Executive Summary

CVE-2019-25627 is a local buffer overflow vulnerability in FlexHEX version 2.71, specifically in the Stream Name field.

Local attackers can exploit this flaw by crafting a malicious text file containing carefully aligned shellcode and structured exception handler (SEH) chain pointers. When the attacker pastes this content into the Stream Name dialog, it triggers an SEH overflow.

This overflow allows the attacker to execute arbitrary code on the affected system, such as running commands like calc.exe.

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Impact Analysis

[{'type': 'paragraph', 'content': 'This vulnerability allows local attackers to execute arbitrary code with the privileges of the user running FlexHEX.'}, {'type': 'list_item', 'content': 'Attackers can run unauthorized commands or programs on the affected system.'}, {'type': 'list_item', 'content': "It can lead to local privilege escalation or compromise of the system's integrity."}, {'type': 'list_item', 'content': 'Because the exploit involves executing shellcode via a buffer overflow, it can be used to bypass normal security controls.'}] [1, 3]

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability is a local buffer overflow in the Stream Name field of FlexHEX 2.71, triggered by pasting specially crafted data into the Stream Name dialog. Detection involves identifying if FlexHEX 2.71 or earlier is installed and if malicious input has been used in the Stream Name field.'}, {'type': 'paragraph', 'content': 'Since the exploit requires local interaction (pasting crafted data into the Stream Name dialog), network detection is not applicable.'}, {'type': 'paragraph', 'content': 'To detect potential exploitation attempts or presence of the vulnerable software, you can:'}, {'type': 'list_item', 'content': 'Check if FlexHEX 2.71 or earlier is installed on your system.'}, {'type': 'list_item', 'content': 'Monitor process creation for suspicious commands like calc.exe launched from FlexHEX.'}, {'type': 'list_item', 'content': 'Look for unusual clipboard activity or pasting actions into FlexHEX.'}, {'type': 'paragraph', 'content': 'No specific detection commands are provided in the resources. However, you can use Windows commands to check for FlexHEX installation and running processes, for example:'}, {'type': 'list_item', 'content': 'To check if FlexHEX is installed: `wmic product where "name like \'%FlexHEX%\'" get name,version`'}, {'type': 'list_item', 'content': 'To monitor running FlexHEX processes: `tasklist /FI "IMAGENAME eq flexhex.exe"`'}, {'type': 'list_item', 'content': 'To check for suspicious calc.exe processes launched unexpectedly: `tasklist /FI "IMAGENAME eq calc.exe"`'}] [1, 3]

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Mitigation Strategies

Immediate mitigation steps include:

• Avoid using FlexHEX version 2.71 or earlier until a patch or update is available.
• Do not paste untrusted or suspicious data into the Stream Name field of FlexHEX.
• Restrict local user access to FlexHEX if possible, especially for untrusted users.
• Monitor for unusual behavior such as unexpected execution of commands like calc.exe triggered by FlexHEX.

Since this is a local vulnerability requiring user interaction, preventing untrusted users from running FlexHEX or pasting malicious input is critical.

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