CVE-2017-2785 in PopUp Printer Client
Summary
by MITRE
An exploitable buffer overflow exists in the psnotifyd application of the Pharos PopUp printer client version 9.0. A specially crafted packet can be sent to the victim's computer and can lead to a heap based buffer overflow resulting in remote code execution. This client is always listening, has root privileges, and requires no user interaction to exploit.
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Analysis
by VulDB Data Team • 09/05/2020
The vulnerability described in CVE-2017-2785 represents a critical heap-based buffer overflow within the psnotifyd component of the Pharos PopUp printer client version 9.0. This flaw exists in a network service that operates continuously and listens for incoming connections, making it particularly dangerous as it can be exploited remotely without any user interaction. The psnotifyd application runs with elevated privileges, specifically root access, which significantly amplifies the potential impact of this vulnerability. The attack vector involves sending a specially crafted packet to the victim's computer, where the buffer overflow occurs in the heap memory region, allowing an attacker to potentially execute arbitrary code with system-level privileges.
This vulnerability falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions, though the heap-based nature of this particular flaw makes it more complex to exploit and analyze. The continuous listening nature of the service creates an ideal environment for remote exploitation, as the attacker does not need to wait for user interaction or specific conditions to trigger the vulnerability. The service's requirement for no user interaction means that exploitation can occur automatically upon receipt of the malicious packet, making this a particularly concerning security flaw in networked environments where printer clients are deployed. The heap-based nature of the buffer overflow also means that traditional stack-based exploitation techniques may not apply, requiring more sophisticated approaches to achieve remote code execution.
The operational impact of this vulnerability extends beyond simple remote code execution, as the service runs with root privileges and is always active, creating persistent access points for attackers. The continuous listening nature means that the vulnerability remains exploitable over extended periods, and the service's privileged execution context allows for complete system compromise rather than just user-level access. Network administrators face significant challenges in mitigating this vulnerability as it requires either patching the application, disabling the service, or implementing network-level restrictions to prevent unauthorized access to the printer client service. The vulnerability demonstrates a critical flaw in the security design of networked printing systems, where services that require elevated privileges are exposed to unauthenticated network connections.
Mitigation strategies for CVE-2017-2785 should focus on immediate patching of the Pharos PopUp printer client to version 9.1 or later, which contains the necessary security fixes to address the heap-based buffer overflow. Network segmentation and firewall rules should be implemented to restrict access to the printer client service ports, preventing unauthorized network access to the vulnerable application. System administrators should also consider disabling the psnotifyd service if it is not required for operations, as this eliminates the attack surface entirely. Additionally, monitoring network traffic for suspicious packets targeting the printer client service can help detect potential exploitation attempts. The vulnerability highlights the importance of proper input validation and memory management in network services, particularly those that operate with elevated privileges. Organizations should also implement regular vulnerability assessments and penetration testing to identify similar flaws in other networked applications and services, ensuring comprehensive security coverage across their infrastructure. The ATT&CK framework categorizes this vulnerability under T1059 for command and scripting interpreter, as successful exploitation would allow attackers to execute arbitrary code and establish persistent access to target systems.