Actively exploited vulnerability

Cisco IOS software: denial of service flaw under attack

CVE-2017-12234 · Cisco IOS Software Common Industrial Protocol Request Denial-of-Service Vulnerability

Concerns everyone who uses it7.5 high

What is affected

Cisco IOS software is found on ordinary personal computers and phones, so this is not only a problem for companies. If you use it and have not updated since the fix was released, you are exposed.

There is a vulnerability in the implementation of the Common Industrial Protocol (CIP) feature in Cisco IOS could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service.

CISA's description

What an attacker can do

This is a denial of service flaw. It lets an attacker crash the product or make it unavailable to the people who rely on it.

How it is reached
Over the internet or network
Access the attacker needs
No account needed
Does the victim have to do something?
No, works without the victim doing anything

What to do

  1. Update Cisco IOS software now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
  2. Turn on automatic updates so the next fix arrives without you having to look for it.
  3. If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.

Apply updates per vendor instructions.

Action required by CISA for US federal agencies

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on March 3, 2022, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by March 24, 2022, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 7.1% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 94% of all scored vulnerabilities.

Its CVSS severity score is 7.5 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

Multiple vulnerabilities in the implementation of the Common Industrial Protocol (CIP) feature in Cisco IOS 12.4 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerabilities are due to the improper parsing of crafted CIP packets destined to an affected device. An attacker could exploit these vulnerabilities by sending crafted CIP packets to be processed by an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvc43709.

NIST National Vulnerability Database
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