CVE-2017-15874 in BusyBox
Summary
by MITRE
archival/libarchive/decompress_unlzma.c in BusyBox 1.27.2 has an Integer Underflow that leads to a read access violation.
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Analysis
by VulDB Data Team • 06/09/2025
The vulnerability identified as CVE-2017-15874 resides within the libarchive component of BusyBox version 1.27.2, specifically in the decompress_unlzma.c file responsible for handling lzma compressed data. This issue manifests as an integer underflow during the decompression process, creating a critical security flaw that can be exploited by malicious actors. The vulnerability occurs when the decompression routine fails to properly validate input parameters, particularly those related to the size calculations required for lzma decompression operations. When an attacker provides carefully crafted malicious input data, the integer underflow causes the decompression code to attempt reading from invalid memory addresses, resulting in a read access violation that can potentially lead to system crashes or arbitrary code execution.
The technical implementation of this vulnerability stems from improper handling of unsigned integer arithmetic within the lzma decompression algorithm. During the decompression process, the code performs calculations that assume positive integer values, but when input data contains values that cause underflow conditions, the resulting negative or unexpectedly large values trigger memory access violations. This flaw directly maps to CWE-191, which categorizes integer underflow conditions as a common vulnerability pattern that can lead to memory corruption. The vulnerability is particularly dangerous because it occurs during decompression operations, which are frequently invoked when processing user-provided files or network data, making it exploitable through various attack vectors including file uploads, network protocol processing, or any scenario where lzma compressed data is handled.
The operational impact of CVE-2017-15874 extends beyond simple system instability, as it represents a potential path for remote code execution in environments where BusyBox is deployed with insufficient input validation. Systems running vulnerable versions of BusyBox are at risk when processing untrusted compressed data, including web applications, embedded systems, and network services that utilize lzma decompression functionality. The vulnerability can be exploited through the ATT&CK technique of "Exploitation for Client Execution" where malicious compressed files are delivered to systems and automatically processed by BusyBox components. This creates a significant risk for embedded devices, network appliances, and containers that rely on BusyBox for core system operations, as these environments often process compressed data from untrusted sources without adequate sanitization.
Mitigation strategies for this vulnerability require immediate patching of affected BusyBox installations to version 1.27.3 or later, which contains the necessary fixes for the integer underflow condition. Organizations should also implement input validation controls that sanitize compressed data before processing, particularly for systems that handle user uploads or network data. The fix typically involves adding proper bounds checking and integer overflow protection mechanisms within the decompression routines to prevent underflow conditions from occurring. Security teams should conduct comprehensive vulnerability assessments to identify all systems running vulnerable versions of BusyBox, particularly in embedded environments where patching may be challenging. Additionally, monitoring systems should be configured to detect unusual decompression activity or memory access patterns that might indicate exploitation attempts, as the vulnerability may be used in conjunction with other attack techniques to establish persistent access to compromised systems.