CVE-2019-18180 in OTRS
Summary
by MITRE
Improper Check for filenames with overly long extensions in PostMaster (sending in email) or uploading files (e.g. attaching files to mails) of ((OTRS)) Community Edition and OTRS allows an remote attacker to cause an endless loop. This issue affects: OTRS AG: ((OTRS)) Community Edition 5.0.x version 5.0.38 and prior versions; 6.0.x version 6.0.23 and prior versions. OTRS AG: OTRS 7.0.x version 7.0.12 and prior versions.
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Analysis
by VulDB Data Team • 03/07/2024
This vulnerability resides in the file handling mechanisms of OTRS Community Edition and OTRS versions, specifically targeting the validation of filename extensions during email sending and file upload operations. The flaw manifests when the system processes filenames with excessively long extensions, creating a condition where the application enters an infinite loop during processing. The vulnerability is classified as a weakness in input validation and specifically relates to improper handling of file naming conventions within the email attachment and file upload modules. This type of issue falls under CWE-770, which addresses the allocation of resources without proper limits or checks, and represents a denial of service condition that can be exploited remotely. The affected versions span across multiple release lines including 5.0.x through 7.0.x, indicating a widespread impact across the OTRS product family. Attackers can leverage this vulnerability by crafting malicious filenames with excessively long extensions, causing the system to continuously process the same file validation logic without termination. This creates an endless loop that consumes system resources and can lead to complete service unavailability for legitimate users.
The operational impact of this vulnerability extends beyond simple denial of service, as it can effectively shut down email processing capabilities within the OTRS system. When an attacker sends an email with a maliciously crafted attachment or uploads a file with an overly long extension, the system's file validation routine becomes trapped in an infinite loop, consuming cpu cycles and memory resources. This creates a scenario where legitimate email processing is blocked, and the system may become unresponsive to legitimate user requests. The vulnerability is particularly dangerous in environments where OTRS serves as a critical communication platform for customer support, ticket management, or business operations, as it can disrupt essential services. From an attacker perspective, this represents a low-effort, high-impact method of causing service disruption, as it requires only the creation of a specially formatted filename rather than complex exploitation techniques. The issue can be categorized under ATT&CK technique T1499.004, which involves network disruption through resource exhaustion, and represents a classic example of a resource exhaustion attack that can be executed remotely without authentication.
Mitigation strategies for this vulnerability should focus on implementing strict input validation controls for filename extensions within the OTRS system. Organizations should immediately apply the vendor-provided patches or updates that address this specific issue, as the vulnerability has been resolved in later versions of the software. System administrators should implement additional safeguards such as setting maximum length limits for filename extensions and implementing timeout mechanisms for file processing operations. Network-level protections can include implementing rate limiting on email processing and file upload operations to prevent abuse of the vulnerability. The implementation of proper file validation routines should include checks for extension length, character validation, and resource usage monitoring to detect and prevent the exploitation of this vulnerability. Organizations should also consider implementing automated monitoring systems that can detect unusual resource consumption patterns indicative of the infinite loop condition. Regular security assessments and penetration testing should include validation of file handling capabilities to ensure that similar vulnerabilities are not present in other components of the system. The vulnerability highlights the importance of proper input validation and resource management in web applications, particularly those handling user-supplied data through email or file upload interfaces.