CVE-2007-3971 in NOD32 Antivirus
Summary
by MITRE
Integer overflow in ESET NOD32 Antivirus before 2.2289 allows remote attackers to cause a denial of service (CPU and disk consumption) via a crafted ASPACK packed file, which triggers an infinite loop.
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Analysis
by VulDB Data Team • 07/22/2019
The vulnerability identified as CVE-2007-3971 represents a critical integer overflow flaw within ESET NOD32 Antivirus software prior to version 2.2289. This issue manifests when the antivirus engine processes specifically crafted ASPACK packed files, creating a condition where the software's internal counters exceed their maximum representable values. The flaw operates at the core of the antivirus's file processing logic, where integer variables used to track file decompression and analysis operations become corrupted due to overflow conditions. When an attacker crafts a malicious file using the ASPACK packing technique, the antivirus engine attempts to unpack and analyze the file, but the integer overflow causes the processing loop to behave unpredictably. The vulnerability specifically triggers an infinite loop within the decompression routine, where the counter variables that control the loop iterations become negative or excessively large values, causing the software to continuously process the same file segment without proper termination conditions. This flaw exists within the software's unpacking engine that handles various packed file formats, including those created by the ASPACK packer utility commonly used by malware authors to obfuscate their payloads.
The operational impact of this vulnerability extends beyond simple denial of service to create substantial resource exhaustion conditions that can severely impact system performance and availability. When exploited, the infinite loop causes the antivirus software to consume excessive cpu cycles as it repeatedly processes the malformed file, while simultaneously generating massive disk I/O operations during the continuous unpacking attempts. The resource consumption pattern creates a sustained high load on both the cpu and disk subsystems, potentially causing the system to become unresponsive or significantly degraded in performance. The vulnerability affects the antivirus engine's ability to properly handle legitimate files, as the system becomes overwhelmed with the continuous processing of the maliciously crafted file. Network performance may also be impacted as the antivirus software consumes bandwidth during the continuous scanning and processing operations, and the system may experience memory exhaustion as the engine attempts to maintain state information for the malformed file processing. This type of resource exhaustion attack falls under the category of denial of service vulnerabilities that can be exploited remotely without requiring authentication or special privileges.
The technical exploitation of this vulnerability requires the attacker to craft a specific file using the ASPACK packing utility with precise parameters that will trigger the integer overflow condition within the ESET NOD32 engine. The flaw demonstrates poor input validation and inadequate boundary checking within the unpacking routines, where the software does not properly verify that counter values remain within acceptable ranges during file processing operations. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses issues where integer arithmetic operations produce results that exceed the maximum value that can be represented by the data type. The attack pattern follows the typical remote code execution or denial of service methodology where an attacker can deliver a malicious file through various vectors including email attachments, web downloads, or removable media. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, Network Denial of Service, and T1566.001, Phishing, as attackers can deliver the malicious files through email campaigns or web-based attacks to trigger the vulnerable condition.
Mitigation strategies for this vulnerability require immediate patching of the ESET NOD32 antivirus software to version 2.2289 or later, which includes proper integer overflow protections and enhanced input validation routines. System administrators should implement network monitoring to detect unusual cpu and disk usage patterns that may indicate exploitation attempts, particularly when processing files from untrusted sources. The antivirus software should be configured with proper timeout mechanisms to prevent indefinite processing of suspicious files, and network segmentation should be implemented to limit the potential impact of successful exploitation attempts. Organizations should also consider implementing additional security controls such as email filtering, web proxies, and application whitelisting to reduce the attack surface and prevent users from inadvertently executing malicious files. Regular security assessments and vulnerability scanning should be conducted to identify other potential integer overflow conditions within the antivirus engine and related security software. The fix implemented by ESET addresses the root cause by adding proper boundary checks and overflow detection mechanisms within the unpacking routines, ensuring that counter variables are validated before being used in loop conditions and that appropriate error handling is implemented when processing malformed input files.