CVE-2019-8961 in FlexNet Publisher
Summary
by MITRE
A Denial of Service vulnerability related to stack exhaustion has been identified in FlexNet Publisher lmadmin.exe 11.16.2. Because the message reading function calls itself recursively given a certain condition in the received message, an unauthenticated remote attacker can repeatedly send messages of that type to cause a stack exhaustion condition.
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Analysis
by VulDB Data Team • 10/10/2020
The vulnerability described in CVE-2019-8961 represents a critical denial of service weakness within FlexNet Publisher's lmadmin.exe component version 11.16.2. This issue stems from a recursive function call pattern that occurs when processing specific message formats, creating a condition where the application's call stack becomes progressively exhausted through repeated exploitation attempts. The flaw exists in the message parsing logic that fails to properly validate incoming message structures, allowing attackers to craft malicious payloads that trigger infinite recursion.
This vulnerability operates under the weakness classification of CWE-674, which specifically addresses uncontrolled recursion in software applications. The recursive behavior manifests when lmadmin.exe receives messages that meet certain predetermined conditions, causing the function responsible for message reading to invoke itself repeatedly without proper termination conditions. The recursive calls consume stack memory resources at an exponential rate, leading to stack overflow conditions that ultimately result in application termination and complete service unavailability.
From an operational perspective, the impact of CVE-2019-8961 is severe as it allows unauthenticated remote attackers to execute denial of service attacks against affected systems. The vulnerability does not require any authentication credentials or privileged access, making it particularly dangerous in networked environments where the lmadmin.exe service is exposed to external traffic. Attackers can repeatedly send specially crafted messages to the vulnerable service, causing continuous stack exhaustion until the application crashes or becomes unresponsive, effectively denying legitimate users access to the licensing service.
The attack vector for this vulnerability follows the patterns defined in the MITRE ATT&CK framework under the technique T1499, specifically targeting network denial of service. The exploit requires minimal complexity as it only necessitates sending malformed messages to the target service, making it accessible to attackers with basic networking knowledge. The service interruption affects the entire licensing infrastructure, potentially impacting multiple applications that depend on FlexNet Publisher for software licensing management.
Mitigation strategies for CVE-2019-8961 should prioritize immediate patching of the affected FlexNet Publisher version 11.16.2 to address the recursive function handling issue. Network segmentation and firewall rules should be implemented to restrict access to the lmadmin.exe service to only trusted sources, preventing unauthorized exploitation. Additionally, implementing rate limiting and message validation mechanisms can help detect and prevent abuse of the vulnerable message parsing functionality. System monitoring should be enhanced to detect unusual stack memory consumption patterns that may indicate exploitation attempts. Organizations should also consider disabling unnecessary network exposure of the lmadmin.exe service and implementing intrusion detection systems to identify potential attack patterns targeting this specific vulnerability.