CVE-2011-1336 in ALZip
Summary
by MITRE
Buffer overflow in ALZip 8.21 and earlier allows remote attackers to execute arbitrary code via a crafted mim file.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 01/15/2025
The vulnerability identified as CVE-2011-1336 represents a critical buffer overflow flaw within ALZip version 8.21 and earlier implementations. This security weakness resides in the software's handling of maliciously crafted mim files, which are typically used for storing compressed data. The flaw stems from insufficient input validation and bounds checking mechanisms within the decompression routine that processes these file formats. When a malicious user constructs a specially crafted mim file containing oversized data structures or malformed headers, the application fails to properly validate the input size before attempting to copy data into fixed-size memory buffers. This fundamental programming error creates a condition where attacker-controlled data can overwrite adjacent memory locations, potentially corrupting program execution flow and enabling arbitrary code execution.
The technical exploitation of this vulnerability follows a classic buffer overflow attack pattern where the attacker crafts a mim file containing more data than the allocated buffer can accommodate. According to CWE-121, this represents a classic stack-based buffer overflow condition where insufficient bounds checking allows data to overwrite adjacent memory regions including return addresses and control data. The vulnerability's remote exploitation capability means that attackers can trigger the flaw through network-based delivery mechanisms without requiring local system access, making it particularly dangerous in web environments where users might unknowingly download and open malicious files. The attack vector specifically targets the decompression engine within ALZip, which processes mim files as part of its normal operation, making this flaw particularly insidious as legitimate file processing activities become potential attack vectors.
The operational impact of CVE-2011-1336 extends beyond simple code execution to encompass potential system compromise and data theft. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with the privileges of the user running ALZip, potentially leading to complete system compromise if the application runs with elevated permissions. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution, as the payload execution often involves spawning command shells or executing additional malware components. The attack can result in persistent backdoors, data exfiltration, or further network propagation, particularly in enterprise environments where ALZip might be used for document distribution. Organizations using vulnerable versions face significant risk as the exploitation can occur through simple email attachments, web downloads, or automated file processing systems that automatically decompress mim files.
Mitigation strategies for CVE-2011-1336 focus on both immediate remediation and long-term architectural improvements. The primary recommendation involves upgrading to ALZip version 8.22 or later, where the buffer overflow has been addressed through proper bounds checking and input validation mechanisms. Organizations should implement strict file validation policies that prevent automatic processing of unknown or untrusted mim files, particularly in environments where users might encounter malicious attachments. Network-level protections such as email filtering, web application firewalls, and content inspection systems can help detect and block malicious mim file deliveries before they reach end-user systems. Additionally, system hardening measures including stack protection mechanisms, address space layout randomization, and DEP/NX bit enforcement can provide defense-in-depth protection against exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify other potentially vulnerable applications within the enterprise environment, as similar buffer overflow patterns may exist in other decompression libraries or file processing tools that share similar code bases or development practices.