CVE-2017-15873 in BusyBox
Summary
by MITRE
The get_next_block function in archival/libarchive/decompress_bunzip2.c in BusyBox 1.27.2 has an Integer Overflow that may lead to a write access violation.
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Analysis
by VulDB Data Team • 06/09/2025
The vulnerability identified as CVE-2017-15873 resides within the BusyBox 1.27.2 archive handling component, specifically in the get_next_block function located in archival/libarchive/decompress_bunzip2.c. This integer overflow flaw represents a critical security weakness that can be exploited to cause memory corruption and potentially enable arbitrary code execution. The issue manifests when processing bzip2 compressed archives, making it particularly dangerous in environments where untrusted archive files are processed, such as in automated build systems, file upload handlers, or network-based file processing services.
The technical root cause of this vulnerability stems from improper input validation and integer arithmetic handling within the decompression logic. When the get_next_block function processes compressed data, it fails to properly validate the size parameters before performing arithmetic operations that could result in integer overflow conditions. This overflow can cause the function to calculate incorrect buffer sizes or memory allocation values, leading to situations where the program attempts to write data beyond the boundaries of allocated memory regions. Such memory corruption scenarios create opportunities for attackers to manipulate program execution flow or cause denial of service conditions through controlled memory access violations.
From an operational impact perspective, this vulnerability affects systems running BusyBox 1.27.2 that process untrusted bzip2 compressed files, which includes numerous embedded systems, router firmware, and lightweight Linux distributions. The vulnerability can be exploited through maliciously crafted archive files that trigger the integer overflow condition during decompression, potentially allowing remote attackers to execute arbitrary code with the privileges of the affected process. The ATT&CK framework categorizes this as a memory corruption vulnerability that could be leveraged for privilege escalation or persistent access, while CWE-190 specifically identifies integer overflow conditions as a common source of memory safety issues. Organizations relying on BusyBox for file operations, particularly in network-facing services or automated processing pipelines, face significant risk exposure.
Mitigation strategies for CVE-2017-15873 should prioritize immediate patching of affected BusyBox installations to version 1.27.3 or later, which contains the necessary fixes for the integer overflow condition. System administrators should also implement strict input validation and sanitization measures for all archive processing operations, including implementing file size limits and content type verification before decompression. Network segmentation and access controls can help limit the potential impact of exploitation attempts, while monitoring solutions should be deployed to detect unusual decompression patterns or memory access violations that could indicate exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments of their embedded systems and firmware components to identify other potentially affected versions of BusyBox or similar integer overflow vulnerabilities in related software libraries. The fix implemented in the patched version addresses the specific arithmetic operations that led to the overflow condition, ensuring proper bounds checking and integer validation before memory allocation occurs.