CVE-2015-9261 in BusyBox
Summary
by MITRE
huft_build in archival/libarchive/decompress_gunzip.c in BusyBox before 1.27.2 misuses a pointer, causing segfaults and an application crash during an unzip operation on a specially crafted ZIP file.
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Analysis
by VulDB Data Team • 04/25/2023
The vulnerability identified as CVE-2015-9261 represents a critical memory management flaw within the BusyBox archive decompression functionality, specifically affecting the gunzip decompression component. This issue manifests in the huft_build function located within archival/libarchive/decompress_gunzip.c, where improper pointer handling leads to severe system instability. The vulnerability affects BusyBox versions prior to 1.27.2, making it a widespread concern across numerous embedded systems and Linux environments that rely on this ubiquitous utility. The flaw operates through a classic buffer over-read condition that occurs during the decompression of specially crafted zip files, where the application fails to properly validate pointer arithmetic during Huffman tree construction. This mismanagement creates a scenario where the decompression process attempts to access memory locations beyond the allocated buffer boundaries, resulting in segmentation faults and complete application termination.
The technical exploitation of this vulnerability requires an attacker to craft a malicious zip file that triggers the specific pointer misuse during decompression operations. When a vulnerable system attempts to unzip such a file, the huft_build function processes the malformed data structure and inadvertently follows an invalid memory pointer, causing the application to crash immediately upon encountering the corrupted data. The nature of this flaw aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-476, which covers null pointer dereference scenarios. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1059.007, where adversaries leverage application-specific vulnerabilities to cause system instability and potential denial of service conditions. The impact extends beyond simple application crashes as it can be leveraged to disrupt services on embedded devices, network appliances, and systems where BusyBox serves as a core component of the operating environment.
From an operational standpoint, this vulnerability poses significant risks to network infrastructure and embedded systems that utilize BusyBox for archive decompression tasks. The crash condition affects not only individual applications but can potentially cause broader system instability when the compromised decompression utility is part of critical system operations. Devices such as routers, firewalls, and IoT appliances that rely on BusyBox for file operations become vulnerable to denial of service attacks through simple zip file manipulation. The exploitation requires minimal technical skill from attackers, as the vulnerability can be triggered by simply presenting a malicious zip file to a vulnerable system, making it particularly dangerous in environments where automatic decompression occurs. Organizations should consider the broader implications of this vulnerability across their embedded infrastructure, as the impact extends from simple service disruption to potential compromise of network security appliances that depend on proper archive handling functionality. The vulnerability highlights the importance of proper memory validation and pointer arithmetic in embedded systems where resource constraints may lead to less rigorous input validation practices.
The recommended mitigation strategy involves upgrading to BusyBox version 1.27.2 or later, which includes the necessary patches to address the pointer misuse in the huft_build function. System administrators should prioritize patching all affected devices, particularly those in network infrastructure and security-critical environments. Additional defensive measures include implementing proper input validation for zip file operations, deploying network monitoring to detect suspicious file transfer patterns, and establishing robust application sandboxing where decompression operations occur in isolated environments. The vulnerability serves as a reminder of the critical importance of proper memory management in embedded systems and the potential for seemingly minor pointer arithmetic errors to result in significant system instability. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across their entire fleet of devices. The incident underscores the necessity of thorough code review processes for core system utilities, particularly in environments where embedded systems are prevalent and traditional security controls may be limited.