CVE-2019-19451 in Dia
Summary
by MITRE
When GNOME Dia before 2019-11-27 is launched with a filename argument that is not a valid codepoint in the current encoding, it enters an endless loop, thus endlessly writing text to stdout. If this launch is from a thumbnailer service, this output will usually be written to disk via the system's logging facility (potentially with elevated privileges), thus filling up the disk and eventually rendering the system unusable. (The filename can be for a nonexistent file.) NOTE: this does not affect an upstream release, but affects certain Linux distribution packages with version numbers such as 0.97.3.
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Analysis
by VulDB Data Team • 03/05/2024
This vulnerability represents a critical denial of service condition in the GNOME Dia diagramming application that affects versions prior to 2019-11-27. The flaw manifests when the application is invoked with a filename argument containing invalid codepoints within the current system encoding, creating a perpetual loop that continuously outputs text to standard output. This behavior is particularly concerning because it can be triggered through thumbnailer services, which are commonly used by file managers and desktop environments to generate previews of files. The vulnerability stems from inadequate input validation and error handling mechanisms within the application's file processing logic, where malformed filename arguments cause the program to enter an infinite loop rather than gracefully handling the invalid input and terminating execution.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it can be exploited to fill system disk space through the logging facilities that capture stdout output from thumbnailer processes. When thumbnailer services execute GNOME Dia with problematic filename arguments, the continuous output is typically redirected to system log files, which may be stored on partitions with limited space or even on the root filesystem. This can lead to complete system unavailability as disk space becomes exhausted, potentially affecting critical system functions and services. The vulnerability is particularly dangerous in automated environments where thumbnail generation occurs frequently, as the denial of service can be sustained and difficult to detect. This issue specifically affects certain Linux distribution packages with version numbers such as 0.97.3, indicating that it was introduced in downstream packaging rather than being present in the upstream source code, suggesting a packaging or backporting error that created the problematic behavior.
The technical nature of this vulnerability aligns with CWE-835, which describes the weakness of an infinite loop, and can be categorized under the ATT&CK technique T1499.001 for operating system binary proxies and T1070.006 for file and directory permissions modification. The vulnerability demonstrates a classic case of improper input validation where the application fails to properly sanitize or reject malformed input before processing it, leading to uncontrolled resource consumption. From a security perspective, this represents a privilege escalation vector through indirect means, as the logging facilities often run with elevated privileges and can write to system partitions. The vulnerability can be exploited by attackers who can control or influence the filenames passed to the thumbnailer service, potentially causing system-wide disruption through disk space exhaustion. Mitigation strategies should include updating to patched versions of GNOME Dia, implementing proper input validation at the thumbnailer level, and monitoring system log file sizes to prevent unexpected disk space consumption. Organizations should also consider implementing resource limits on logging services and ensuring that thumbnail generation processes are properly sandboxed to prevent cascading failures.