CVE-2007-5793 in StoneGate IPS
Summary
by MITRE
Stonesoft StoneGate IPS before 4.0 does not properly decode Fullwidth/Halfwidth Unicode encoded data, which makes it easier for remote attackers to scan or penetrate systems and avoid detection.
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Analysis
by VulDB Data Team • 07/24/2024
The vulnerability identified as CVE-2007-5793 affects Stonesoft StoneGate IPS version 4.0 and earlier, representing a significant weakness in the system's ability to process Unicode encoded data. This flaw specifically manifests in the improper decoding of Fullwidth/Halfwidth Unicode character mappings, which are part of the Unicode standard designed to provide compatibility between different character encodings. The issue stems from the intrusion prevention system's failure to correctly interpret these specific Unicode sequences that can represent the same characters in different visual forms, creating a critical gap in security monitoring capabilities.
The technical implementation flaw occurs when the StoneGate IPS system encounters network traffic containing Fullwidth/Halfwidth Unicode sequences that are commonly used in evasion techniques by attackers. These Unicode mappings include characters like fullwidth Latin letters, fullwidth digits, and other compatibility characters that appear visually identical to their standard ASCII counterparts but have different Unicode code points. When the system fails to properly decode these sequences, it creates a parsing inconsistency that allows malicious traffic to bypass security controls that would normally detect suspicious patterns or payloads. This misinterpretation specifically affects the system's deep packet inspection capabilities and signature matching mechanisms.
The operational impact of this vulnerability extends beyond simple detection failures, as it creates opportunities for remote attackers to conduct reconnaissance activities and execute penetration attempts without triggering security alerts. Attackers can exploit this weakness by crafting malicious payloads that utilize Fullwidth/Halfwidth Unicode encoding to evade intrusion detection systems, making it significantly easier to perform port scanning, service enumeration, and other reconnaissance activities. The vulnerability essentially creates a stealth mechanism that allows attackers to bypass network security controls while maintaining their activities within the bounds of what appears to be normal network traffic, thereby undermining the fundamental purpose of the intrusion prevention system.
This vulnerability aligns with CWE-184, which addresses incomplete or missing Unicode normalization, and represents a classic example of how Unicode handling issues can create security gaps in network security systems. From an ATT&CK framework perspective, this weakness maps to techniques involving evasion and command and control communication, specifically targeting the defense evasion tactics that allow adversaries to avoid detection. The vulnerability also connects to broader security concepts related to input validation and character encoding normalization that are fundamental to preventing injection attacks and maintaining system integrity.
Organizations should implement immediate mitigations including updating to Stonesoft StoneGate IPS version 4.0 or later, which contains the necessary patches to properly handle Fullwidth/Halfwidth Unicode sequences. Network administrators should also consider implementing additional monitoring for unusual Unicode character patterns in network traffic and establishing more robust logging mechanisms to detect potential exploitation attempts. The fix typically involves updating the system's Unicode processing libraries and ensuring that all character encoding normalization procedures are properly implemented across the intrusion prevention system's inspection paths. Security teams should also conduct comprehensive testing to verify that the updated system correctly handles all Unicode character mappings and that existing security policies remain effective against newly detected threats.