CVE-2020-1637 in Junos
Summary
by MITRE
A vulnerability in Juniper Networks SRX Series device configured as a Junos OS Enforcer device may allow a user to access network resources that are not permitted by a UAC policy. This issue might occur when the IP address range configured in the Infranet Controller (IC) is configured as an IP address range instead of an IP address/netmask. See the Workaround section for more detail. The Junos OS Enforcer CLI settings are disabled by default. This issue affects Juniper Networks Junos OS on SRX Series: 12.3X48 versions prior to 12.3X48-D100; 15.1X49 versions prior to 15.1X49-D210; 17.3 versions prior to 17.3R2-S5, 17.3R3-S8; 17.4 versions prior to 17.4R2-S9, 17.4R3-S1; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R2-S7, 18.2R3-S3; 18.3 versions prior to 18.3R1-S7, 18.3R3-S2; 18.4 versions prior to 18.4R1-S6, 18.4R2-S4, 18.4R3-S1; 19.1 versions prior to 19.1R1-S4, 19.1R2-S1, 19.1R3; 19.2 versions prior to 19.2R1-S3, 19.2R2; 19.3 versions prior to 19.3R2-S1, 19.3R3; 19.4 versions prior to 19.4R1-S1, 19.4R2.
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Analysis
by VulDB Data Team • 05/17/2024
The vulnerability identified as CVE-2020-1637 affects Juniper Networks SRX Series devices operating as Junos OS Enforcer devices, representing a significant authorization bypass flaw that undermines the intended security controls of Unified Access Control (UAC) policies. This issue stems from a configuration misalignment within the Infranet Controller (IC) component where IP address ranges are incorrectly specified as individual IP addresses rather than proper CIDR notation with netmask values. The fundamental flaw occurs at the policy enforcement level where the system fails to properly validate and process IP address range configurations, creating a pathway for unauthorized network access that circumvents established security boundaries. The vulnerability is particularly concerning because it operates at the network infrastructure level where access control decisions are made, potentially allowing malicious actors to traverse network segments they should not be permitted to access based on their assigned UAC policies.
The technical implementation of this vulnerability involves a specific configuration error within the Junos OS Enforcer functionality where the system processes IP address ranges differently when they are defined without proper netmask notation. When administrators configure IP address ranges in the Infranet Controller using IP address format instead of IP address/netmask format, the underlying enforcement mechanism fails to properly interpret these ranges, leading to incorrect access control decisions. This misinterpretation results in a privilege escalation scenario where users can potentially access network resources that fall within the improperly configured IP ranges, effectively bypassing the intended security boundaries established by UAC policies. The vulnerability manifests specifically when the system attempts to validate access requests against these incorrectly formatted IP ranges, creating a gap in the access control enforcement mechanism.
The operational impact of CVE-2020-1637 extends beyond simple unauthorized access to encompass potential lateral movement within network environments and compromise of sensitive resources. Attackers exploiting this vulnerability could gain access to network segments that should be restricted to authorized personnel only, potentially leading to data exfiltration, system compromise, or further network infiltration. The default disablement of Junos OS Enforcer CLI settings provides some mitigation but does not eliminate the core vulnerability in the configuration processing logic. Organizations using affected SRX Series devices may experience unauthorized access to internal network resources, potentially exposing critical infrastructure to malicious actors who can leverage the improperly configured IP ranges to bypass security controls established by the UAC policy framework. This vulnerability directly impacts the integrity of network access control mechanisms and undermines the security posture of organizations relying on Juniper SRX devices for network protection.
Mitigation strategies for CVE-2020-1637 require immediate attention to configuration practices within the Infranet Controller component of Junos OS Enforcer devices. Organizations must ensure that all IP address ranges configured in the IC are properly formatted using IP address/netmask notation rather than individual IP addresses to prevent the vulnerability from being exploited. The recommended approach involves reviewing and correcting all existing IP range configurations to comply with proper CIDR notation standards, while also implementing strict configuration management controls to prevent future occurrences. Additionally, administrators should upgrade to the patched versions of Junos OS specified in the affected release lists, as these updates contain fixes that address the IP range processing logic and prevent the improper interpretation of IP address configurations. The workaround procedures outlined in Juniper's security advisories should be implemented immediately to provide temporary protection while long-term remediation efforts are underway. This vulnerability aligns with CWE-284 (Improper Access Control) and may be leveraged through techniques consistent with ATT&CK tactics such as privilege escalation and lateral movement, making it a critical security concern for network infrastructure environments.