Heap-based Buffer Overflow in tnef

Executive Summary

This vulnerability is a heap-based buffer overflow in the tnef utility's find_free_number() function. It occurs when numbered backups are enabled and file overwriting is disabled. An attacker can exploit it by providing a specially crafted TNEF file with many duplicate filenames, causing the numeric counter to exceed the allocated buffer and write past it. This may crash the application or potentially allow arbitrary code execution.

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Detection Guidance

To detect this vulnerability, check if the tnef utility is installed and if the --number-backups option is enabled in your system. Examine logs for crashes or unusual behavior when processing TNEF files with duplicate attachments. No specific commands are provided in the resources, but monitoring for application crashes during TNEF processing may indicate exploitation.

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Impact Analysis

The impact includes application crashes leading to Denial of Service (DoS) or potential arbitrary code execution. Exploitation requires specific non-default settings and a large malicious input, making it less likely in typical environments.

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Compliance Impact

This vulnerability primarily causes application crashes or potential arbitrary code execution, which could lead to data corruption or loss. However, the provided context does not specify direct impacts on compliance with GDPR or HIPAA. The vulnerability requires specific non-default settings and large malicious input to exploit, reducing the likelihood of real-world compliance violations.

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Mitigation Strategies

Disable the --number-backups option in tnef if enabled. Avoid processing untrusted TNEF files. Update tnef to the latest patched version if available. Since Red Hat states this does not affect supported products, focus on updating or removing vulnerable installations.

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