Cisco Jabber Extensible Communications Platform and Cisco Unified Presence contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service vulnerability. Updates are available.
Cisco Jabber Extensible Communications Platform (Jabber XCP) and Cisco Unified Presence contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected system.
An unauthenticated, remote attacker can exploit the vulnerability by sending malicious XML content to an affected system. If successful, the attacker could trigger the exhaustion of resources, leading to a temporary DoS condition. Repeated attacks could result in a sustained DoS condition, disrupting normal operations for users.
Functional exploit code is publicly available.
Cisco has confirmed this vulnerability in a security advisory and has issued updated software.
The following products are vulnerable:
Cisco Unified Presence software versions prior to 8.5(4)
Jabber XCP software versions prior to 220.127.116.11581 and prior to 18.104.22.168561
It is likely that an attacker would need to have access to an internal, private network to successfully exploit this vulnerability. This requirement could limit the possibility of a successful attack.
Successful exploitation could allow an unauthenticated, remote attacker to cause a DoS condition on an affected server by exhausting available system resources. Repeated exploits could result in a sustained DoS condition, disrupting normal operations for users for longer durations.
The vulnerability is due to the parsing of XML data in both Jabber XCP, including JabberNow appliances, and Cisco Unified Presence. These products are vulnerable to the Exponential Entity Expansion attack. This attack is better known as an XML Bomb, referring to an XML document that is considered to be valid by the rules of the XML schema, but causes the parser or underlying server to crash or hang. This attack is also more commonly referred to the Billion Laughs Attack, due to the use of XML parsers to expand the string lol or ha up to a billion times or until server resources were exhausted.
This attack combines certain properties of XML to create valid but malicious XML using an extreme level of nested substitutions. When the XML parser attempts to expand all the nested entities, it will exhaust all the server resources.
An unauthenticated, remote attacker could trigger high CPU and memory usage from the XML parsers in Jabber XCP, including JabberNow appliances, and Cisco Unified Presence. This will result in the exhaustion of resources, causing processes to crash. This attack affects both client-to-server connections as well as server-to-server (federation) links.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
Administrators are advised to monitor affected systems.
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at firstname.lastname@example.org.
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