CVE-2015-7763 in OpenAFS
Summary
by MITRE
rx/rx.c in OpenAFS 1.5.75 through 1.5.78, 1.6.x before 1.6.15, and 1.7.x before 1.7.33 does not properly initialize padding at the end of an Rx acknowledgement (ACK) packet, which allows remote attackers to obtain sensitive information by (1) conducting a replay attack or (2) sniffing the network.
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Analysis
by VulDB Data Team • 06/26/2022
The vulnerability identified as CVE-2015-7763 resides within the OpenAFS distributed file system implementation, specifically in the rx/rx.c component responsible for handling Rx protocol acknowledgments. This flaw affects multiple versions of OpenAFS including the 1.5.x series through 1.5.78, 1.6.x versions before 1.6.15, and 1.7.x versions before 1.7.33. The core issue manifests when the system fails to properly initialize padding bytes at the end of Rx acknowledgment packets, creating a potential information disclosure risk that can be exploited by remote attackers through network-based attacks.
The technical nature of this vulnerability stems from improper memory initialization practices within the Rx protocol implementation. When Rx acknowledgment packets are constructed, the padding bytes that should be explicitly initialized to known values remain uninitialized, potentially containing residual data from previous operations. This uninitialized padding can contain sensitive information such as cryptographic keys, session tokens, or other confidential data that was previously stored in memory locations now used for packet construction. The flaw creates a situation where attackers can potentially recover this uninitialized data through network sniffing or by conducting replay attacks against the system.
The operational impact of this vulnerability is significant within distributed file system environments where OpenAFS is deployed. Attackers can exploit this weakness to conduct passive network monitoring attacks, where they capture network traffic and analyze the uninitialized padding bytes in Rx acknowledgment packets to extract sensitive information. The vulnerability is particularly concerning because it can be exploited through simple network sniffing without requiring active participation in the network communication, making it an attractive target for attackers seeking to gather intelligence about the system. Additionally, the replay attack vector allows for more sophisticated exploitation where attackers can manipulate captured packets to extract information or potentially impersonate legitimate system components.
This vulnerability maps to CWE-1278, which specifically addresses the improper initialization of memory in distributed systems, and aligns with ATT&CK technique T1041 for data compression and T1566 for credential access through network sniffing. The attack surface is particularly relevant in enterprise environments where OpenAFS is used for file sharing and authentication, as the extracted information could potentially be used to escalate privileges or gain unauthorized access to protected resources. Organizations using affected OpenAFS versions should prioritize patching to address this information disclosure vulnerability that could compromise the confidentiality of network communications.
The recommended mitigation strategy involves upgrading to patched versions of OpenAFS, specifically versions 1.5.79, 1.6.15, and 1.7.33 or later, which contain the necessary fixes for proper padding initialization. System administrators should also implement network monitoring to detect unusual traffic patterns that might indicate exploitation attempts, while ensuring that network segmentation and access controls are properly configured to limit the potential impact of any successful exploitation. Additionally, organizations should conduct regular security assessments to identify other potential information disclosure vulnerabilities in their distributed systems and maintain up-to-date security patches for all network services.