CVE-2020-3405 in SD-WAN vManage
Summary
by MITRE
A vulnerability in the web UI of Cisco SD-WAN vManage Software could allow an authenticated, remote attacker to gain read and write access to information that is stored on an affected system. The vulnerability is due to improper handling of XML External Entity (XXE) entries when parsing certain XML files. An attacker could exploit this vulnerability by persuading a user to import a crafted XML file with malicious entries. A successful exploit could allow the attacker to read and write files within the affected application.
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Analysis
by VulDB Data Team • 11/04/2020
The vulnerability identified as CVE-2020-3405 resides within the web user interface of Cisco SD-WAN vManage Software, representing a critical security weakness that enables authenticated remote attackers to escalate their privileges and gain unauthorized access to sensitive data stored on the system. This flaw specifically manifests in the improper handling of XML External Entity (XXE) processing when the application parses certain XML files, creating a pathway for malicious exploitation that could compromise the integrity and confidentiality of the affected environment.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the XML parsing mechanism of the vManage software. When the application processes XML files containing external entity declarations, it fails to properly restrict or validate these references, allowing an attacker to craft malicious XML payloads that can trigger unintended system behaviors. This XXE processing flaw aligns with CWE-611, which specifically addresses improper restriction of XML external entity references, and represents a classic example of how XML parsing vulnerabilities can be exploited to gain unauthorized access to system resources. The vulnerability operates at the application layer and requires an authenticated user session to exploit, making it particularly dangerous as it leverages legitimate user privileges to perform malicious actions.
The operational impact of CVE-2020-3405 extends beyond simple data theft, as it provides attackers with both read and write capabilities within the affected application environment. Successful exploitation could enable adversaries to access sensitive configuration data, user credentials, network policies, and other critical information stored within the vManage system. The ability to perform write operations creates additional risks including potential data corruption, privilege escalation, and the possibility of establishing persistent access points within the network infrastructure. This vulnerability directly impacts the security posture of organizations relying on Cisco SD-WAN solutions, as it undermines the trust model of the application and could lead to comprehensive system compromise when combined with other attack vectors.
Security professionals should implement immediate mitigations including applying the latest security patches provided by Cisco, which address the XXE processing flaws in the vManage software. Network segmentation and access controls should be strengthened to limit the potential impact of successful exploitation, while monitoring systems should be configured to detect unusual XML file imports or access patterns. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in application security design, as outlined in the ATT&CK framework under the T1078 technique for Valid Accounts and T1566 for Phishing. Organizations should also consider implementing XML parsing restrictions and external entity disabling measures within their applications to prevent similar vulnerabilities from emerging in other components of their network infrastructure.