#VU6698 Denial of service in Allen-Bradley MicroLogix 1400 and Allen-Bradley MicroLogix 1100 - CVE-2017-7902

Vulnerability identifier: #VU6698

Vulnerability risk: Low

CVSSv4.0: 1.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2017-7902

CWE-ID: CWE-323

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Allen-Bradley MicroLogix 1400
Hardware solutions / Office equipment, IP-phones, print servers
Allen-Bradley MicroLogix 1100
Hardware solutions / Office equipment, IP-phones, print servers

Vendor: Rockwell Automation

Description
The vulnerability allows a remote attacker to cause DoS condition on the target system.

The vulnerability exists due to reuse of nonces by the affected software. A remote attacker can capture and replay a valid request until the nonce is changed.

Successful exploitation of the vulnerability may result in denial of service.

Mitigation
Update to version 21.00

Vulnerable software versions

Allen-Bradley MicroLogix 1400: 1766-L32AWAA 16.00 - 1766-L32AWA 16.00

Allen-Bradley MicroLogix 1100: 1763-L16DWD 16.00 - 1763-L16AWA 16.00

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External links
https://ics-cert.us-cert.gov/advisories/ICSA-17-115-04

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.