Week in review: Two Cisco ASA zero-days exploited, MITRE breach, GISEC Global 2024

CVE-2022-38028 is an elevation-of-privilege vulnerability (CVSS 3.1: 7.8) in the Microsoft Windows Print Spooler, the service that manages print jobs on Windows machines. An attacker who can already run low-privileged code on a vulnerable system can exploit the flaw locally, with no user interaction required, to escalate to SYSTEM privileges and take full control of the host (high confidentiality, integrity, and availability impact). It affects a broad set of Windows releases — Windows 10 builds 1507 through 21H2, Windows 11 22H2, Windows 8.1 and Windows RT 8.1, and Windows Server 2012, 2016, and 2019 — so most unpatched Windows estates are in scope. Exploitation is confirmed in the wild: CISA added the bug to the KEV catalog on 2024-04-23 (ransomware use unknown), and public reporting attributes active use to the Russia-linked APT28 group, whose custom 'GooseEgg' tool leverages this NSA-reported flaw to run payloads with elevated privileges; Microsoft shipped the fix in its April 2024 Patch Tuesday. EPSS is 14.9% (96th percentile), indicating elevated near-term exploitation risk on top of the already-observed APT28 activity.

Do: Apply Microsoft's security updates for the affected Windows releases (fixed in the April 2024 Patch Tuesday); as a KEV entry, CISA requires applying vendor mitigations or discontinuing use of unpatched versions. On servers where printing is not required, disabling the Print Spooler service removes the local attack path. Given confirmed APT28 use of the 'GooseEgg' exploit, hunt for related activity on unpatched hosts and prioritize patching endpoints belonging to organizations and users targeted by APT28.

Ivanti Connect Secure (formerly Pulse Connect Secure) and Ivanti Policy Secure appliances contain a command injection flaw (CWE-77) in their web components, triggered when an authenticated administrator sends crafted requests to the appliance. The bug can be chained with the separate authentication bypass CVE-2023-46805, allowing an unauthenticated attacker to achieve the same result. Successful exploitation lets an attacker execute arbitrary commands and code on the appliance, providing a foothold into the networks behind the VPN or network access control gateway. Any organization running these appliances, typically enterprises and government agencies often deployed directly on the internet perimeter, is affected. Exploitation is confirmed in the wild: the flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2024-01-10 with known ransomware use and EPSS assigns a 100% probability of exploitation within 30 days, although no public proof-of-concept is available.

Do: Apply Ivanti's mitigations or patched builds immediately per vendor instructions, addressing the chained authentication bypass CVE-2023-46805 at the same time, and discontinue or restrict use of any appliance for which mitigations are unavailable, especially if it is internet-facing. Because exploitation with ransomware use is known, assume compromise is possible: review appliance web logs for suspicious requests and run Ivanti's integrity-checking guidance to verify appliance images before and after remediation. Where feasible, restrict direct internet exposure of the appliance web interface and monitor for further vendor advisories.

CVE-2024-20353 is a denial-of-service flaw in the management and VPN web servers of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software, caused by incomplete error checking when parsing an HTTP header (tracked as CWE-835, a loop-exit defect). An unauthenticated, remote attacker can trigger it by sending a crafted HTTP request to the device's web server, causing the firewall/VPN appliance to reload unexpectedly. A successful exploit yields no data theft from the flaw itself but takes the device offline, and repeated requests can sustain an outage of the edge firewall and VPN service. Any organization running ASA or FTD with these web servers reachable by attackers is exposed, which includes nearly every internet-facing Cisco edge deployment. The flaw is being actively exploited: it was added to CISA's Known Exploited Vulnerabilities catalog on 2024-04-24, is referenced in a public Cisco Talos writeup on the ArcaneDoor campaign, where suspected state-sponsored (China-linked) actors chained it with CVE-2024-20359 to backdoor ASA perimeter devices, and EPSS assigns it a 70.7% probability of exploitation within 30 days (99th percentile).

Do: Upgrade ASA and FTD to the fixed releases listed in Cisco's security advisory (version ranges not included in this data), and because attackers in the ArcaneDoor campaign may have persisted on devices via the related CVE-2024-20359 backdoor, check for unexpected configuration changes or persistence before and after patching. Restrict exposure of the ASA/FTD management and VPN web servers to trusted source addresses while remediation is pending. Per CISA's KEV required action, apply vendor mitigations or discontinue use of the product if mitigations are unavailable.

In Flowmon versions prior to 11.1.14 and 12.3.5, an operating system command injection vulnerability has been identified. An unauthenticated user can gain entry to the system via the Flowmon management interface, allowing for the execution of arbitrary system commands.

CrushFTP contains a server-side template injection flaw (CWE-94, CWE-1336) that allows unauthenticated remote attackers to escape the Virtual File System (VFS) sandbox. The flaw is triggered by unauthenticated network requests to any CrushFTP server running versions before 10.7.1 or 11.1.0 on any platform. Successful exploitation lets an attacker read files from the filesystem outside the VFS sandbox, bypass authentication to gain administrative access, and execute arbitrary code on the server. All CrushFTP deployments on prior versions are affected, especially internet-exposed file transfer servers. The vulnerability is being actively exploited in the wild: it was added to CISA's Known Exploited Vulnerabilities catalog on 2024-04-24, EPSS puts 30-day exploitation probability at 99.5%, and public scans have identified at least 1,400 vulnerable exposed servers.

Do: Upgrade immediately to CrushFTP 10.7.1 (10.x line) or 11.1.0 (11.x line) or later, as the vendor has urged, or apply the vendor's documented mitigations if patching is delayed. Prioritize internet-facing instances, and check them for signs of compromise such as unauthorized administrative access or unexpected file reads. Public proof-of-concept code exists, so assume unpatched exposed servers will be exploited.