CVE-2019-20105 in Application Links Plugin
Summary
by MITRE
The EditApplinkServlet resource in the Atlassian Application Links plugin before version 5.4.20, from version 6.0.0 before version 6.0.12, from version 6.1.0 before version 6.1.2, from version 7.0.0 before version 7.0.1, and from version 7.1.0 before version 7.1.3 allows remote attackers who have obtained access to administrator's session to access the EditApplinkServlet resource without needing to re-authenticate to pass "WebSudo" in products that support "WebSudo" through an improper access control vulnerability.
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Analysis
by VulDB Data Team • 04/16/2024
The vulnerability described in CVE-2019-20105 represents a critical access control flaw within Atlassian's Application Links plugin ecosystem. This weakness exists in multiple version ranges spanning from 5.4.20 through 7.1.2, affecting the EditApplinkServlet resource that handles application link management operations. The vulnerability specifically targets products that implement WebSudo authentication mechanisms, which are designed to provide an additional layer of security for sensitive administrative operations by requiring re-authentication for privileged actions. The flaw allows attackers who have already compromised an administrator's session to bypass the normal authentication requirements for accessing the EditApplinkServlet endpoint, effectively undermining the WebSudo protection scheme.
The technical implementation of this vulnerability stems from improper access control checks within the servlet's authorization logic. When an administrator session is established, the system should enforce strict authentication requirements before allowing access to sensitive administrative functions such as application link configuration. However, the flaw permits attackers to pass the WebSudo parameter without proper re-authentication, creating a pathway for privilege escalation and unauthorized administrative actions. This issue directly relates to CWE-285, which addresses improper authorization in access control systems, and represents a failure in the principle of least privilege enforcement. The vulnerability operates at the application layer and can be exploited through HTTP requests that target the specific servlet endpoint, making it particularly dangerous in environments where administrative sessions are compromised through other attack vectors.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass significant security implications for organizations using Atlassian products. Attackers who have gained initial access to an administrator session can leverage this flaw to modify application links, potentially enabling them to establish connections to malicious external services, redirect traffic, or manipulate integration points within the Atlassian ecosystem. This capability can lead to data exfiltration, service disruption, or further lateral movement within the network. The vulnerability also undermines the trust model of Atlassian products, as it allows attackers to bypass the intended security controls that protect against unauthorized administrative modifications. Organizations may experience compromised integrity of their application link configurations, potentially affecting multiple integrated services and applications that depend on proper link management.
Mitigation strategies for this vulnerability require immediate patching of affected Atlassian products to versions 5.4.20, 6.0.12, 6.1.2, 7.0.1, and 7.1.3 respectively, which contain the necessary access control fixes. Administrators should also implement additional monitoring of the EditApplinkServlet endpoint to detect unauthorized access attempts and review application link configurations regularly. The implementation of network segmentation and privileged access management controls can help limit the potential damage from session compromise. Organizations should also consider implementing WebSudo enforcement policies that require re-authentication for all administrative functions and establish baseline security configurations that disable unnecessary application link features. This vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate administrative access, highlighting the importance of protecting administrative sessions and enforcing proper access controls even within trusted administrative contexts.