CVE-2017-14166 in libarchive
Summary
by MITRE
libarchive 3.3.2 allows remote attackers to cause a denial of service (xml_data heap-based buffer over-read and application crash) via a crafted xar archive, related to the mishandling of empty strings in the atol8 function in archive_read_support_format_xar.c.
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Analysis
by VulDB Data Team • 12/28/2022
The vulnerability identified as CVE-2017-14166 affects libarchive version 3.3.2 and represents a critical heap-based buffer over-read condition that can be exploited to achieve remote denial of service. This flaw resides within the xar archive format handling functionality of the library, specifically in the atol8 function located in archive_read_support_format_xar.c. The vulnerability manifests when processing crafted xar archives that contain malformed empty string sequences, leading to improper memory access patterns that ultimately result in application crashes and system instability.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the xar format parser. When the atol8 function encounters empty string data within the archive structure, it fails to properly handle the boundary conditions, causing the application to attempt reading beyond allocated heap memory regions. This buffer over-read condition occurs because the function does not adequately verify the length of input data before performing arithmetic operations that determine memory access offsets. The flaw is categorized under CWE-125 as an out-of-bounds read, which is a common class of memory safety vulnerabilities that can lead to unpredictable application behavior including crashes, data corruption, or potential privilege escalation in some scenarios.
From an operational perspective, this vulnerability poses significant risks to systems that rely on libarchive for processing untrusted archive files, particularly in environments where automated file extraction occurs. Attackers can craft malicious xar archives that, when processed by vulnerable applications, will trigger the buffer over-read condition and cause service disruption. The impact extends beyond simple denial of service as the vulnerability can be leveraged in broader attack chains where persistent service disruption can enable further exploitation attempts or serve as a vector for more sophisticated attacks. Systems utilizing applications such as web servers, file processing services, or automated backup systems that depend on libarchive functionality are particularly at risk.
The mitigation strategies for CVE-2017-14166 primarily involve immediate patching of affected libarchive versions to 3.3.3 or later, which contains the necessary fixes for the atol8 function's memory handling. Organizations should also implement proper input validation and sanitization measures for archive files, particularly in environments where untrusted content is processed. Network segmentation and access controls can help limit the potential impact of exploitation attempts. Additionally, monitoring systems should be configured to detect unusual application crash patterns or memory access violations that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and demonstrates the importance of maintaining up-to-date security libraries in enterprise environments. Regular security assessments and vulnerability scanning should include checks for libarchive versions to prevent exploitation of similar memory safety issues that may exist in other components of the software stack.