CVE-2016-10377 in vSwitch
Summary
by MITRE
In Open vSwitch (OvS) 2.5.0, a malformed IP packet can cause the switch to read past the end of the packet buffer due to an unsigned integer underflow in `lib/flow.c` in the function `miniflow_extract`, permitting remote bypass of the access control list enforced by the switch.
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Analysis
by VulDB Data Team • 10/03/2020
The vulnerability identified as CVE-2016-10377 represents a critical buffer over-read condition within Open vSwitch version 2.5.0 that fundamentally undermines the network security posture of systems relying on this virtual switching infrastructure. This flaw exists within the packet processing pipeline where the switch attempts to extract flow information from incoming packets, specifically within the miniflow_extract function located in the lib/flow.c source file. The vulnerability manifests when the switch encounters malformed IP packets that trigger an unsigned integer underflow, causing the software to access memory locations beyond the intended packet buffer boundaries.
The technical root cause of this vulnerability stems from improper input validation and boundary checking within the packet parsing logic of Open vSwitch. When processing IP packets, the system fails to adequately verify packet structure integrity before performing arithmetic operations that determine buffer access limits. The unsigned integer underflow occurs during the calculation of packet offsets, where a subtraction operation results in a value that wraps around to a large positive number due to the unsigned nature of the data type. This condition allows attackers to craft specially malformed packets that cause the switch to read memory beyond the legitimate packet data, potentially exposing sensitive information or enabling arbitrary code execution.
From an operational perspective, this vulnerability directly compromises the access control mechanisms that Open vSwitch enforces, creating a remote exploitation vector that bypasses network security policies. The impact extends beyond simple information disclosure as the buffer over-read could potentially enable privilege escalation or denial of service conditions within the switch infrastructure. Network administrators face significant risk since the vulnerability can be exploited remotely without requiring authentication, making it particularly dangerous in environments where Open vSwitch serves as a core network component for virtualized infrastructure. The flaw affects any system running Open vSwitch 2.5.0 that processes untrusted network traffic, including cloud computing platforms, virtualized network functions, and software-defined networking deployments.
The vulnerability aligns with CWE-129 and CWE-131 categories from the Common Weakness Enumeration, specifically addressing issues related to insufficient input validation and improper handling of buffer boundaries. From the MITRE ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, as attackers can bypass network access controls and potentially establish persistent access to network segments. The remote exploitation capability places this vulnerability in the high-risk category for enterprise networks, particularly affecting organizations utilizing Open vSwitch in production environments where network segmentation and access control are critical security controls. Organizations should implement immediate patch management procedures and network monitoring to detect potential exploitation attempts while considering network segmentation strategies to limit the impact of such vulnerabilities.
The remediation approach requires deployment of patched versions of Open vSwitch where the integer underflow condition has been addressed through proper input validation and boundary checking mechanisms. Security teams should also implement network intrusion detection systems capable of identifying malformed packet patterns associated with this vulnerability and consider deploying network access control lists that can filter out suspicious traffic patterns. Additionally, organizations should conduct thorough vulnerability assessments of their Open vSwitch deployments to identify any other potential buffer over-read conditions that may exist in similar network infrastructure components.