CVE-2019-12852 in YouTrack Server
Summary
by MITRE
An SSRF attack was possible on a JetBrains YouTrack server. The issue (1 of 2) was fixed in JetBrains YouTrack 2018.4.49168.
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Analysis
by VulDB Data Team • 06/30/2020
The vulnerability identified as CVE-2019-12852 represents a server-side request forgery flaw within JetBrains YouTrack server software that enables remote attackers to manipulate the application's behavior by tricking it into making unintended requests to internal or external systems. This type of vulnerability falls under the common weakness enumeration CWE-918, which specifically addresses server-side request forgery attacks where applications fail to properly validate and sanitize user-supplied input that influences network requests. The flaw allows attackers to bypass intended access controls and potentially gain unauthorized access to internal network resources that would normally be protected from external exposure.
The technical implementation of this vulnerability stems from insufficient validation of user-provided parameters that are subsequently used to construct HTTP requests within the YouTrack application. When users submit data that includes URLs or network addresses, the application fails to adequately sanitize or validate these inputs before using them in backend requests. This creates a pathway for malicious actors to specify arbitrary destinations for the server to connect to, potentially enabling them to access internal services, databases, or other systems that should remain isolated from external network access. The vulnerability exists specifically in the handling of network requests that are initiated by the application itself rather than being directly triggered by user input.
The operational impact of this vulnerability extends beyond simple unauthorized data access, as it can enable attackers to perform reconnaissance activities against internal network infrastructure, potentially leading to further exploitation opportunities. An attacker could leverage this vulnerability to probe internal services, identify running applications, or even attempt to exploit other vulnerabilities within the internal network that are not directly exposed to the internet. The attack vector typically involves crafting malicious input that appears legitimate to the application but contains crafted URLs or network addresses designed to target internal systems. This vulnerability is particularly dangerous in environments where YouTrack servers are deployed in corporate networks with multiple interconnected systems, as it provides a potential entry point for lateral movement within the network.
Mitigation strategies for CVE-2019-12852 should focus on implementing robust input validation and sanitization mechanisms that prevent user-supplied data from being directly used in network request construction. Organizations should ensure that all versions of JetBrains YouTrack are updated to 2018.4.49168 or later, as this release contains the necessary fixes to address the vulnerability. Additional protective measures include implementing network segmentation to limit the exposure of internal services, configuring firewall rules to restrict outbound connections from the YouTrack server, and establishing proper access controls that prevent unauthorized network access. The fix implemented by JetBrains addresses the core issue by enhancing the validation of network parameters and ensuring that only explicitly allowed URLs or destinations can be used in server-initiated requests. Security teams should also consider implementing web application firewalls and monitoring systems to detect anomalous network requests that might indicate exploitation attempts. This vulnerability aligns with tactics described in the attack pattern framework where adversaries attempt to leverage application vulnerabilities to gain access to internal resources, making it a critical concern for organizations that rely on JetBrains YouTrack for issue tracking and project management.