Executive Summary

[{'type': 'paragraph', 'content': 'Free Desktop Clock 3.0 contains a stack overflow vulnerability in the Time Zones display name input. This vulnerability allows attackers to overwrite Structured Exception Handler (SEH) registers by providing a specially crafted Unicode input.'}, {'type': 'paragraph', 'content': "When an attacker inputs a malicious string into the 'Enter display name' textbox under the Time Zones feature, it triggers an access violation and corrupts the SEH chain, which can lead to arbitrary code execution."}, {'type': 'paragraph', 'content': 'The exploit uses a technique called the Venetian Blinds technique to bypass Unicode restrictions by interleaving instructions with Unicode-compatible no-operation bytes, allowing the attacker to reconstruct and execute shellcode in memory.'}, {'type': 'paragraph', 'content': 'The shellcode dynamically locates system functions to execute commands, demonstrated by launching the calculator application (calc.exe) as proof of concept.'}] [1]

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can allow an attacker to execute arbitrary code on a vulnerable system running Free Desktop Clock 3.0 (x86).

Successful exploitation could lead to unauthorized actions such as running malicious programs, potentially compromising system integrity and confidentiality.

Since the exploit requires local access and user interaction (pasting the crafted input), the attacker needs some level of access to the system, but no special privileges are required.

The impact includes possible system compromise, data theft, or further malware installation.

Useful 0 Not Useful 0

Compliance Impact

I don't know

Useful 0 Not Useful 0

Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability is triggered by inputting a specially crafted Unicode string into the "Enter display name" textbox under the Time Zones feature of Free Desktop Clock 3.0 (x86). Detection involves monitoring for abnormal application crashes or access violations related to FreeDesktopClock.exe, specifically SEH chain corruption.'}, {'type': 'paragraph', 'content': 'Since the exploit causes an access violation at a specific address and overwrites SEH handlers, you can detect it by monitoring application crash logs or Windows Event Logs for exceptions related to FreeDesktopClock.exe.'}, {'type': 'paragraph', 'content': 'There are no direct network indicators since this is a local exploit triggered by user input. Detection commands would focus on system logs and process monitoring.'}, {'type': 'list_item', 'content': 'Use Windows Event Viewer to check for application errors related to FreeDesktopClock.exe.'}, {'type': 'list_item', 'content': "Run the following PowerShell command to filter application crash events: Get-WinEvent -FilterHashtable @{LogName='Application'; ProviderName='Application Error'} | Where-Object {$_.Message -like '*FreeDesktopClock.exe*'}"}, {'type': 'list_item', 'content': 'Monitor for access violation exceptions (e.g., 0xc0000005) in FreeDesktopClock.exe processes.'}, {'type': 'list_item', 'content': 'If possible, test the application by inputting suspicious Unicode strings into the Time Zones display name input to observe if it crashes or behaves abnormally.'}] [1]

Useful 0 Not Useful 0

Mitigation Strategies

Immediate mitigation steps include avoiding the use of the vulnerable input field with untrusted or specially crafted Unicode strings to prevent triggering the stack overflow.

Since the vulnerability is local and triggered by user input, restricting access to the Free Desktop Clock 3.0 application or uninstalling it can prevent exploitation.

Applying any available patches or updates from the software vendor is recommended once they are released.

• Do not input or allow input of untrusted Unicode strings into the Time Zones display name textbox.
• Restrict user permissions to prevent unauthorized users from running Free Desktop Clock 3.0.
• Uninstall or disable Free Desktop Clock 3.0 if it is not essential.
• Monitor for application crashes and investigate any suspicious behavior immediately.

Useful 0 Not Useful 0