Quester Pro Stack Overflow (CVE-2019-25319)

Overview

A critical security flaw has been identified in Domain Quester Pro version 6.02. This vulnerability allows a remote attacker to take complete control of an affected system by sending a specially crafted malicious input to the software.

Vulnerability Explained Simply

The software contains a “stack buffer overflow” in the ‘Domain Name Keywords’ input field. In simple terms, this field does not properly check the size of the data entered into it. An attacker can flood this field with too much data, which overflows its intended storage space. This overflow corrupts the program’s memory and allows the attacker to hijack the program’s error-handling mechanism (the Structured Exception Handler or SEH). By corrupting this mechanism, the attacker can redirect the software to run their own malicious code instead of crashing.

Potential Impact

The impact of this vulnerability is severe. A successful exploit gives an attacker the ability to execute any code they choose on the target machine. In the observed exploit, this code opens a “bind shell” on network port 9999. This provides the attacker with a remote command-line interface to the compromised computer, effectively granting them the same level of control as a local user. They can then:

• Install malware or ransomware.
• Steal, modify, or delete sensitive data.
• Use the system as a foothold to attack other machines on the network.
• Disrupt normal business operations.

Given the low attack complexity and that it can be exploited remotely without any user credentials, this vulnerability is rated as CRITICAL with a CVSS score of 9.8.

Remediation and Mitigation Advice

Immediate Action (Primary Remediation):

1. Upgrade or Replace: Contact the software vendor immediately to inquire about a patched version of Domain Quester Pro. If a patch is not available, strongly consider discontinuing use of this software and switching to a supported alternative.
2. Isolate Affected Systems: If the software must remain in use temporarily, ensure the host system is placed on a restricted network segment with strict firewall rules to limit access only to absolutely necessary users and systems.

Additional Mitigations:

• Network Segmentation: Implement firewall rules to block inbound connections to port 9999 (and other uncommon ports) from untrusted networks.
• Principle of Least Privilege: Run the application under a user account with the minimum permissions required for its function, not as an administrator.
• Monitoring: Deploy and monitor intrusion detection/prevention systems (IDS/IPS) for signatures related to buffer overflow exploits and unexpected outbound connections on port 9999.

All IT staff should be made aware of this advisory, and systems should be checked for any unauthorized processes or listening services on port 9999.