Acunetix Web Vulnerability Scanner (WVS) 4.0 Build 20060717 and earlier allows remote attackers to cause a denial of service (application crash) via multiple HTTP requests containing invalid Content-Length values.
CVSS Severity (version 2.0):
Impact Subscore: 2.9
Exploitability Subscore: 3.4
CVSS Version 2 Metrics:
Access Vector: Locally exploitable
Access Complexity: Medium
Authentication: Not required to exploit
Impact Type: Allows disruption of service
Official Statement from Acunetix Limited (01/31/2007)
Information about HTTP Sniffer:
The HTTP Sniffer is an in-build proxy server in Acunetix WVS which purpose is to analyse web traffic between a web client (browser) and a web server. By default this tool is not enabled and when enabled it accepts traffic only from the same computer running Acunetix WVS (Localhost). The default TCP port used in 8080.
This means that when the HTTP Sniffer is enabled, it is only enabled on the local network interface and no one from the network can access the HTTP Sniffer port.
How the exploit works:
The exploit works by sending a specially crafted packet containing an invalid Content-Length field in the HTTP header to the TCP port on which the HTTP Sniffer is listening. This causes the application to crash (Denial of Service). Since the HTTP Sniffer component by default is enabled only on the local network interface, it is not possible to take advantage of this exploit remotely. The user has to manually change the listening interface from within the application’s configuration to make the HTTP Sniffer available on the network for this exploit to work remotely.
Upgrade to the latest version of Acunetix WVS (v4.0 build 20060717 or later)
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