CVE-2016-8275 in AnyOffice
Summary
by MITRE
Huawei AnyOffice V200R006C00 could allow an authenticated, remote attacker to cause the software to deny services by uploading an XML bomb.
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Analysis
by VulDB Data Team • 11/24/2022
The vulnerability identified as CVE-2016-8275 affects Huawei AnyOffice V200R006C00 software, representing a significant denial of service weakness that can be exploited by authenticated remote attackers. This flaw specifically manifests through the improper handling of XML data structures during file upload operations, creating a potential pathway for service disruption attacks. The vulnerability resides within the software's XML parsing mechanisms, where insufficient input validation allows maliciously crafted XML documents to trigger resource exhaustion conditions. The affected system processes XML content without adequate safeguards against malformed or oversized data structures, making it susceptible to exploitation by adversaries who can upload specially crafted files to initiate denial of service conditions.
The technical exploitation of this vulnerability occurs when an authenticated attacker uploads an XML bomb, also known as an XML entity expansion attack, to the AnyOffice system. This attack leverages the recursive expansion of XML entities to consume excessive system resources including memory and processing power. The XML bomb typically contains malicious entity declarations that reference each other in recursive patterns, causing the parser to expand these entities repeatedly until system resources are exhausted. The vulnerability stems from the software's failure to implement proper XML parsing limits and resource constraints, allowing the XML parser to continue processing without adequate safeguards against exponential entity expansion. This type of attack directly maps to CWE-400, which classifies excessive resource consumption as a vulnerability category, and more specifically to CWE-129, which addresses improper validation of input length and size.
The operational impact of CVE-2016-8275 extends beyond simple service disruption to potentially compromise the availability of critical business operations that depend on the AnyOffice platform. When exploited successfully, the XML bomb attack can cause the system to become unresponsive, crash, or consume all available memory and CPU resources, effectively rendering the service unusable for legitimate users. This vulnerability affects not only the immediate availability of the AnyOffice service but can also impact downstream applications and systems that rely on its functionality. The authenticated nature of the attack means that adversaries must first establish valid credentials, but once inside the system, they can cause significant disruption without requiring additional privileges or complex attack vectors. The impact is particularly concerning in enterprise environments where AnyOffice serves as a critical component for remote access and collaboration services, as the denial of service can affect multiple users simultaneously and potentially disrupt business continuity.
Mitigation strategies for CVE-2016-8275 should focus on implementing robust XML parsing controls and resource limitations to prevent the exploitation of XML bomb attacks. Organizations should configure the AnyOffice system to enforce strict limits on XML document size, entity expansion depth, and processing time to prevent resource exhaustion. The implementation of XML parsers with built-in protection mechanisms against excessive entity expansion, such as those found in modern XML libraries with secure parsing modes, should be prioritized. Additionally, network segmentation and access controls should be enforced to limit the scope of potential attacks, ensuring that only authorized users can upload files to the system. Regular security updates and patches from Huawei should be implemented promptly, as the vendor likely released fixes for this vulnerability in subsequent software versions. The mitigation approach aligns with ATT&CK technique T1499, which focuses on network denial of service attacks, and emphasizes the importance of input validation and resource management as primary defense mechanisms against such threats. Security monitoring should be enhanced to detect unusual upload patterns and resource consumption spikes that may indicate exploitation attempts, while access logging should be maintained to track all file upload activities for forensic analysis.