CVE-2020-37159: Parallaxis Cuckoo Clock RCE Vulnerability

CVE-2020-37159 Overview

Parallaxis Cuckoo Clock 5.0 contains a buffer overflow vulnerability that allows attackers to execute arbitrary code by overwriting memory registers in the alarm scheduling feature. Attackers can craft a malicious payload exceeding 260 bytes to overwrite EIP and EBP, enabling shellcode execution with potential remote code execution.

Critical Impact

This stack-based buffer overflow vulnerability enables arbitrary code execution through memory corruption, potentially allowing attackers to gain control of affected systems by overwriting critical processor registers.

Affected Products

• Parallaxis Cuckoo Clock 5.0

Discovery Timeline

• 2026-02-07 - CVE-2020-37159 published to NVD
• 2026-02-09 - Last updated in NVD database

Technical Details for CVE-2020-37159

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a critical memory corruption flaw where input data exceeds the allocated buffer space on the stack, overwriting adjacent memory locations including the saved return address and frame pointer.

The alarm scheduling feature in Parallaxis Cuckoo Clock 5.0 fails to properly validate the length of user-supplied input before copying it into a fixed-size stack buffer. When a payload exceeding 260 bytes is provided, the excess data overwrites the EIP (Extended Instruction Pointer) and EBP (Extended Base Pointer) registers. This allows an attacker to redirect program execution flow to arbitrary memory addresses, including attacker-controlled shellcode.

The local attack vector requires user interaction, meaning an attacker would need to convince a victim to interact with a malicious file or input. However, once triggered, the vulnerability provides high impact to confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of this vulnerability is improper bounds checking in the alarm scheduling functionality. The application allocates a fixed-size buffer on the stack but does not validate that user input fits within this allocated space before performing the copy operation. This classic buffer overflow pattern allows memory corruption when input exceeds the 260-byte boundary.

Attack Vector

The attack requires local access and user interaction. An attacker must craft a malicious payload that exceeds the 260-byte buffer limit and deliver it through the alarm scheduling feature. The payload structure typically includes padding to reach the return address offset, followed by the desired EIP value and shellcode. Upon processing, the overflow overwrites the saved return address on the stack, and when the vulnerable function returns, execution transfers to the attacker-specified address.

Technical details and proof-of-concept information are available at the Exploit-DB #48087 advisory. Additional vulnerability context can be found in the VulnCheck Advisory: Cuckoo Clock Buffer Overflow.

Detection Methods for CVE-2020-37159

Indicators of Compromise

• Unusual crashes or exceptions in the Parallaxis Cuckoo Clock application, particularly when processing alarm scheduling input
• Memory access violations or segmentation faults logged by the operating system
• Evidence of shellcode execution or unexpected child processes spawned by the application
• Anomalous input data exceeding 260 bytes in alarm-related configuration or input files

Detection Strategies

• Implement application whitelisting to detect unauthorized code execution originating from the Cuckoo Clock process
• Monitor for memory corruption indicators such as DEP (Data Execution Prevention) or ASLR violations
• Deploy endpoint detection and response (EDR) solutions capable of identifying buffer overflow exploitation patterns
• Analyze crash dumps for evidence of stack smashing or return address manipulation

Monitoring Recommendations

• Enable detailed application event logging to capture abnormal terminations and exceptions
• Configure system monitoring to alert on unexpected process behavior from CuckooClock.exe or related binaries
• Implement file integrity monitoring on application configuration files that may contain malicious payloads
• Review system logs for evidence of privilege escalation following application crashes

How to Mitigate CVE-2020-37159

Immediate Actions Required

• Discontinue use of Parallaxis Cuckoo Clock 5.0 until a patch is available or apply compensating controls
• Restrict access to the affected application to only trusted users
• Ensure operating system protections such as DEP and ASLR are enabled to increase exploitation difficulty
• Monitor affected systems for signs of compromise using the indicators described above

Patch Information

No vendor patch information is currently available for this vulnerability. Users should monitor the Softonic Author Profile for potential updates from the vendor. Consider replacing the affected software with an alternative solution that does not contain this vulnerability.

Workarounds

• Remove or disable the alarm scheduling feature if possible to eliminate the attack surface
• Implement application sandboxing to limit the impact of potential code execution
• Use network segmentation to isolate systems running the vulnerable software
• Deploy host-based intrusion prevention systems (HIPS) to block buffer overflow exploitation attempts

# Configuration example - Enable OS-level protections
# Verify DEP is enabled (Windows)
bcdedit /set nx AlwaysOn

# Check ASLR status (Windows)
reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management" /v MoveImages