CVE-2017-2787 in PopUp Printer Client
Summary
by MITRE
A buffer overflows 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 potential 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 identified as CVE-2017-2787 represents a critical heap-based buffer overflow flaw within the psnotifyd component of the Pharos PopUp printer client version 9.0. This application serves as a network notification service that operates continuously on victim systems, making it an attractive target for remote exploitation. The flaw stems from inadequate input validation mechanisms within the packet processing functionality, specifically when handling malformed network packets sent to the listening service. The psnotifyd application runs with elevated privileges, typically possessing root access on the target system, which significantly amplifies the potential impact of this vulnerability.
The technical implementation of this buffer overflow occurs when the application receives specially crafted network packets that exceed the allocated buffer space in memory. This heap-based overflow allows an attacker to overwrite adjacent memory locations, potentially corrupting critical program data structures or executable code. The vulnerability is particularly dangerous because the psnotifyd service operates continuously without requiring any user interaction, meaning that exploitation can occur automatically when a malicious packet is received. The application's persistent listening nature and root privileges create a perfect storm for remote code execution, as successful exploitation would grant attackers complete control over the affected system.
From an operational perspective, this vulnerability presents a severe risk to organizations relying on Pharos PopUp printer clients, particularly in environments where network segmentation is insufficient or where the client applications are deployed across multiple network zones. The lack of user interaction requirements means that attackers can exploit this vulnerability remotely without needing to compromise user credentials or gain physical access to the target system. Network-based attacks can be launched from any location with access to the target network, making this vulnerability particularly concerning for enterprise environments where printer clients are often deployed across various network segments. The continuous listening nature of the service means that there is no window of opportunity for exploitation, as the service is always available to process incoming packets.
Security mitigations for this vulnerability should focus on immediate patching of the Pharos PopUp printer client to version 9.1 or later, which contains the necessary fixes for the buffer overflow condition. Organizations should also implement network segmentation strategies to limit access to printer services, particularly by restricting network access to the psnotifyd listening ports from untrusted networks. The deployment of network intrusion detection systems can help identify and block malicious packet patterns associated with this specific vulnerability. Additionally, system administrators should consider temporarily disabling the psnotifyd service if immediate patching is not feasible, though this may impact legitimate printer notification functionality. According to CWE standards, this vulnerability maps to CWE-121, heap-based buffer overflow, while ATT&CK framework categorizes this as a remote code execution technique that leverages persistent services with elevated privileges. The vulnerability also aligns with ATT&CK technique T1059 for remote code execution and T1068 for local privilege escalation, as the root privileges inherent to the service allow for complete system compromise upon successful exploitation.