CVE-2017-9928 in lrzip
Summary
by MITRE
In lrzip 0.631, a stack buffer overflow was found in the function get_fileinfo in lrzip.c:979, which allows attackers to cause a denial of service via a crafted file.
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Analysis
by VulDB Data Team • 12/09/2022
The vulnerability identified as CVE-2017-9928 represents a critical stack buffer overflow flaw within the lrzip compression utility version 0.631. This issue resides in the get_fileinfo function located in the lrzip.c source file at line 979, where improper input validation and memory management practices create an exploitable condition that can be leveraged by malicious actors to disrupt system operations. The lrzip utility is commonly used for compressing and decompressing files, making this vulnerability particularly concerning for environments where such compression tools are extensively utilized. The flaw arises from insufficient bounds checking when processing file metadata information, allowing an attacker to craft specially formatted input files that trigger the buffer overflow condition during normal operation of the compression utility.
The technical implementation of this vulnerability follows a classic stack-based buffer overflow pattern that aligns with CWE-121, which describes the condition where a program writes data to a buffer that is insufficiently sized to hold the data being written. In this specific case, the get_fileinfo function fails to properly validate the length of input data before copying it into a fixed-size stack buffer, creating a scenario where an attacker can overflow the buffer and potentially overwrite adjacent stack memory locations. This condition can be exploited through careful crafting of input files that contain maliciously formatted metadata, causing the program to execute unintended code paths or simply crash the application. The vulnerability demonstrates poor defensive programming practices and lacks proper input sanitization mechanisms that would normally prevent such memory corruption scenarios from occurring.
The operational impact of CVE-2017-9928 extends beyond simple denial of service conditions, as it can be leveraged to create more sophisticated attack vectors within systems that rely on lrzip for file processing operations. When exploited, the buffer overflow can cause the lrzip utility to crash or behave unpredictably, potentially leading to service disruption for legitimate users who depend on compression functionality. This vulnerability is particularly dangerous in automated environments or systems that process untrusted file inputs, where an attacker could craft malicious files that trigger the overflow during routine compression operations. The attack surface is broad given that lrzip is used in various contexts including backup systems, file transfer applications, and automated processing pipelines where file integrity checks may not be comprehensive enough to prevent exploitation. Additionally, the vulnerability can be classified under ATT&CK technique T1203, which involves the use of file decompression or extraction to execute malicious code, making it a potential entry point for more complex attack chains.
Mitigation strategies for CVE-2017-9928 should prioritize immediate software updates to versions that have patched the buffer overflow vulnerability, as this represents the most effective defense against exploitation. System administrators should implement comprehensive input validation and sanitization procedures for any files processed through lrzip, including implementing file type checks and size limitations to prevent overly large or malformed inputs from reaching the vulnerable function. The implementation of stack protection mechanisms such as stack canaries and address space layout randomization can provide additional defense-in-depth layers, though these measures are secondary to the core fix of properly validating buffer boundaries. Organizations should also consider implementing monitoring and alerting systems to detect unusual lrzip behavior or crash patterns that might indicate exploitation attempts. Furthermore, the vulnerability underscores the importance of regular security assessments and code reviews to identify similar patterns in other software components, particularly in legacy systems where buffer overflow vulnerabilities are more prevalent due to older coding practices and insufficient security testing protocols.