CVE-2005-1142 in Optical Character Recognition Utility
Summary
by MITRE
Heap-based buffer overflow in the readpgm function in pnm.c for GOCR 0.40, when it is not using netpbm, allows remote attackers to execute arbitrary code via a P3 format PNM file with more data than implied by its width and height values.
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Analysis
by VulDB Data Team • 07/22/2017
The vulnerability described in CVE-2005-1142 represents a critical heap-based buffer overflow affecting GOCR version 0.40, specifically within the readpgm function located in pnm.c. This flaw occurs when the application processes P3 format PNM files without utilizing the netpbm library, creating a dangerous condition where attacker-controlled data can overwrite adjacent memory regions. The vulnerability stems from inadequate input validation and bounds checking during the parsing of PNM image files, which are commonly used for storing portable pixmap images. When a maliciously crafted P3 file is processed, the application fails to properly verify that the amount of data read matches the dimensions specified in the file header, leading to memory corruption that can be exploited to execute arbitrary code.
The technical implementation of this vulnerability involves the manipulation of PNM file structure where the width and height parameters in the P3 format header are deliberately set to values that contradict the actual data content. The readpgm function in GOCR fails to perform proper bounds checking on the data stream, allowing the program to write more bytes into allocated heap memory than originally intended. This heap overflow creates a condition where the overflowed memory can overwrite adjacent heap chunks, potentially corrupting pointers, function return addresses, or other critical program data structures. The vulnerability is particularly dangerous because it allows remote code execution, meaning an attacker can craft a malicious P3 file and deliver it via network channels such as email attachments, web downloads, or file sharing systems without requiring local system access.
From an operational perspective, this vulnerability poses significant risks to systems running GOCR version 0.40, especially in environments where document processing or optical character recognition services are exposed to untrusted input. The attack vector requires only that a user or application process a malicious P3 file, making it particularly dangerous in automated processing environments or web applications that accept image uploads. The exploitation of this vulnerability can lead to complete system compromise, allowing attackers to gain arbitrary code execution privileges, potentially escalating to full system control. Organizations using GOCR for document processing, OCR services, or automated image analysis systems are particularly vulnerable, as these applications often process untrusted user input without proper sanitization. The vulnerability also impacts systems where GOCR is used as part of larger document management or content processing workflows, where a single compromised file could affect entire processing pipelines.
The remediation strategy for this vulnerability requires immediate patching of GOCR to version 0.41 or later, which includes proper bounds checking and input validation for PNM file processing. Organizations should implement comprehensive input validation measures that verify file dimensions match actual data content before processing, and employ memory safety techniques such as stack canaries, address space layout randomization, and heap integrity checks. The vulnerability aligns with CWE-121, heap-based buffer overflow, and maps to ATT&CK technique T1059.007 for remote code execution through malicious file processing. System administrators should also implement network segmentation and file type restrictions to prevent automatic processing of untrusted PNM files, while monitoring for suspicious file processing activities. Regular security assessments of document processing systems and OCR applications should include verification of input validation controls and memory safety mechanisms to prevent similar vulnerabilities from being exploited in other components of the processing pipeline.