CVE-2024-29209 in Phish Alert Button for Outlook
Summary
by MITRE • 05/07/2024
A medium severity vulnerability has been identified in the update mechanism of the Phish Alert Button for Outlook, which could allow an attacker to remotely execute arbitrary code on the host machine. The vulnerability arises from the application's failure to securely verify the authenticity and integrity of the update server.
The application periodically checks for updates by querying a specific URL. However, this process does not enforce strict SSL/TLS verification, nor does it validate the digital signature of the received update files. An attacker with the capability to perform DNS spoofing can exploit this weakness. By manipulating DNS responses, the attacker can redirect the application's update requests to a malicious server under their control.
Once the application queries the spoofed update URL, the malicious server can respond with a crafted update package. Since the application fails to properly verify the authenticity of the update file, it will accept and execute the package, leading to arbitrary code execution on the host machine.
Impact: Successful exploitation of this vulnerability allows an attacker to execute code with elevated privileges, potentially leading to data theft, installation of further malware, or other malicious activities on the host system.
Affected Products: Phish Alert Button (PAB) for Outlook versions 1.10.0-1.10.11 Second Chance Client versions 2.0.0-2.0.9 PIQ Client versions 1.0.0-1.0.15
Remediation: Automated updates will be pushed to address this issue. Users of affected versions should verify the latest version is applied and, if not, apply the latest updates provided by KnowBe4, which addresses this vulnerability by implementing proper SSL/TLS checks of the update server. It is also recommended to ensure DNS settings are secure to prevent DNS spoofing attacks.
Workarounds: Use secure corporate networks or VPN services to secure network communications, which can help mitigate the risk of DNS spoofing.
Credits: This vulnerability was discovered by Ceri Coburn at Pen Test Partners, who reported it responsibly to the vendor.
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Analysis
by VulDB Data Team • 08/08/2024
The vulnerability described in CVE-2024-29209 represents a critical security flaw in the update mechanism of Phish Alert Button for Outlook and related applications, classified as medium severity but with significant operational implications. This vulnerability stems from inadequate security controls during the software update process, specifically targeting the application's failure to properly validate update authenticity and integrity. The flaw manifests when the application performs periodic update checks by querying a designated URL, yet lacks robust SSL/TLS certificate validation and digital signature verification of downloaded update files. This design weakness creates an exploitable attack vector that aligns with CWE-295, which addresses "Improper Certificate Validation" and specifically covers scenarios where applications fail to properly verify SSL/TLS certificates. The vulnerability directly maps to ATT&CK technique T1068, "Exploitation for Privilege Escalation," as successful exploitation leads to code execution with elevated privileges.
The operational impact of this vulnerability extends beyond simple code execution, creating a comprehensive attack surface that enables sophisticated malicious activities. An attacker capable of performing DNS spoofing can manipulate the application's update requests to redirect traffic to a malicious server under their control, effectively executing a man-in-the-middle attack against the update process. The application's trust model fails completely when processing update responses, as it accepts and executes packages without proper authentication mechanisms. This flaw represents a fundamental breakdown in the principle of least privilege and secure update validation, allowing attackers to install backdoors, steal sensitive data, or deploy additional malware with system-level access. The vulnerability affects multiple product lines including PAB for Outlook versions 1.10.0-1.10.11, Second Chance Client versions 2.0.0-2.0.9, and PIQ Client versions 1.0.0-1.0.15, indicating a systemic issue across the software ecosystem. The exploitation pathway follows ATT&CK tactic T1190, "Exploit Public-Facing Application," through DNS manipulation, combined with T1059, "Command and Scripting Interpreter," as the malicious update package executes arbitrary code.
The remediation approach focuses on implementing proper SSL/TLS verification and digital signature validation mechanisms, which directly addresses the root cause of the vulnerability. The vendor's response includes automated updates that enforce secure certificate validation, a critical security control that aligns with NIST SP 800-53 security controls for secure system development. The recommended fixes involve strengthening the update verification process to ensure that all downloaded packages undergo cryptographic validation before execution. Additionally, the security community's guidance emphasizes DNS security measures as a complementary defense mechanism, reflecting the broader threat landscape where DNS-based attacks represent a common initial compromise vector. Organizations should implement DNS security solutions such as DNSSEC, DNS over HTTPS, or DNS over TLS to prevent the type of DNS spoofing that enables this vulnerability. The vulnerability's discovery and responsible disclosure by Ceri Coburn at Pen Test Partners demonstrates the importance of coordinated vulnerability disclosure practices and highlights how security researchers play a crucial role in identifying and mitigating such threats before widespread exploitation occurs. The remediation process also requires verification of update integrity through proper cryptographic signatures, which provides defense-in-depth against tampered update packages and aligns with security frameworks like ISO 27001 and CIS Controls that emphasize secure software development practices and update management protocols.