CVE-2017-11323 in ALZip
Summary
by MITRE
Stack-based buffer overflow in ESTsoft ALZip 8.51 and earlier allows remote attackers to execute arbitrary code via a crafted MS-DOS device file, as demonstrated by use of "AUX" as the initial substring of a filename.
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Analysis
by VulDB Data Team • 11/09/2019
The vulnerability identified as CVE-2017-11323 represents a critical stack-based buffer overflow flaw within ESTsoft ALZip version 8.51 and earlier installations. This security defect resides in the software's handling of MS-DOS device files, specifically when processing filenames that begin with the substring "AUX". The vulnerability manifests when the application attempts to parse and process these specially crafted filenames without adequate bounds checking, creating an exploitable condition that can be leveraged by remote attackers to gain arbitrary code execution privileges on the target system.
The technical exploitation of this vulnerability stems from improper input validation mechanisms within ALZip's file processing pipeline. When the software encounters a filename starting with "AUX", it fails to properly validate the length and boundaries of the input data before copying it into a fixed-size stack buffer. This classic buffer overflow scenario occurs because the application does not implement sufficient boundary checks or length validation before performing memory operations, allowing an attacker to overwrite adjacent stack memory locations with malicious payload data. The vulnerability specifically targets the application's handling of device files, which are special file types in the MS-DOS and Windows file systems that provide access to hardware devices and system resources.
From an operational perspective, this vulnerability presents a significant risk to organizations relying on ALZip for file compression and decompression operations. Remote attackers can exploit this flaw by crafting malicious archive files containing filenames that begin with "AUX" and delivering them through various attack vectors such as email attachments, web downloads, or file sharing platforms. Once executed, the buffer overflow enables attackers to inject and execute arbitrary code with the privileges of the ALZip process, potentially leading to complete system compromise. The vulnerability's remote exploitability makes it particularly dangerous as it does not require local access or user interaction beyond opening the malicious archive file, aligning with ATT&CK technique T1059.007 for command and scripting interpreter execution.
The impact of this vulnerability extends beyond simple code execution to encompass potential privilege escalation and persistent system compromise. Security researchers have classified this issue under CWE-121, stack-based buffer overflow, which represents a well-known and frequently exploited class of vulnerabilities in software applications. Organizations using ALZip versions prior to 8.52 are particularly at risk, as the vulnerability exists in the core file processing functionality that handles numerous file format types. The exploitability of this vulnerability is further enhanced by its remote nature, making it suitable for automated attack campaigns and large-scale exploitation attempts.
Mitigation strategies for CVE-2017-11323 primarily focus on immediate software updates and implementation of defensive measures. Organizations should prioritize upgrading to ALZip version 8.52 or later, which contains patches addressing the buffer overflow condition through proper input validation and boundary checking mechanisms. Additionally, security administrators should implement network-based protections including firewall rules that restrict access to archive file types, email filtering systems that scan for potentially malicious compressed files, and endpoint protection solutions that monitor for suspicious file processing activities. The vulnerability's classification under CWE-121 emphasizes the importance of input validation practices and proper memory management techniques in software development. Organizations should also consider implementing application whitelisting policies that restrict execution of untrusted archive files, and deploy security awareness training to educate users about the risks of opening suspicious compressed files from unknown sources. These defensive measures align with ATT&CK tactics including T1078 for valid accounts and T1566 for phishing campaigns that may deliver malicious archive files containing the exploit payload.