CVE-2021-37253 in Web
Summary
by MITRE • 12/06/2021
M-Files Web before 20.10.9524.1 allows a denial of service via overlapping ranges (in HTTP requests with crafted Range or Request-Range headers).
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Analysis
by VulDB Data Team • 08/04/2024
The vulnerability identified as CVE-2021-37253 affects M-Files Web versions prior to 20.10.9524.1 and represents a denial of service weakness that exploits overlapping ranges within HTTP requests. This flaw specifically targets the handling of Range and Request-Range headers, which are standard HTTP mechanisms used for requesting specific portions of a resource. The vulnerability stems from insufficient validation of these headers, allowing malicious actors to craft HTTP requests that contain overlapping byte ranges that the application cannot properly process.
The technical implementation of this vulnerability involves the application's failure to properly sanitize or validate range specifications in HTTP requests. When a client sends a request containing overlapping ranges in either the Range or Request-Range headers, the M-Files Web server processes these requests without adequate bounds checking or range normalization. This processing error can cause the server to enter an infinite loop or consume excessive computational resources while attempting to resolve the overlapping ranges, ultimately leading to a denial of service condition that renders the application unavailable to legitimate users.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on M-Files Web for document management and collaboration services. The denial of service condition can disrupt business operations by making the document management system inaccessible to authorized users, potentially affecting productivity and access to critical business documents. The vulnerability is particularly concerning because it can be exploited with relatively simple HTTP requests that do not require authentication or specialized tools, making it accessible to a wide range of threat actors.
The vulnerability aligns with CWE-129, which addresses improper validation of input ranges, and relates to ATT&CK technique T1499.004 for network denial of service attacks. Organizations should implement immediate mitigations including upgrading to M-Files Web version 20.10.9524.1 or later, which contains the necessary patches to properly validate range headers. Additional protective measures include implementing rate limiting on HTTP requests, deploying web application firewalls that can detect and block malformed range headers, and configuring servers to reject requests with overlapping ranges. Network monitoring should be enhanced to detect unusual patterns of range-based requests that may indicate exploitation attempts. The fix addresses the root cause by implementing proper range validation and normalization logic that ensures overlapping ranges are either rejected or properly merged before processing, thereby preventing the resource exhaustion that leads to denial of service conditions.