CVE-2015-0756 in Wireless LAN Controller
Summary
by MITRE
Cisco Wireless LAN Controller (WLC) devices with software 7.4(1.1) allow remote attackers to cause a denial of service (wireless-networking outage) via crafted TCP traffic on the local network, aka Bug ID CSCug67104.
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Analysis
by VulDB Data Team • 08/03/2017
Cisco Wireless LAN Controller devices running software version 7.4(1.1) contain a critical vulnerability that enables remote attackers to trigger a denial of service condition affecting wireless networking operations. This vulnerability specifically manifests through crafted TCP traffic transmitted across the local network, exploiting a flaw in the device's network processing mechanisms that results in complete wireless service disruption. The vulnerability affects the controller's ability to maintain stable wireless connectivity for connected devices, effectively creating a network outage that can impact enterprise wireless infrastructure.
The technical flaw resides in the Wireless LAN Controller's handling of TCP packets within its local network interface processing. When maliciously constructed TCP traffic reaches the device, it triggers an unexpected behavior in the controller's packet processing engine that leads to system instability and subsequent service termination. This occurs due to improper input validation and memory management within the TCP stack implementation, causing the wireless networking functions to crash or become unresponsive. The vulnerability operates at the network protocol level, making it particularly dangerous as it requires minimal privileges to exploit and can be initiated from within the local network segment.
The operational impact of this vulnerability extends beyond simple service interruption, as it can compromise enterprise wireless infrastructure reliability and business continuity. Organizations relying on Cisco WLC devices for wireless network management face potential downtime that can affect productivity, communication systems, and critical business operations. The vulnerability's remote exploitability from the local network means that attackers who gain access to the local network segment can immediately disrupt wireless services without requiring additional authentication or network access privileges. This makes the attack surface particularly concerning for enterprise environments where local network access may be more easily obtained than external network access.
Mitigation strategies should focus on immediate software updates to address the underlying TCP processing flaw in the Cisco WLC software. Network administrators should prioritize applying the official Cisco security patches and updates to all affected devices, ensuring that software versions are upgraded to prevent exploitation. Additionally, implementing network segmentation and access controls to limit local network access can reduce the attack surface for potential exploitation. Monitoring network traffic for unusual TCP patterns and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability aligns with CWE-129, which addresses improper input validation, and corresponds to ATT&CK technique T1498, representing denial of service attacks targeting network infrastructure components. Organizations should also consider implementing redundant wireless infrastructure and backup systems to maintain operational continuity during potential exploitation events.