CVE-2015-7762 in OpenAFS
Summary
by MITRE
rx/rx.c in OpenAFS before 1.6.15 and 1.7.x before 1.7.33 does not properly initialize the padding of a data structure when constructing 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-2015-7762 affects the OpenAFS distributed file system implementation, specifically within the rx/rx.c component responsible for handling Rx protocol acknowledgements. This flaw exists in versions prior to 1.6.15 and 1.7.x prior to 1.7.33, representing a critical security issue that undermines the integrity of network communications within the system. The vulnerability stems from improper initialization of padding bytes within a data structure used during ACK packet construction, creating potential information disclosure risks that can be exploited remotely.
The technical root cause of this vulnerability lies in the insufficient initialization of memory padding fields within the Rx protocol implementation. When constructing acknowledgment packets, the system fails to properly zero out or initialize padding bytes within the data structure, leaving behind uninitialized memory contents that may contain sensitive information from previous operations. This memory leakage occurs during the packet construction process where the padding bytes are not explicitly cleared before being included in the network transmission. The flaw is particularly concerning because it affects the fundamental communication mechanisms of the distributed file system, where these ACK packets are regularly transmitted between clients and servers.
The operational impact of this vulnerability is significant as it enables remote attackers to potentially obtain sensitive information through two distinct attack vectors. The first vector involves conducting replay attacks where attackers can capture and reuse previously transmitted ACK packets, exploiting the uninitialized padding to extract information that was present in memory when the packet was originally constructed. The second vector utilizes network sniffing capabilities where attackers can intercept network traffic and analyze the padding bytes within ACK packets to recover sensitive data that may include system information, authentication tokens, or other confidential data from the host system. This vulnerability directly violates the principle of least privilege and can lead to information disclosure that may enable further exploitation attempts.
The security implications extend beyond simple information disclosure, as this vulnerability can contribute to broader attack surface exploitation within distributed systems. According to CWE classification, this represents a weakness in the initialization of data structures, specifically CWE-457: Use of Uninitialized Variable, which can lead to information exposure through uninitialized memory contents. The vulnerability aligns with ATT&CK technique T1041: Exfiltration Over C2 Channel, as the uninitialized memory can be leveraged to extract sensitive data through network communications. Organizations utilizing OpenAFS versions affected by this vulnerability face risks of credential exposure, system reconnaissance, and potential privilege escalation attacks that could compromise the integrity of their distributed file systems.
Mitigation strategies for CVE-2015-7762 require immediate patching of affected OpenAFS installations to versions 1.6.15 or 1.7.33 and 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, particularly focusing on anomalous ACK packet structures. Additional defensive measures include network segmentation to limit exposure, implementing strict access controls for OpenAFS services, and conducting thorough security assessments of distributed system communications. The fix implemented in patched versions ensures that all padding bytes within the Rx protocol data structures are properly initialized before packet construction, eliminating the information leakage vector that made this vulnerability exploitable. Organizations should also consider implementing network intrusion detection systems specifically configured to identify potential replay attack patterns and unauthorized packet analysis attempts that could exploit similar uninitialized memory issues.