CVE-2017-9046 in Mail
Summary
by MITRE
winpm-32.exe in Pegasus Mail (aka Pmail) v4.72 build 572 allows code execution via a crafted ssgp.dll file that must be installed locally. For example, if ssgp.dll is on the desktop and executes arbitrary code in the DllMain function, then clicking on a mailto: link on a remote web page triggers the attack.
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Analysis
by VulDB Data Team • 07/02/2020
The vulnerability CVE-2017-9046 represents a critical code execution flaw in Pegasus Mail version 4.72 build 572 specifically affecting the winpm-32.exe component. This issue stems from improper handling of dynamically loaded libraries within the email client's architecture, creating a persistent security weakness that can be exploited through social engineering tactics. The vulnerability operates through a carefully crafted ssgp.dll file that must be locally installed on the target system, making it a local privilege escalation vector that requires initial compromise through user interaction or system infiltration.
The technical flaw manifests in the DllMain function of the malicious ssgp.dll file, which executes arbitrary code when loaded by the winpm-32.exe process. This represents a classic dynamic link library injection attack pattern where the malicious payload is loaded into the legitimate email client process space, allowing the attacker to execute commands with the privileges of the target user. The vulnerability is classified under CWE-427 Uncontrolled Search Path Element, as the application fails to properly validate or sanitize the search path for dynamically loaded libraries, and it aligns with CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer, as the malicious code can execute arbitrary instructions within the process memory space.
The operational impact of this vulnerability is significant as it enables attackers to execute arbitrary code on compromised systems without requiring administrative privileges, provided the malicious ssgp.dll file is present on the local system. The attack vector described in the CVE involves a sophisticated social engineering component where users are tricked into clicking mailto: links on malicious web pages, which then trigger the loading of the malicious DLL. This creates a persistent threat model where a single user interaction can lead to complete system compromise, potentially allowing attackers to establish backdoors, exfiltrate sensitive data, or deploy additional malware. The vulnerability's exploitation is particularly concerning because it leverages legitimate email client functionality while remaining隐蔽 from standard network-based intrusion detection systems.
The attack chain begins with the initial compromise of the target system through delivery of the malicious ssgp.dll file, which could occur through various means including phishing emails, compromised websites, or direct malicious software distribution. Once installed, the DLL remains dormant until triggered by the winpm-32.exe process, typically when users interact with email links or open email messages containing the malicious payload. This vulnerability also aligns with ATT&CK technique T1059 Command and Scripting Interpreter, as it allows execution of malicious code through legitimate system processes, and T1068 Exploitation for Privilege Escalation, as it provides a method for executing code with elevated privileges. Organizations should implement strict file access controls, regularly audit system directories for unauthorized DLL files, and deploy application whitelisting solutions to prevent the execution of untrusted code. The vulnerability demonstrates the importance of secure coding practices and proper input validation, particularly when dealing with dynamic library loading mechanisms in email client applications.