CVE-2018-12108 in Dropbox Lepton
Summary
by MITRE
An issue was discovered in Dropbox Lepton 1.2.1. The validateAndCompress function in validation.cc allows remote attackers to cause a denial of service (SIGFPE and application crash) via a malformed file.
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Analysis
by VulDB Data Team • 03/22/2023
The vulnerability identified as CVE-2018-12108 represents a critical denial of service flaw within Dropbox Lepton version 1.2.1, specifically targeting the validateAndCompress function located in validation.cc. This issue manifests when the application processes malformed input files, creating a condition where remote attackers can intentionally trigger system instability through carefully crafted file structures. The vulnerability operates at the core of the image compression validation logic, where insufficient input sanitization allows malicious payloads to disrupt normal application execution flow.
The technical exploitation of this vulnerability leverages integer division by zero conditions that result in SIGFPE signals, causing the application to terminate abruptly and crash. This occurs because the validateAndCompress function fails to properly validate numeric parameters within the image processing pipeline, particularly when handling compressed data structures that contain malformed headers or corrupted metadata. The flaw stems from inadequate error handling mechanisms that do not account for edge cases in input validation, allowing malformed file structures to bypass initial checks and propagate through the validation process until they encounter a division operation with zero as the denominator.
From an operational impact perspective, this vulnerability creates significant risks for systems relying on Dropbox Lepton for image processing workflows, particularly in environments where automated file handling or batch processing occurs. Remote attackers can exploit this weakness to systematically disrupt services by uploading malicious files that trigger the application crash, effectively creating a denial of service condition that impacts legitimate users and potentially enabling more sophisticated attack vectors. The vulnerability affects both the availability and reliability of the compression service, as any user with access to upload or process files can potentially cause service interruption.
Security professionals should recognize this vulnerability as aligning with CWE-369, which specifically addresses the issue of division by zero in software implementations. The flaw also corresponds to ATT&CK technique T1499.004, which covers network denial of service attacks through exploitation of application vulnerabilities. Mitigation strategies should include immediate deployment of patched versions of Dropbox Lepton, implementation of input validation layers that sanitize all file parameters before processing, and the establishment of robust error handling mechanisms that prevent arithmetic exceptions from causing application termination. Additionally, network monitoring should be enhanced to detect unusual patterns of file processing that may indicate exploitation attempts, and system administrators should consider implementing sandboxing techniques to isolate vulnerable processes from critical system resources.