Cisco informed customers on Wednesday that it has become aware of malicious attacks attempting to exploit a recently patched vulnerability affecting the company’s Adaptive Security Appliance (ASA) software.

No other information has been provided by the networking giant, but it’s worth noting that a proof-of-concept (PoC) exploit designed to cause a denial-of-service (DoS) condition on devices running ASA software was made public this week.

Cato Networks reported finding roughly 120,000 potentially vulnerable Cisco devices connected to the Internet, with a vast majority located in the United States and Europe.

The ASA software vulnerability, tracked as CVE-2018-0101, allows a remote and unauthenticated attacker to execute arbitrary code or cause a DoS condition.

The flaw affects several products running ASA software, including Firepower firewalls, 3000 series industrial security appliances, ASA 5000 and 5500 series appliances, 1000V cloud firewalls, ASA service modules for routers and switches, and Firepower Threat Defense (FTD) software. Cisco first notified customers about the availability of fixes on January 29.

Cisco initially said the security hole was related to the webvpn feature, but it later discovered that more than a dozen other features were impacted as well. The company released new patches this week after identifying new attack vectors and determining that the original fix had been incomplete.

The details of the vulnerability were disclosed on February 2 by Cedric Halbronn, the NCC Group researcher who reported the issue to Cisco.

“When exploited, this vulnerability known as CVE-2018-0101 allows the attacker to see all of the data passing through the system and provides them with administrative privileges, enabling them to remotely gain access to the network behind it,” NCC Group said. “Targeting the vulnerability without a specially-crafted exploit would cause the firewall to crash and would potentially disrupt the connectivity to the network.”

SecurityWeek has reached out to Cisco to see if the company can provide additional details regarding the malicious attacks and will update this article if the company responds.

Cisco on Wednesday also released new advisories describing several critical and high severity vulnerabilities, including a remote code execution flaw in RV132W ADSL2+ and RV134W VDSL2 routers, a DoS flaw in Cisco Virtualized Packet Core-Distributed Instance (VPC-DI) software, a command execution flaw in UCS Central, and an authentication bypass bug in Cisco Policy Suite.

UPDATE 02/09/2018 Cisco has provided the following statement to SecurityWeek:

“Cisco is aware of the Proof of Concept code, which can result in either a DoS or RCE. The PoC is publicly available on the internet and it’s been reported to the Cisco PSIRT team that attempted exploitation using the PoC has occurred.”

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