Executive Summary

CVE-2016-20041 is a high-severity buffer overflow vulnerability in Yasr version 0.6.9-5. It occurs when a local attacker supplies an oversized argument to the command-line parameter "-p". This causes the application to overwrite the stack with junk data, shellcode, and a return address, which can lead to the application crashing or allow the attacker to execute arbitrary code.

The vulnerability arises from improper input validation and limitation of the pathname to a restricted directory, leading to a stack-based buffer overflow. An attacker can craft a payload that overwrites the stack and hijacks the program's control flow.

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Impact Analysis

This vulnerability can have severe impacts including crashing the Yasr application, which affects availability, or allowing an attacker to execute arbitrary code with the privileges of the user running Yasr.

Since the exploit can lead to arbitrary code execution, it can result in unauthorized access, data manipulation, or local privilege escalation on the affected system.

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Detection Guidance

This vulnerability can be detected by attempting to run the Yasr application version 0.6.9-5 with an oversized argument supplied to the -p parameter. A crafted payload containing junk data, shellcode, and a return address can trigger a crash or arbitrary code execution, indicating the presence of the vulnerability.

A test command to detect the vulnerability involves executing Yasr with a payload similar to the following pattern:

• yasr -p $(python -c 'print("A"*298 + "\x31\xc0\x50\x68//sh\x68/bin\x89\xe3\x50\x53\x89\xe1\x99\xb0\x0b\xcd\x80" + "\x90"*12 + "\xd2\xf3\xff\xbf")')

If the application crashes with a segmentation fault or behaves unexpectedly, it indicates the vulnerability is present.

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Mitigation Strategies

Immediate mitigation steps include restricting local access to the Yasr application to trusted users only, as the vulnerability requires local attacker access.

Avoid running Yasr with untrusted input or scripts that supply arguments to the -p parameter.

Monitor for any unusual crashes or behavior of the Yasr application that might indicate exploitation attempts.

Apply any available patches or updates from the software maintainers that address this buffer overflow vulnerability.

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Compliance Impact

The vulnerability in Yasr 0.6.9-5 is a local buffer overflow that allows arbitrary code execution, which can lead to a compromise of confidentiality, integrity, and availability of the affected system.

Such a compromise could potentially impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and system integrity.

However, there is no specific information provided about direct effects on compliance or regulatory requirements in the available context.

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