in the Visual Component Library (VCL) in Embarcadero Delphi XE6 20.0.15596.9843 and C++ Builder XE6 20.0.15596.9843 allows context-dependent attackers to execute arbitrary code via the BITMAPINFOHEADER.biClrUsed field in a BMP file. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-0993.
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Analysis
by VulDB Data Team • 02/16/2022
The vulnerability described in CVE-2014-0994 represents a critical heap-based buffer overflow within the Visual Component Library's bitmap handling functionality of Embarcadero Delphi XE6 and C++ Builder XE6. This flaw specifically affects the ReadDIB function within the Vcl.Graphics.TPicture.Bitmap implementation, which is responsible for processing bitmap image files. The vulnerability manifests when processing BITMAPINFOHEADER.biClrUsed field values in BMP files, creating an exploitable condition that allows remote attackers to execute arbitrary code within the context of the application's process. The issue stems from an incomplete remediation of a previously identified vulnerability, CVE-2014-0993, which demonstrates a pattern of security regression where fixes fail to address all potential attack vectors within the same codebase.
The technical implementation of this vulnerability involves improper bounds checking during the parsing of bitmap file headers, specifically when the biClrUsed field contains maliciously crafted values that exceed the allocated buffer boundaries. This field in the BITMAPINFOHEADER structure is designed to specify the number of color indices in the color table that are actually used by the bitmap, but the vulnerable implementation fails to validate this value against the actual buffer size allocated for color table processing. When an attacker supplies a value that appears legitimate to the parser but exceeds the allocated memory space, the subsequent memory operations overflow into adjacent heap memory regions, potentially allowing for memory corruption that can be exploited to gain control over the executing process. This type of vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a classic example of insufficient input validation in binary file processing components.
The operational impact of CVE-2014-0994 extends beyond simple code execution, as it enables attackers to leverage the vulnerability through various attack vectors including malicious email attachments, web downloads, or file sharing scenarios where users might inadvertently open compromised bitmap files. The context-dependent nature of this vulnerability means that exploitation typically requires the target application to actively process the malicious bitmap file, making it particularly dangerous in applications that handle untrusted image data from external sources. Attackers can potentially leverage this vulnerability to perform privilege escalation, data theft, or system compromise, especially when the vulnerable application runs with elevated privileges. The vulnerability's presence in widely used development environments like Delphi XE6 and C++ Builder XE6 makes it particularly concerning as it affects numerous applications that process bitmap images, creating a broad attack surface that can be exploited across multiple software implementations.
Security mitigations for this vulnerability should focus on immediate patching of affected versions, as the vendor has released updates to address the heap overflow condition. Organizations should implement strict input validation measures for all bitmap file processing, including parameter validation of the biClrUsed field and comprehensive bounds checking before any memory allocation occurs. Network-based defenses should include file type filtering and content inspection to prevent malicious bitmap files from reaching vulnerable applications. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1203 (Exploitation for Client Execution) where the execution of arbitrary code represents a direct path to system compromise. Additionally, implementing application whitelisting and sandboxing measures can provide defense-in-depth protection against exploitation attempts, while regular security assessments of third-party components can help identify similar incomplete fixes that may exist in other parts of the application stack.