CVE-2017-7678 in Spark
Summary
by MITRE
In Apache Spark before 2.2.0, it is possible for an attacker to take advantage of a user's trust in the server to trick them into visiting a link that points to a shared Spark cluster and submits data including MHTML to the Spark master, or history server. This data, which could contain a script, would then be reflected back to the user and could be evaluated and executed by MS Windows-based clients. It is not an attack on Spark itself, but on the user, who may then execute the script inadvertently when viewing elements of the Spark web UIs.
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Analysis
by VulDB Data Team • 01/01/2021
This vulnerability in Apache Spark affects versions prior to 2.2.0 and represents a sophisticated client-side attack vector that exploits user trust in web interfaces rather than direct system compromise. The flaw exists in the Spark web UI's handling of user-provided data, specifically when processing MHTML content submitted through shared cluster links. Attackers can craft malicious URLs that, when visited by unsuspecting users, trigger the submission of crafted MHTML data to the Spark master or history server. This data is then reflected back through the web interface and executed automatically by Microsoft Windows-based clients when users view the affected Spark web UI elements.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within Spark's web UI components. When users access shared Spark clusters through web interfaces, the system processes user-submitted data without adequate filtering mechanisms that would normally prevent malicious content from being executed. The MHTML format, which combines HTML with embedded resources, creates a particularly dangerous attack surface because it can contain executable scripts that Windows clients process automatically when rendering web content. This vulnerability operates at the intersection of web application security and client-side execution, making it particularly insidious as it requires no direct compromise of the Spark cluster itself.
The operational impact of this vulnerability extends beyond simple data exposure to encompass potential full system compromise through client-side exploitation. Users who visit malicious links and subsequently view the reflected MHTML content in Spark's web UI may inadvertently execute arbitrary code on their systems, potentially leading to complete system compromise. The attack requires user interaction through visiting malicious links, which aligns with social engineering tactics that can be particularly effective in enterprise environments where users trust shared cluster interfaces. This vulnerability affects Spark's history server and master web interfaces, making it applicable to both cluster management and historical data viewing scenarios.
Security mitigations for this vulnerability involve multiple layers of protection that align with established security frameworks including CWE-79 for cross-site scripting and ATT&CK techniques for client-side exploitation. The primary fix involves upgrading to Apache Spark version 2.2.0 or later, which implements proper input sanitization and output encoding for web UI elements. Organizations should also implement web application firewalls that can detect and block malicious MHTML content, establish strict access controls for shared clusters, and conduct regular security awareness training to prevent users from visiting suspicious links. Network-level protections such as content filtering and DNS-based security measures can provide additional defense in depth. The vulnerability demonstrates the importance of considering client-side attack surfaces in distributed computing environments and highlights the need for comprehensive security testing that includes user interaction scenarios.