Heap Buffer Overflow in GNU Wget

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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Executive Summary

This vulnerability exists in GNU Wget through version 1.25.0 in the html_quote_string() function located in src/convert.c. It is a heap buffer overflow caused when a remote attacker supplies a specially crafted HTML attribute containing a large number of characters that require entity encoding.

The issue arises because a signed integer counter overflows during the calculation of the output size, leading to an undersized heap allocation. When the program copies data into this undersized buffer, it causes a heap buffer overflow, potentially corrupting memory.

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Impact Analysis

This vulnerability can lead to memory corruption due to the heap buffer overflow. Such memory corruption can cause the program to crash or behave unpredictably.

In some cases, attackers might exploit this to execute arbitrary code or cause denial of service, depending on the context in which GNU Wget is used and the environment it runs in.

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Detection Guidance

This vulnerability is triggered by a remote attacker supplying a crafted HTML attribute with a large number of characters requiring entity encoding to GNU Wget version 1.25.0 or earlier.

Detection on your network or system would involve monitoring for usage of vulnerable GNU Wget versions and analyzing network traffic for suspicious HTML attributes with excessive entity-encoded characters.

Since the vulnerability is in the html_quote_string() function of GNU Wget, you can check the version of wget installed on your system with the command:

• wget --version

To detect potential exploitation attempts, you could monitor network traffic for HTTP responses containing unusually large or crafted HTML attributes that might trigger the overflow. Tools like Wireshark or network intrusion detection systems (NIDS) with custom rules could be used.

However, no specific detection commands or signatures are provided in the available resources.

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Mitigation Strategies

The immediate mitigation step is to upgrade GNU Wget to a version that includes the fix for this vulnerability, which was addressed in commit dd692d9.

If upgrading is not immediately possible, avoid using vulnerable versions of GNU Wget to fetch or process untrusted HTML content that could contain crafted attributes triggering the heap buffer overflow.

Additionally, consider applying any patches or updates provided by your operating system or distribution that incorporate the fix.

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