CVE-2011-2007 in Host Integration Server
Summary
by MITRE
Microsoft Host Integration Server (HIS) 2004 SP1, 2006 SP1, 2009, and 2010 allows remote attackers to cause a denial of service (SNA Server service outage) via crafted TCP or UDP traffic, aka "Endless Loop DoS in snabase.exe Vulnerability."
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Analysis
by VulDB Data Team • 03/15/2025
The CVE-2011-2007 vulnerability represents a critical denial of service flaw within Microsoft Host Integration Server implementations that affected multiple versions including 2004 SP1, 2006 SP1, 2009, and 2010. This vulnerability specifically targets the SNA Server service component responsible for managing IBM SNA (Systems Network Architecture) communications within enterprise environments. The flaw manifests through a design weakness in the snabase.exe process that handles network protocol processing, creating a condition where malformed or specially crafted TCP and UDP traffic can trigger an infinite loop within the service. This vulnerability operates at the network protocol level and represents a classic example of a resource exhaustion attack that can bring down critical enterprise integration services.
The technical exploitation of this vulnerability occurs when an attacker sends malformed packets to the SNA Server service listening on standard network ports. The snabase.exe process fails to properly validate incoming network traffic, particularly around session establishment and protocol handling routines. When processing these crafted packets, the service enters an infinite loop within its packet parsing logic, causing continuous CPU utilization and ultimately leading to service unavailability. This behavior aligns with CWE-835, which describes the weakness of an infinite loop, and demonstrates how improper input validation can create conditions for denial of service attacks. The vulnerability specifically impacts the SNA Server service which is fundamental to mainframe connectivity in enterprise environments, making it particularly dangerous for organizations relying on legacy system integration.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire enterprise integration infrastructures. Organizations utilizing Microsoft Host Integration Server for connecting legacy mainframe systems to modern networks face significant business continuity risks when this vulnerability is exploited. The service outage affects not just the SNA Server itself but can cascade through integrated systems that depend on proper mainframe connectivity for critical business processes. Attackers can cause sustained disruption with minimal resources, making this vulnerability particularly attractive for malicious actors seeking to impact enterprise operations. The attack surface includes any network endpoint where the HIS SNA Server service is exposed, including DMZ boundaries and internal network segments where mainframe integration services operate.
Mitigation strategies for CVE-2011-2007 should focus on both immediate defensive measures and long-term architectural improvements. Microsoft released security patches addressing this vulnerability through regular updates, but organizations should also implement network segmentation to limit exposure of the SNA Server service to untrusted networks. Network access control lists and firewalls should be configured to restrict access to the specific ports used by the SNA Server service, typically including TCP ports 2000-2002 and UDP ports 2000-2002. Additionally, implementing intrusion detection systems that can identify malformed SNA protocol traffic patterns provides early warning capabilities. Organizations should also consider implementing redundant integration services and establishing incident response procedures for handling service outages. The vulnerability demonstrates the importance of proper input validation and defensive programming practices, aligning with ATT&CK technique T1499.002 which covers network denial of service attacks. Regular vulnerability assessments and security monitoring of integration server components remain essential for detecting similar weaknesses in enterprise infrastructure.