CVE-2021-27623 in Internet Graphics Service
Summary
by MITRE • 06/09/2021
SAP Internet Graphics Service, versions - 7.20,7.20EXT,7.53,7.20_EX2,7.81, allows an unauthenticated attacker after retrieving an existing system state value can submit a malicious IGS request over a network which due to insufficient input validation in method CXmlUtility::CheckLength() which will trigger an internal memory corruption error in the system causing the system to crash and rendering it unavailable. In this attack, no data in the system can be viewed or modified.
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Analysis
by VulDB Data Team • 06/12/2021
The vulnerability identified as CVE-2021-27623 affects SAP Internet Graphics Service components across multiple version releases including 7.20, 7.20EXT, 7.53, 7.20_EX2, and 7.81. This security flaw represents a critical weakness in the system's input validation mechanisms within the CXmlUtility::CheckLength() method, which operates as a core component for processing XML data within the Internet Graphics Service framework. The vulnerability specifically targets the system's memory management capabilities and demonstrates a classic example of insufficient input validation that can lead to memory corruption errors.
The attack vector requires an unauthenticated attacker who must first obtain an existing system state value before executing a malicious IGS request over the network. This prerequisite indicates that while the vulnerability does not require authentication to exploit, it does necessitate some level of reconnaissance to gather necessary system information. The flaw manifests when the system processes XML input through the vulnerable CXmlUtility::CheckLength() method, which fails to properly validate input parameters before processing them. This inadequate validation allows maliciously crafted input to trigger internal memory corruption that ultimately results in system crashes and complete service unavailability.
From a technical perspective, this vulnerability operates as a memory corruption issue that aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap memory. The flaw specifically impacts the system's ability to maintain stable operation during XML processing operations, as the insufficient input validation in the CheckLength() method allows attackers to manipulate memory structures in ways that were not anticipated during system design. The system's response to this manipulation is a complete crash, which constitutes a denial of service condition that severely impacts availability.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader business continuity concerns for organizations relying on SAP Internet Graphics Service for their operations. The fact that no data can be viewed or modified during this attack indicates that the flaw is primarily a denial of service vector rather than a data compromise mechanism, yet the system crash renders services completely unavailable to legitimate users. This type of vulnerability is particularly concerning in enterprise environments where SAP systems often serve as foundational components for business-critical applications, as the resulting service unavailability can cascade through dependent systems and processes.
Organizations should implement immediate mitigations including applying the relevant SAP security patches and updates that address this specific vulnerability in the CXmlUtility::CheckLength() method. Network segmentation and access controls should be reinforced to limit potential attack surfaces, while monitoring systems should be enhanced to detect anomalous XML processing patterns that might indicate exploitation attempts. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a significant concern for organizations following the principle of least privilege as it allows unauthenticated attackers to cause system-wide disruptions without requiring access to system credentials or data. Additionally, this vulnerability demonstrates the importance of proper input validation as outlined in the OWASP Top Ten security principles, specifically addressing the need for robust sanitization of all input parameters before processing.