Multiple APT Groups Exploit Critical Pulse Secure Zero

Ivanti Pulse Connect Secure, an enterprise SSL VPN appliance, contains an arbitrary file read vulnerability (CWE-22, path traversal) that requires no authentication. An unauthenticated remote attacker with network access to the appliance over HTTPS can send a specially crafted URI containing traversal sequences to read arbitrary files from the device. The attacker gains access to sensitive appliance files, potentially including configuration or credential material useful for further compromise, and CISA records known ransomware use of this flaw. Any organization running Pulse Connect Secure, especially gateways exposed to the internet for remote access, is affected. Exploitation is established: CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2021-11-03 with known ransomware use, EPSS assigns a 100% probability of exploitation in the next 30 days, and no public PoC is known.

Do: Apply updates per Ivanti's instructions, the required action in the CISA KEV entry, prioritizing internet-facing Pulse Connect Secure gateways, and consult the vendor advisory for the applicable fixed release since no version range is provided here. Where patching is not immediate, restrict HTTPS access to the appliance and hunt for signs of exploitation (unexpected file reads, anomalous VPN logins or sessions, and follow-on ransomware activity), as CISA reports known ransomware use.

CVE-2020-8243 is a code injection flaw (CWE-94) in the administrator web interface of Ivanti Pulse Connect Secure versions prior to 9.1R8.2. An authenticated attacker with administrative privileges can upload a custom template through the admin interface, which results in arbitrary code execution on the appliance. Successful exploitation gives the attacker full control over the VPN gateway, including access to network traffic, stored credentials, and a foothold for pivoting into the internal network. Any organization running an affected Pulse Connect Secure version is exposed, and administrators should note the flaw requires admin-level access, which lowers risk when the management interface is not reachable by untrusted users. The vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03) and carries a very high EPSS score of about 91%, indicating active or highly likely exploitation; Pulse Secure VPN appliances broadly were also the target of APT exploitation activity in 2021.

Do: Upgrade Pulse Connect Secure to 9.1R8.2 or later per the vendor's instructions, as required by the CISA KEV listing. Restrict the admin web interface to trusted management networks and review appliances for suspicious custom templates, modified configurations, or added administrator accounts, since Pulse Secure devices have been a documented target of APT intrusion tooling.

Ivanti Pulse Connect Secure versions before 9.1R9 contain a vulnerability (mapped to CWE-434) in the administrative web interface in which compressed uploads are handled with uncontrolled gzip extraction. An authenticated attacker with high-privilege (admin-level) access to that interface can send a crafted gzip-compressed file, triggering arbitrary code execution on the appliance with high impact to confidentiality, integrity, and availability (CVSS 3.1: 7.2, AV:N/PR:H). Successful exploitation yields arbitrary code execution on the VPN appliance itself, effectively enabling full compromise of the gateway that terminates the organization's VPN sessions. Any organization running Pulse Connect Secure on a release prior to 9.1R9 is affected, making the typical target an enterprise or government SSL VPN appliance accessible to anyone holding admin credentials. Exploitation is in the wild: the flaw is in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03), carries a 96.5% EPSS exploitation probability (100th percentile), and a public proof of concept is available.

Do: Upgrade Pulse Connect Secure to 9.1R9 or later per the vendor's instructions; given the related patch-bypass flaw CVE-2021-22937 and the 'new urgent update' headlines, ensure the most recent available 9.1R release is applied rather than relying solely on the original 9.1R9 fix. Restrict the admin web interface to trusted management networks and review administrative accounts. Because the flaw is on CISA's KEV list and CISA has published malware analysis reports for Pulse Secure-targeted samples, hunt patched and unpatched devices for signs of compromise (e.g., web shells or implants).

Ivanti Pulse Connect Secure, a widely deployed SSL VPN appliance, contains a use-after-free vulnerability in its license services. A remote, unauthenticated attacker can trigger the flaw via the license services and gain arbitrary code execution on the appliance, which is a high-value target because it terminates VPN sessions for enterprise networks. Any organization running an affected Pulse Connect Secure release is potentially affected; the source data does not specify exact version ranges, so administrators should compare their release against Ivanti's advisory. Exploitation is confirmed in the wild: the flaw is on CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03) with known ransomware use, and its 47.2% EPSS score (99th percentile) indicates a high likelihood of exploitation within 30 days.

Do: Apply the updates per Ivanti's instructions immediately, as CISA's required action specifies. Because exploited appliances have often retained persistent webshells/backdoors even after patching, also hunt for indicators of compromise (modified appliance files, unexpected processes or accounts) and follow Ivanti's remediation guidance rather than only installing the update. Until patched, restrict or closely monitor internet access to the appliance.