CVE-2018-0018 in Junos
Summary
by MITRE
On SRX Series devices during compilation of IDP policies, an attacker sending specially crafted packets may be able to bypass firewall rules, leading to information disclosure which an attacker may use to gain control of the target device or other internal devices, systems or services protected by the SRX Series device. This issue only applies to devices where IDP policies are applied to one or more rules. Customers not using IDP policies are not affected. Depending on if the IDP updates are automatic or not, as well as the interval between available updates, an attacker may have more or less success in performing reconnaissance or bypass attacks on the victim SRX Series device or protected devices. ScreenOS with IDP is not vulnerable to this issue. Affected releases are Juniper Networks Junos OS: 12.1X46 versions prior to 12.1X46-D60 on SRX; 12.3X48 versions prior to 12.3X48-D35 on SRX; 15.1X49 versions prior to 15.1X49-D60 on SRX.
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Analysis
by VulDB Data Team • 02/27/2023
This vulnerability exists within Juniper Networks SRX Series devices running specific versions of Junos OS where Intrusion Detection and Prevention (IDP) policies are actively configured and applied to firewall rules. The flaw manifests during the compilation process of IDP policies, creating a potential bypass mechanism that allows malicious actors to circumvent established firewall protections. The vulnerability specifically affects devices where IDP policies are implemented, making it critical for organizations that utilize these security features to assess their exposure. Unlike ScreenOS implementations which are not affected, this issue impacts the Junos OS platform exclusively, highlighting the importance of proper version management and patch deployment for SRX Series appliances.
The technical implementation of this vulnerability stems from improper handling of packet processing within the IDP policy compilation engine. When specially crafted packets are transmitted to the device, they can trigger a condition that allows the system to bypass normal rule evaluation procedures. This occurs because the IDP policy compilation process fails to properly validate or process certain packet characteristics that should normally be subject to firewall rule enforcement. The flaw essentially creates a pathway where packet inspection occurs outside the normal security boundaries, potentially allowing attackers to access internal systems that should be protected by the SRX device's firewall rules. This represents a significant bypass vulnerability that could enable lateral movement within networks and compromise internal assets.
The operational impact of this vulnerability extends beyond simple rule bypass to encompass potential full system compromise and information disclosure. An attacker who successfully exploits this vulnerability could gain unauthorized access to internal devices, systems, and services that are normally protected by the SRX Series firewall. The ability to perform reconnaissance and bypass attacks means that threat actors could map network topologies, identify vulnerable internal systems, and potentially escalate privileges or execute further malicious activities. The severity of this issue is compounded by the fact that the vulnerability exists only when IDP policies are actively applied, making it particularly concerning for organizations that rely heavily on these security features for network protection. The effectiveness of attacks may vary depending on whether IDP updates are automatic and how frequently they are applied, creating variable attack windows for potential exploitation.
Mitigation strategies for this vulnerability require immediate patching of affected SRX Series devices to the recommended Junos OS versions that address the IDP policy compilation flaw. Organizations should prioritize updating their SRX appliances to versions 12.1X46-D60, 12.3X48-D35, or 15.1X49-D60, depending on their current software version. Additionally, administrators should consider temporarily disabling IDP policies on affected devices until patches can be deployed, though this reduces overall security coverage. Network monitoring should be enhanced to detect unusual packet patterns that might indicate exploitation attempts, and security teams should implement continuous vulnerability assessment procedures to identify other potential weaknesses in their SRX configurations. The vulnerability aligns with CWE-284 (Improper Access Control) and can be categorized under ATT&CK technique T1071.004 (Application Layer Protocol: DNS) when used for reconnaissance purposes, and T1068 (Exploitation for Privilege Escalation) when attempting to gain control of target systems. Organizations should also review their IDP policy configurations to ensure that unnecessary or overly permissive rules are not inadvertently creating additional attack vectors.