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Vulnerability of ICMP: denial of service via ICMP Type 3 Code 3, BlackNurse

Synthesis of the vulnerability 

An attacker can send numerous ICMP Type 3 Code 3 packets to some routers/firewalls, in order to trigger a denial of service.
Vulnerable products: ASA, IOS by Cisco, Cisco Router, FortiGate, FortiGate Virtual Appliance, FortiOS, Palo Alto Firewall PA***, PAN-OS.
Severity of this weakness: 2/4.
Creation date: 16/11/2016.
Références of this bulletin: Black Nurse, sk114500, VIGILANCE-VUL-21138.

Description of the vulnerability 

The ICMP protocol uses packets of Type 3 Code 3 to announce that a port is unreachable. This packet is usually sent as a reply to the sender of a packet sent to a closed TCP/UDP port.

However, when numerous ICMP Type 3 Code 3 packets are received, some devices uselessly consume many resources to process them.

An attacker can therefore send numerous ICMP Type 3 Code 3 packets to some routers/firewalls, in order to trigger a denial of service.
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This security alert impacts software or systems such as ASA, IOS by Cisco, Cisco Router, FortiGate, FortiGate Virtual Appliance, FortiOS, Palo Alto Firewall PA***, PAN-OS.

Our Vigil@nce team determined that the severity of this security weakness is medium.

The trust level is of type confirmed by the editor, with an origin of internet client.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this security announce.

Solutions for this threat 

Cisco: solution for BlackNurse.
A workaround is to:
 - Block ICMP Type 3 Code 3 packets at the top router.
 - Use a Rate Limit on ICMP Type 3 Code 3.
 - Use a non-vulnerable firewall (iptables, OpenBSD, pfSense, Check Point, Juniper).

Fortinet: solution for BlackNurse.
The solution is indicated in information sources.

Palo Alto: solution for BlackNurse.
The solution is indicated in information sources.
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