CVE-2017-12624 in CXF
Summary
by MITRE
Apache CXF supports sending and receiving attachments via either the JAX-WS or JAX-RS specifications. It is possible to craft a message attachment header that could lead to a Denial of Service (DoS) attack on a CXF web service provider. Both JAX-WS and JAX-RS services are vulnerable to this attack. From Apache CXF 3.2.1 and 3.1.14, message attachment headers that are greater than 300 characters will be rejected by default. This value is configurable via the property "attachment-max-header-size".
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Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-12624 affects Apache CXF implementations that support message attachments through JAX-WS and JAX-RS specifications. This issue represents a classic denial of service vulnerability that exploits the way CXF processes attachment headers in web service communications. The flaw allows malicious actors to craft specially formatted message attachment headers that can overwhelm the service provider's processing capabilities, effectively rendering the web service unavailable to legitimate users.
The technical implementation of this vulnerability stems from insufficient input validation within the CXF framework's attachment handling mechanism. When processing message attachments, CXF parses header information to determine how to handle the attached content. The vulnerability occurs because the system does not properly limit the size of attachment headers, allowing attackers to submit headers exceeding normal parameters. This lack of size restriction creates a condition where the service provider's memory allocation and processing resources become consumed unnecessarily, leading to system instability and service unavailability.
The operational impact of this vulnerability extends across both JAX-WS and JAX-RS service implementations within Apache CXF, making it particularly dangerous as it affects a broad range of web service deployments. Attackers can exploit this weakness by crafting malicious attachment headers that exceed the default threshold of 300 characters, causing the service to either reject the message or consume excessive resources during processing. This vulnerability aligns with CWE-122, which describes buffer overflow conditions, and demonstrates how improper input handling can lead to resource exhaustion attacks. The attack vector operates at the protocol level, making it difficult to detect through traditional network monitoring approaches since the malicious behavior appears as legitimate service traffic.
The remediation approach for CVE-2017-12624 involves configuring the "attachment-max-header-size" property within CXF implementations to limit the maximum size of attachment headers. This configuration parameter provides administrators with the flexibility to adjust the threshold based on their specific deployment requirements while maintaining protection against resource exhaustion attacks. The default setting of 300 characters introduced in Apache CXF versions 3.2.1 and 3.1.14 represents a reasonable balance between functionality and security. Organizations should implement this mitigation as part of their standard security configuration practices and consider additional monitoring for unusual attachment header sizes. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and highlights the importance of input validation in preventing resource exhaustion scenarios that can lead to complete service disruption.