Earth Lusca's New SprySOCKS Linux Backdoor Targets Government Entities

CVE-2019-18935 is a .NET deserialization flaw (CWE-502) in the RadAsyncUpload function of Progress Telerik UI for ASP.NET AJAX through version 2019.3.1023. It is triggered when an attacker who knows the Telerik upload encryption keys — most commonly because the earlier flaws CVE-2017-11317 or CVE-2017-11357 exposed them, though keys can be obtained by other means — sends crafted serialized data to RadAsyncUpload, allowing remote code execution without authentication. Successful exploitation gives an attacker arbitrary code execution on the hosting IIS/ASP.NET web server, reflected in the critical 9.8 CVSS score. Any web application built with Telerik UI for ASP.NET AJAX at or below 2019.3.1023 is affected, unless 2019.3.1023 has the non-default hardening setting enabled (as of 2020.1.114 a default setting prevents the exploit). Exploitation is rampant in the wild: the flaw was added to CISA KEV on 2021-11-03 with known ransomware use, carries a 99.7% EPSS probability of exploitation, has multiple public exploits (Bishop Fox, RAU_crypto, noperator), and has been used by multiple threat groups — including ransomware and government-linked actors — to breach organizations including a U.S. federal agency.

Do: Upgrade to Progress Telerik UI for ASP.NET AJAX 2020.1.114 or later, where a default setting prevents exploitation (or, if staying on 2019.3.1023, enable the non-default hardening setting); per CISA KEV, apply updates per vendor instructions. Because exploitation requires the encryption keys to be known, also patch the older CVE-2017-11317/CVE-2017-11357 key-disclosure flaws or rotate the Telerik upload encryption keys. Check internet-facing IIS/ASP.NET applications for exposed RadAsyncUpload handlers and indicators of compromise, given known ransomware and federal-agency breaches.

CVE-2019-9621 is a server-side request forgery (SSRF, CWE-918) in the ProxyServlet component of Synacor Zimbra Collaboration Suite, triggerable by an unauthenticated attacker sending crafted HTTP requests to the servlet. By making the Zimbra server issue requests of the attacker's choosing, the attacker can probe or access internal network resources from the server's position, with high confidentiality impact (CVSS 3.1: 7.5, AV:N/PR:N/C:H). Public proof-of-concept code is available, including references that pair the SSRF with an XXE flaw (e.g., a Metasploit module for Zimbra XXE-to-RCE), and Exploit-DB/PacketStorm listings cover both the SSRF and the combined injection chain. Any organization running Zimbra 8.6 before patch 13, 8.7.x before 8.7.11 patch 10, or 8.8.x before 8.8.10 patch 7 / 8.8.11 patch 3 is affected. Exploitation is confirmed in the wild: CISA added the flaw to the KEV catalog on 2025-07-07 due to active exploitation, and related reporting ties Zimbra exploitation to the Earth Lusca threat actor, whose SprySOCKS Linux backdoor has targeted government entities.

Do: Apply Synacor/Zimbra's vendor patches: 8.6.0 patch 13, 8.7.11 patch 10, 8.8.10 patch 7, or 8.8.11 patch 3 (or later) — noting 8.6/8.7 are legacy releases, so plan migration to a supported version; federal agencies must also comply with BOD 22-01. Because EPSS is very high (81%) and active exploitation is confirmed, prioritize internet-facing Zimbra servers first. Hunt for compromise by reviewing logs for unauthenticated requests to the ProxyServlet/autodiscover endpoints, unexpected outbound connections from the Zimbra host, and signs of Linux backdoors such as SprySOCKS on the mail server.

Synacor Zimbra Collaboration Suite (ZCS) contains an improper restriction of XML external entity (XXE) vulnerability (CWE-611) in its mailboxd component, meaning XML parsing accepts external entity references that the parser should restrict. By submitting crafted XML that ZCS parses in mailboxd, an attacker can typically direct the server to fetch external entities, potentially disclosing local files or issuing server-side requests; the available data does not specify authentication requirements or exact affected version ranges. Organizations running Synacor Zimbra Collaboration Suite are affected. The flaw is confirmed as exploited in the wild: CISA added CVE-2019-9670 to the Known Exploited Vulnerabilities catalog on 2022-01-10, and EPSS assigns a 100% probability of exploitation within 30 days; no public PoC is listed and ransomware association is listed as unknown.

Do: Apply updates per Synacor/Zimbra instructions, as required by the CISA KEV catalog; because no fixed version numbers are provided in the available data, administrators of all ZCS deployments should consult current vendor advisories and patch promptly. As interim mitigation, restrict or disable external entity resolution in XML processing and limit exposure of mailboxd-facing services. Check mailboxd logs and outbound network activity for signs of entity resolution or unexpected connections, and prioritize this fix given the 2022-01-10 KEV listing and 100% EPSS score.

GitLab CE/EE versions from 11.9 onward fail to properly validate image files before passing them to the bundled ExifTool file parser, enabling command/code injection (CWE-94). A remote, unauthenticated attacker triggers it by getting the server to parse a specially crafted image (e.g., through file-upload features), with no credentials or user interaction required. Successful exploitation yields arbitrary command execution on the GitLab server, exposing source code, credentials, CI/CD data, and the wider network (CVSS 10.0, scope-changed). All self-managed GitLab Community and Enterprise Edition deployments on affected versions are exposed. The flaw is actively exploited in the wild: it is on CISA's KEV with known ransomware use, public PoCs exist, and 2021 campaigns used it for ransomware, cryptojacking, and access brokering against GitLab servers.

Do: Upgrade immediately to the patched releases - 13.10.3 or later, or the corresponding 13.9.6/13.8.6/13.7.9 backports - per vendor instructions, as required for KEV entries. Until patched, restrict network access to internet-facing GitLab instances and verify the bundled ExifTool is current. Hunt for signs of compromise (suspicious processes or cron jobs, cryptominers, webshells, new SSH keys, unexpected outbound connections), given documented ransomware and cryptojacking abuse.

A external control of file name or path in Fortinet FortiNAC versions 9.4.0, 9.2.0 through 9.2.5, 9.1.0 through 9.1.7, 8.8.0 through 8.8.11, 8.7.0 through 8.7.6, 8.6.0 through 8.6.5, 8.5.0 through 8.5.4, 8.3.7 may allow an unauthenticated attacker to execute unauthorized code or commands via specifically crafted HTTP request.

Fortinet's FortiOS, FortiProxy, and FortiSwitchManager contain an authentication bypass vulnerability (CWE-288) that lets an unauthenticated remote attacker gain access to the administrative interface. It is triggered by sending specially crafted HTTP or HTTPS requests directly to the admin interface, with no credentials or exploit code required. By bypassing authentication, an attacker can perform administrative operations on the device, such as modifying configuration or creating privileged accounts. Any organization running the affected products is exposed, particularly where the management interface is reachable from the internet. The flaw is being actively exploited: it was added to CISA's Known Exploited Vulnerabilities catalog on 2022-10-11 with known ransomware use, and EPSS assigns it roughly a 100% probability of exploitation within 30 days, although no public PoC is known.

Do: Upgrade FortiOS, FortiProxy, and FortiSwitchManager to the fixed releases identified in Fortinet's advisory per the KEV required action. As mitigation, restrict access to the admin interface (e.g., disable WAN-facing management and use local-in policies or allow-lists for management IPs). Review admin logs and device configuration for signs of unauthorized access, such as unexpected admin accounts, added SSH keys, or config changes.