Heap-based Buffer Overflow in hashcat PKZIP Hash Parser

Executive Summary

This vulnerability is a heap-based buffer overflow in the hex_to_binary function of the PKZIP hash parser in hashcat version 7.1.2. It occurs because attacker-controlled hexadecimal data from a user-supplied hash string is decoded into a fixed-size buffer without proper validation of the input length. This flaw affects several modules (17200, 17210, 17220, 17225, and 17230) when the data_type_enum is less than or equal to 1.

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Impact Analysis

An attacker exploiting this vulnerability can cause a denial of service by crashing the application or potentially execute arbitrary code on the affected system. This could lead to unauthorized control over the system running hashcat or disrupt its normal operation.

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Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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Detection Guidance

This vulnerability can be detected by identifying the presence of hashcat version 7.1.2 running on your system, especially if it is processing PKZIP hash files with modules 17200, 17210, 17220, 17225, or 17230.

To detect attempts to exploit this vulnerability, monitor for crashes or abnormal behavior in hashcat when processing PKZIP hashes, particularly those with crafted or unusually large hex data fields.

While no specific detection commands are provided, you can check the hashcat version with the command:

• hashcat --version

Additionally, monitoring logs or running hashcat in a debug mode (if available) to observe crashes or memory errors when processing PKZIP hashes may help detect exploitation attempts.

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Mitigation Strategies

Immediate mitigation steps include:

• Avoid using hashcat version 7.1.2 for processing PKZIP hashes with the affected modules (17200, 17210, 17220, 17225, 17230) until a patch or fix is applied.
• If possible, upgrade to a later version of hashcat where this heap-based buffer overflow vulnerability has been fixed.
• Restrict or monitor inputs to hashcat to prevent processing of crafted PKZIP hash files with oversized hex data fields.
• Implement system-level protections such as running hashcat with limited privileges and using memory protection mechanisms to reduce the impact of potential exploitation.

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