CVE-2020-15352 in Pulse Connect Secure
Summary
by MITRE • 10/27/2020
An XML external entity (XXE) vulnerability in Pulse Connect Secure (PCS) before 9.1R9 and Pulse Policy Secure (PPS) before 9.1R9 allows remote authenticated admins to conduct server-side request forgery (SSRF) attacks via a crafted DTD in an XML request.
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Analysis
by VulDB Data Team • 11/27/2020
The vulnerability CVE-2020-15352 represents a critical XML external entity (XXE) flaw affecting Pulse Connect Secure (PCS) and Pulse Policy Secure (PPS) appliances prior to version 9.1R9. This security weakness stems from inadequate input validation within the XML processing mechanisms of these network security appliances, which are commonly deployed for secure remote access and policy enforcement. The vulnerability specifically manifests when the affected systems process XML requests containing maliciously crafted Document Type Definitions (DTDs), enabling attackers to exploit the underlying XML parser's handling of external entities.
The technical exploitation of this XXE vulnerability enables authenticated administrative users to perform server-side request forgery attacks through carefully constructed XML payloads. When the vulnerable systems process these malicious requests, the XML parser attempts to resolve external entity references contained within the DTD, potentially allowing attackers to make arbitrary network requests from the server's perspective. This capability enables attackers to bypass network segmentation controls and access internal resources that would normally be protected from external access. The vulnerability operates at the application layer and can be leveraged to perform reconnaissance, access internal services, or even exfiltrate data from behind network firewalls, making it particularly dangerous in enterprise environments where these appliances serve as critical security gateways.
From an operational impact perspective, this vulnerability compromises the integrity and confidentiality of network security infrastructure by allowing authenticated administrators to escalate their privileges and access unauthorized resources. The attack surface extends beyond simple data exfiltration to include potential lateral movement within networks, as the SSRF capabilities can be used to probe internal systems and services that are normally protected from external network access. Organizations using these appliances face significant risk of unauthorized access to sensitive internal resources, including databases, internal web applications, and other network services that may contain critical business data or system credentials.
Security mitigations for CVE-2020-15352 primarily involve applying the vendor-provided patches and updates to Pulse Connect Secure and Pulse Policy Secure appliances, specifically versions 9.1R9 and later. Organizations should also implement network segmentation and firewall rules to limit the ability of authenticated users to make arbitrary network requests, while enabling XML parser configuration to disable external entity resolution and DTD processing. The vulnerability aligns with CWE-611 (Improper Restriction of XML External Entity Reference) and can be categorized under ATT&CK technique T1071.004 (Application Layer Protocol: DNS) and T1566.002 (Phishing: Spearphishing Attachments) when considering the potential for initial compromise through malicious attachments. Additionally, implementing proper input validation and sanitization measures, conducting regular security assessments, and monitoring for unusual network activity can help detect and prevent exploitation attempts. Organizations should also consider implementing network access controls and privilege management to limit the scope of potential damage should exploitation occur, as the vulnerability specifically targets authenticated administrative accounts.