CVE-2008-1267 in SpeedStream 6520
Summary
by MITRE
The Siemens SpeedStream 6520 router allows remote attackers to cause a denial of service (web interface crash) via an HTTP request to basehelp_English.htm with a large integer in the Content-Length field.
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Analysis
by VulDB Data Team • 11/06/2017
The Siemens SpeedStream 6520 router presents a critical vulnerability that enables remote attackers to induce a denial of service condition through manipulation of the web interface. This flaw specifically manifests when processing HTTP requests directed toward the basehelp_English.htm resource, where an attacker can exploit the Content-Length field by injecting a large integer value. The vulnerability resides in the router's web server implementation and represents a classic buffer overflow scenario where insufficient input validation leads to system instability. The affected device operates with a web interface that fails to properly sanitize or limit the size of the Content-Length header, creating an exploitable condition that can crash the device's web server component.
From a technical perspective, this vulnerability demonstrates poor input validation practices and inadequate boundary checking within the router's HTTP processing stack. The Content-Length field in HTTP requests specifies the size of the message body, and when this value exceeds reasonable limits or contains malformed data, the router's web server fails to handle the request gracefully. The large integer value causes the system to attempt memory allocation beyond its capacity or triggers an overflow condition in the processing logic. This behavior aligns with CWE-122, which describes heap-based buffer overflow conditions, and CWE-129, which addresses insufficient validation of length fields. The vulnerability operates at the application layer and can be exploited remotely without requiring authentication, making it particularly dangerous in network environments where the router's web interface is accessible from external networks.
The operational impact of this vulnerability extends beyond simple service disruption, as it can render the entire router inaccessible through its web interface, potentially compromising network management capabilities. When the web server crashes, administrators lose the ability to configure or monitor the device through standard web-based interfaces, forcing reliance on alternative access methods such as console connections or physical access to the device. This denial of service condition can persist until the device is manually rebooted or the web server component is restarted, creating potential downtime for network operations. The vulnerability also represents a potential stepping stone for more sophisticated attacks, as attackers can use the service disruption to create conditions for further exploitation or to mask other malicious activities within the network infrastructure.
Security practitioners should implement immediate mitigations including disabling the web interface when not actively needed, restricting access to the router through firewall rules, and ensuring that only authorized personnel have access to the device's management interface. Network segmentation strategies should be employed to limit exposure of management interfaces to internal networks only, while regular firmware updates should be deployed to address known vulnerabilities. The ATT&CK framework categorizes this vulnerability under T1499.004, which describes network denial of service attacks, and T1566.001, which covers spearphishing via web applications. Organizations should also consider implementing intrusion detection systems to monitor for unusual Content-Length header values and establish incident response procedures to quickly address potential exploitation attempts. The vulnerability underscores the importance of robust input validation and proper error handling in embedded network devices, particularly those with web-based management interfaces that are frequently exposed to external network traffic.