Executive Summary

CVE-2019-25570 is a denial of service (DoS) vulnerability in RealTerm Serial Terminal version 2.0.0.70 and earlier. It occurs because the application improperly handles input in the Port field.

Local attackers can crash the application by entering an excessively long string, such as a buffer of 1000 characters, into the Port input field and then clicking the open button.

This vulnerability is classified under CWE-1260, which involves improper handling of overlap between protected memory ranges, leading to a buffer overflow condition that causes the application to crash.

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Impact Analysis

This vulnerability can impact you by causing the RealTerm Serial Terminal application to crash, resulting in a denial of service.

An attacker with local access can exploit this by inputting a long string into the Port field and triggering the crash, which disrupts normal use of the application.

The impact is specifically on availability, as the application becomes unusable until restarted.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by attempting to reproduce the crash condition locally on the system running RealTerm Serial Terminal version 2.0.0.70 or earlier.'}, {'type': 'paragraph', 'content': 'Specifically, you can test by inputting an excessively long string (such as 1000 characters) into the Port input field of the RealTerm application and then clicking the open button. If the application crashes, the vulnerability is present.'}, {'type': 'paragraph', 'content': "A practical approach involves using a prepared buffer of 1000 characters (e.g., 1000 'A's) copied to the clipboard and pasted into the Port field."}, {'type': 'paragraph', 'content': "For example, you can generate the buffer using a simple Python script to create a file with 1000 'A's, then copy its content to the clipboard and paste it into the Port field:"}, {'type': 'list_item', 'content': 'Run a Python script to create a file with 1000 \'A\' characters (e.g., "PoC.txt").'}, {'type': 'list_item', 'content': 'Open the file, copy the content to the clipboard.'}, {'type': 'list_item', 'content': 'Paste the content into the Port input field of RealTerm.'}, {'type': 'list_item', 'content': 'Click the open button and observe if the application crashes.'}] [2, 1]

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Mitigation Strategies

To mitigate this vulnerability immediately, avoid entering excessively long strings into the Port input field of RealTerm Serial Terminal.

Ensure that only trusted users have local access to the system running RealTerm, as the attack requires local user interaction.

If possible, update to a version of RealTerm that addresses this vulnerability or apply any available patches from the vendor.

As a temporary workaround, restrict user permissions or usage policies to prevent pasting or entering large inputs into the Port field.

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