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Cisco Web Security Appliance Connection Denial of Service Vulnerability

cisco-sa-20160518-wsa4 · High · Published · Updated

A vulnerability in Cisco AsyncOS for the Cisco Web Security Appliance (WSA) when the software handles a specific HTTP response code could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an appliance because the appliance runs out of system memory. The vulnerability occurs because the software does not free client and server connection memory and system file descriptors when a certain HTTP response code is received in the HTTP request. An attacker could exploit this vulnerability by sending a crafted HTTP request to the affected device. An exploit could allow the attacker to cause a DoS condition because the appliance runs out of system memory. When this happens, the device can no longer accept new incoming connection requests. Cisco has released software updates that address this vulnerability. A workaround that addresses this vulnerability is also available.   This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160518-wsa4

Cisco advisory ·CSAF JSON

Workarounds

If the results of using the status detail command in the Cisco WSA CLI indicate an accumulation of TCP connections, as described in the "Indicators of Compromise" section, use the diagnostic -> PROXY -> KICK hidden command to restart the proxy process and reclaim memory.

CVEsCVE-2016-1383
Cisco Bug IDsCSCur28305
CVSS ScoreBase 7.1
Base 7.1 AV:N/AC:M/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
Product Names From Source
Cisco Web Security Appliance (WSA), Cisco Secure Web Appliance

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