Hackers are targeting a vulnerability in Cisco’s Adaptive Security Appliance (ASA) after security researchers published a proof-of-concept (PoC) for a successful exploit.

Positive Technologies SWARM, the security company’s offensive research team, published an exploit PoC for the flaw tracked as CVE-2020-3580 last week. This was originally patched in October 2020 alongside CVE-2020-3581 through to CVE-2020-3583.

This issue, which is considered to be moderately severe, concerns multiple vulnerabilities in the web services interface of Cisco ASA software and Cisco Firepower Threat Defense (FTD) software. 

On unpatched systems, Cisco ASA/FTD software web services don’t sufficiently validate user-supplied inputs. To exploit the bug successfully, hackers would need to convince a user on the interface to click on a malicious link. The vulnerability is rated 6.1 out of ten on the CVSS threat severity scale.

Exploitation could allow an attacker to remotely conduct cross-site scripting (XSS) attacks on affected devices that haven’t been patched. Cisco ASA Software is the core operating system that powers the Cisco ASA family, comprising devices that offer firewall tools among other security-oriented services.

Since the PoC was posted online, Positive Technologies researcher Mikhail Klyuchnikov reported that many other researchers are also chasing bug bounties for this vulnerability. Tenable researchers have also reported that attacks are exploiting CVE-2020-3580.

Cisco issued a patch for this flaw in October 2020, but the fix for CVE-2020-3581 was only partial, and the company had to issue a second patch in April this year. As of last July, there were 85,000 ASA/FTD devices distributed across the business landscape. 

Cisco Adaptive Security Appliance (ASA) Software is the core operating system that powers the Cisco ASA family. It offers firewall tools for various ASA devices, with ASA Software also integrating with other critical security technologies to deliver security-oriented products. 

Businesses are being advised to patch their systems with the latest update to avoid falling victim to successful attacks.