CVE-2017-2579 in netpbm
Summary
by MITRE
An out-of-bounds read vulnerability was found in netpbm before 10.61. The expandCodeOntoStack() function has an insufficient code value check, so that a maliciously crafted file could cause the application to crash or possibly allows code execution.
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Analysis
by VulDB Data Team • 03/10/2020
The vulnerability identified as CVE-2017-2579 represents a critical out-of-bounds read flaw within the netpbm image processing library version 10.61 and earlier. This issue manifests in the expandCodeOntoStack() function where inadequate validation of code values creates a pathway for exploitation. The netpbm library serves as a foundational component for processing various image formats including ppm, pgm, and pbm files, making this vulnerability particularly concerning given the widespread use of these formats in both commercial and open source applications. The flaw stems from insufficient bounds checking during the parsing of image data structures, specifically when handling compressed or encoded data sequences that are processed through the stack-based expansion mechanism.
The technical implementation of this vulnerability allows an attacker to craft specially formatted image files that trigger memory access violations when the expandCodeOntoStack() function attempts to process invalid code values. This function operates by expanding compressed code sequences onto a stack structure, but fails to validate the range of code values before performing stack operations. When malformed input data containing out-of-bounds code values is processed, the function can access memory locations beyond the allocated stack boundaries, leading to unpredictable behavior including application crashes, memory corruption, or potential code execution. This type of vulnerability aligns with CWE-129, which specifically addresses insufficient validation of length of input buffers, and represents a classic example of buffer over-read conditions that can be exploited through crafted input files.
The operational impact of CVE-2017-2579 extends beyond simple application instability to potentially enable remote code execution in scenarios where netpbm is used in server-side processing environments or when integrated into larger applications that process untrusted image data. Systems utilizing netpbm for automated image processing, web applications handling user-uploaded images, or content management systems that rely on this library for image manipulation become vulnerable to exploitation. The vulnerability can be leveraged through the ATT&CK technique of "Command and Scripting Interpreter" when combined with file upload capabilities, or through "Exploitation for Client Execution" when targeting applications that process image files from untrusted sources. The exploitability is particularly high in environments where netpbm is used in web applications or automated processing pipelines, as attackers can simply upload a maliciously crafted image file to trigger the vulnerability.
Mitigation strategies for this vulnerability require immediate patching of netpbm installations to version 10.61 or later, where the insufficient code value checks have been addressed. Organizations should implement input validation measures that enforce strict bounds checking on all image data processed through the library, particularly focusing on code value ranges within the expandCodeOntoStack() function. Additionally, deployment of network-based intrusion detection systems should include signature detection for malformed image file patterns that could indicate exploitation attempts. The vulnerability demonstrates the importance of thorough input validation in image processing libraries and highlights the need for proper bounds checking in stack-based data expansion algorithms. Security teams should also consider implementing sandboxing mechanisms for image processing operations and conducting regular vulnerability assessments of third-party libraries to identify similar issues that may exist in other image processing components.