CVE-2021-21871 in PowerISO
Summary
by MITRE • 06/30/2021
A memory corruption vulnerability exists in the DMG File Format Handler functionality of PowerISO 7.9. A specially crafted DMG file can lead to an out-of-bounds write. An attacker can provide a malicious file to trigger this vulnerability. The vendor fixed it in a bug-release of the current version.
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Analysis
by VulDB Data Team • 07/04/2021
The vulnerability identified as CVE-2021-21871 represents a critical memory corruption flaw within PowerISO version 7.9's DMG file format handler component. This issue manifests as an out-of-bounds write condition that occurs when processing specially crafted DMG (Disk Image) files, making it particularly dangerous for users who may encounter or open malicious disk images without proper security measures. The vulnerability resides in the software's handling of DMG file structures, where insufficient input validation and memory management controls allow attackers to manipulate the application's memory layout through crafted file content. The flaw specifically affects the parsing logic that interprets DMG file headers and metadata, creating an opportunity for arbitrary memory modification that could lead to system compromise or denial of service conditions.
The technical exploitation of this vulnerability follows a well-established pattern where an attacker crafts a DMG file containing malformed or oversized data structures that exceed the allocated memory boundaries during processing. This out-of-bounds write condition can overwrite adjacent memory locations, potentially corrupting critical application data structures or even executing arbitrary code within the context of the running PowerISO process. The vulnerability's impact is amplified by the fact that DMG files are commonly used for distributing software and system images, making them a prime target for social engineering attacks. According to CWE classification, this vulnerability maps to CWE-787 Out-of-bounds Write, which is categorized under the broader weakness of improper restriction of operations within a limited memory buffer. The flaw demonstrates characteristics consistent with buffer overflow conditions where the application fails to properly validate input data against expected boundaries, creating a pathway for memory corruption that can be leveraged for privilege escalation or system compromise.
From an operational perspective, this vulnerability creates significant risk for organizations and individual users who rely on PowerISO for disk image management and file operations. The attack vector is particularly concerning because it requires only that a user open or interact with a malicious DMG file, making it susceptible to phishing campaigns, malicious email attachments, or compromised download sources. The vulnerability's exploitation potential aligns with ATT&CK technique T1059 Command and Scripting Interpreter, as successful exploitation could enable attackers to execute commands within the application's execution context. Additionally, the flaw could be leveraged for privilege escalation attacks if the PowerISO application runs with elevated privileges, potentially allowing attackers to gain administrative access to affected systems. The risk assessment indicates that this vulnerability could be exploited in the wild, particularly in environments where users frequently handle disk images or where the application is used in automated processes. Organizations should consider this vulnerability as a medium to high severity threat given its potential for remote code execution and the common usage patterns of DMG files in software distribution.
The vendor addressed this vulnerability through a bug-fix release that updated the DMG file format handler to implement proper input validation and memory boundary checks. This remediation approach aligns with standard security practices for buffer overflow vulnerabilities, where the fix involves ensuring that all input data is properly validated against expected size constraints before processing. The updated version demonstrates proper memory management controls that prevent out-of-bounds writes by implementing bounds checking mechanisms and proper buffer allocation strategies. Users should immediately update to the patched version of PowerISO to eliminate exposure to this vulnerability. Security teams should monitor for any potential exploitation attempts in their environments and consider implementing additional safeguards such as application whitelisting, file type restrictions, and network-based protections to prevent users from inadvertently opening malicious DMG files. The vulnerability also highlights the importance of regular security updates and proper input validation in file processing applications, particularly those handling complex binary formats like DMG files that require careful parsing and memory management to prevent similar issues in the future.