CVE-2017-3875 in NX-OS
Summary
by MITRE
An Access-Control Filtering Mechanisms Bypass vulnerability in certain access-control filtering mechanisms on Cisco Nexus 7000 Series Switches could allow an unauthenticated, remote attacker to bypass defined traffic configured within an access control list (ACL) on the affected system. More Information: CSCtz59354. Known Affected Releases: 5.2(4) 6.1(3)S5 6.1(3)S6 6.2(1.121)S0 7.2(1)D1(1) 7.3(0)ZN(0.161) 7.3(1)N1(0.1). Known Fixed Releases: 7.3(0)D1(1) 6.2(2) 6.1(5) 8.3(0)KMT(0.24) 8.3(0)CV(0.337) 7.3(1)N1(1) 7.3(0)ZN(0.210) 7.3(0)ZN(0.177) 7.3(0)ZD(0.194) 7.3(0)TSH(0.99) 7.3(0)SC(0.14) 7.3(0)RSP(0.7) 7.3(0)N1(1) 7.3(0)N1(0.193) 7.3(0)IZN(0.13) 7.3(0)IB(0.102) 7.3(0)GLF(0.44) 7.3(0)D1(0.178) 7.1(0)D1(0.14) 7.0(3)ITI2(1.6) 7.0(3)ISH1(2.13) 7.0(3)IFD6(0.78) 7.0(3)IFD6(0) 7.0(3)IDE6(0.12) 7.0(3)IDE6(0) 7.0(3)I2(1) 7.0(3)I2(0.315) 7.0(1)ZD(0.3) 7.0(0)ZD(0.84) 6.2(1.149)S0 6.2(0.285) 6.1(5.32)S0 6.1(4.97)S0 6.1(2.30)S0.
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability described in CVE-2017-3875 represents a critical access control filtering mechanism bypass on Cisco Nexus 7000 Series Switches, fundamentally undermining network security controls that rely on access control lists for traffic management. This issue stems from a flaw in how the switch processes and evaluates access control rules, allowing unauthorized remote attackers to circumvent configured ACLs without authentication. The vulnerability affects multiple software releases across different version lines, indicating a widespread problem within the Nexus 7000 platform's access control implementation. The technical nature of this flaw suggests an underlying issue in the packet processing pipeline where the switch fails to properly validate or enforce access control decisions, potentially enabling malicious actors to traverse network boundaries that should be protected by configured security policies.
The operational impact of this vulnerability extends beyond simple network access control bypass, as it could enable attackers to perform unauthorized data exfiltration, establish persistence within network segments, or conduct reconnaissance activities against protected resources. Network administrators who rely on ACL-based security controls for traffic filtering, segmentation, or access restriction face significant risk when this vulnerability exists in their environment. The remote nature of the exploit means that attackers do not require physical access or local network credentials to exploit the vulnerability, making it particularly dangerous in environments where network segmentation relies heavily on access control policies. This vulnerability directly impacts the CIA triad, specifically compromising confidentiality and integrity by allowing unauthorized access to network resources that should be protected by ACLs.
Cisco's response to this vulnerability included multiple fixed releases across different software version lines, indicating the severity of the issue and the need for comprehensive patching across affected platforms. The fix addresses the core problem in the access control filtering mechanism by ensuring that ACL decisions are properly enforced during packet processing. Organizations must implement immediate remediation measures including applying the appropriate software patches, monitoring network traffic for signs of exploitation, and conducting thorough security assessments of their access control configurations. The vulnerability's classification aligns with CWE-284, which describes improper access control mechanisms, and its exploitation pattern corresponds to ATT&CK techniques involving privilege escalation and lateral movement within network environments. Network security teams should also consider implementing additional monitoring controls to detect anomalous traffic patterns that might indicate exploitation attempts, as traditional ACL-based monitoring may be insufficient against this type of bypass vulnerability.