Reachable Unwrap in relibc Causes Denial of Service

Executive Summary

This vulnerability is a reachable unwrap in the __assert_fail function located in the /assert/mod.rs file of relibc. It occurs in a specific commit (61f42d) and allows attackers to cause a Denial of Service (DoS) by using a specially crafted string.

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Impact Analysis

The vulnerability can be exploited by attackers to cause a Denial of Service (DoS), which means it can make the affected system or application unavailable or unresponsive.

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Compliance Impact

The provided information does not include any details about the 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 if any local programs on your system call the __assert_fail function with crafted strings containing the byte 0xff, which triggers a panic and causes a Denial of Service.

Since the attack vector is local, detection involves monitoring or testing local programs that use the relibc library, specifically those that invoke __assert_fail.

You can attempt to reproduce the issue by running or crafting test cases that pass strings containing the byte 0xff to functions that eventually call __assert_fail.

No specific commands are provided in the available resources, but you might use debugging or tracing tools (e.g., strace, ltrace) to monitor calls to __assert_fail or test programs with crafted inputs containing 0xff.

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Mitigation Strategies

Immediate mitigation steps include avoiding running untrusted local programs that use the vulnerable relibc version and ensuring that inputs to functions calling __assert_fail are sanitized to prevent crafted strings containing the byte 0xff.

Since the vulnerability causes a Denial of Service via a reachable unwrap, updating or patching the relibc library to a version that fixes this issue is recommended once available.

In the meantime, restrict local user access to trusted users only and monitor for crashes or panics related to __assert_fail.

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