Suspected China-Nexus Threat Actor Actively Exploiting Critical Ivanti Connect Secure Vulnerability (CVE-2025-22457) | Google Cloud Blog

Written by: John Wolfram, Michael Edie, Jacob Thompson, Matt Lin, Josh Murchie

On Thursday, April 3, 2025, Ivanti disclosed a critical security vulnerability, CVE-2025-22457, impacting Ivanti Connect Secure (“ICS”) VPN appliances version 22.7R2.5 and earlier. CVE-2025-22457 is a buffer overflow vulnerability, and successful exploitation would result in remote code execution. Mandiant and Ivanti have identified evidence of active exploitation in the wild against ICS 9.X (end of life) and 22.7R2.5 and earlier versions. Ivanti and Mandiant encourage all customers to upgrade as soon as possible. 

The earliest evidence of observed CVE-2025-22457 exploitation occurred in mid-March 2025. Following successful exploitation, we observed the deployment of two newly identified malware families, the TRAILBLAZE in-memory only dropper and the BRUSHFIRE passive backdoor. Additionally, deployment of the previously reported SPAWN ecosystem of malware attributed to UNC5221 was also observed. UNC5221 is a suspected China-nexus espionage actor that we previously observed conducting zero-day exploitation of edge devices dating back to 2023.

A patch for CVE-2025-22457 was released in ICS 22.7R2.6 on February 11, 2025. The vulnerability is a buffer overflow with a limited character space, and therefore it was initially believed to be a low-risk denial-of-service vulnerability. We assess it is likely the threat actor studied the patch for the vulnerability in ICS 22.7R2.6 and uncovered through a complicated process, it was possible to exploit 22.7R2.5 and earlier to achieve remote code execution.

Ivanti released patches for the exploited vulnerability and Ivanti customers are urged to follow the actions in the Security Advisory to secure their systems as soon as possible.

Post-Exploitation Tactics, Techniques, and Procedures

Following successful exploitation, Mandiant observed the deployment of two newly identified malware families tracked as TRAILBLAZE and BRUSHFIRE through a shell script dropper. Mandiant has also observed the deployment of the SPAWN ecosystem of malware. Additionally, similar to previously observed behavior, the actor attempted to modify the Integrity Checker Tool (ICT) in an attempt to evade detection.  

Shell-script Dropper

Following successful exploitation of CVE-2025-22457, Mandiant observed a shell script being leveraged that executes the TRAILBLAZE dropper. This dropper injects the BRUSHFIRE passive backdoor into a running /home/bin/web process. The first stage begins by searching for a /home/bin/web process that is a child process of another /home/bin/web process (the point of this appears to be to inject into the web process that is actually listening for connections). It then creates the the following files and associated content:

• /tmp/.p: contains the PID of the /home/bin/web process.

• /tmp/.m: contains a memory map of that process (human-readable).

• /tmp/.w: contains the base address of the web binary from that process

• /tmp/.s: contains the base address of libssl.so from that process

• /tmp/.r: contains the BRUSHFIRE passive backdoor

• /tmp/.i: contains the TRAILBLAZE dropper

The shell script then executes /tmp/.i, which is the second stage in-memory only dropper tracked as TRAILBLAZE. It then deletes all of the temporary files previously created (except for /tmp/.p), as well as the contents of the /data/var/cores directory. Next, all child processes of the /home/bin/web process are killed and the /tmp/.p file is deleted. All of this behavior is non-persistent, and the dropper will need to be re-executed if the system or process is rebooted.

TRAILBLAZE

TRAILBLAZE is an in-memory only dropper written in bare C that uses raw syscalls and is designed to be as minimal as possible, likely to ensure it can fit within the shell script as Base64. TRAILBLAZE injects a hook into the identified /home/bin/web process. It will then inject the BRUSHFIRE passive backdoor into a code cave inside that process.

BRUSHFIRE

BRUSHFIRE is a passive backdoor written in bare C that acts as an SSL_read hook. It first executes the original SSL_read function, and checks to see if the returned data begins with a specific string. If the data begins with the string, it will XOR decrypt then execute shellcode contained in the data. If the received shellcode returns a value, the backdoor will call SSL_write to send the value back.

SPAWNSLOTH

As detailed in our previous blog post, SPAWNSLOTH acts as a log tampering component tied to the SPAWNSNAIL backdoor. It targets the dslogserver process to disable both local logging and remote syslog forwarding.

SPAWNSNARE

SPAWNSNARE is a utility that is written in C and targets Linux. It can be used to extract the uncompressed linux kernel image (vmlinux) into a file and encrypt it using AES without the need for any command line tools.

SPAWNWAVE

SPAWNWAVE is an evolved version of SPAWNANT that combines capabilities from other members of the SPAWN* malware ecosystem. SPAWNWAVE overlaps with the publicly reported SPAWNCHIMERA and RESURGE malware families.

Attribution

Google Threat Intelligence Group (GTIG) attributes the exploitation of CVE-2025-22457 and the subsequent deployment of the SPAWN ecosystem of malware to the suspected China-nexus espionage actor UNC5221. GTIG has previously reported UNC5221 conducting zero-day exploitation of CVE-2025-0282, as well as the exploitation CVE-2023-46805 and CVE-2024-21887. 

Furthermore, GTIG has also previously observed UNC5221 conducting zero-day exploitation of CVE-2023-4966, impacting NetScaler ADC and NetScaler Gateway appliances. UNC5221 has targeted a wide range of countries and verticals during their operations, and has leveraged an extensive set of tooling, spanning passive backdoors to trojanized legitimate components on various edge appliances. 

GTIG assesses that UNC5221 will continue pursuing zero-day exploitation of edge devices based on their consistent history of success and aggressive operational tempo. Additionally, as noted in our prior blog post detailing CVE-2025-0282 exploitation, GTIG has observed UNC5221 leveraging an obfuscation network of compromised Cyberoam appliances, QNAP devices, and ASUS routers to mask their true source during intrusion operations.

Conclusion

This latest activity from UNC5221 underscores the ongoing sophisticated threats targeting edge devices globally. This campaign, exploiting the n-day vulnerability CVE-2025-22457, also highlights the persistent focus of actors like UNC5221 on edge devices, leveraging deep device knowledge and adding to their history of using both zero-day and now n-day flaws. This activity aligns with the broader strategy GTIG has observed among suspected China-nexus espionage groups who invest significantly in exploits and custom malware for critical edge infrastructure.

Recommendations

Mandiant recommends organizations immediately apply the available patch by upgrading Ivanti Connect Secure (ICS) appliances to version 22.7R2.6 or later to address CVE-2025-22457. Additionally organizations should use the external and internal Integrity Checker Tool (“ICT”) and contact Ivanti Support if suspicious activity is identified. To supplement this, defenders should actively monitor for core dumps related to the web process, investigate ICT statedump files, and conduct anomaly detection of client TLS certificates presented to the appliance.

Acknowledgements

We would like to thank Daniel Spicer and the rest of the team at Ivanti for their continued partnership and support in this investigation. Additionally, this analysis would not have been possible without the assistance from analysts across Google Threat Intelligence Group and Mandiant’s FLARE, we would like to specifically thank Christopher Gardner and Dhanesh Kizhakkinan of FLARE for their support.

Indicators of Compromise

To assist the security community in hunting and identifying activity outlined in this blog post, we have included indicators of compromise (IOCs) in a GTI Collection for registered users.

YARA Rules

rule M_APT_Installer_SPAWNANT_1
{ 
    meta: 
        author = "Mandiant" 
        description = "Detects SPAWNANT. SPAWNANT is an 
Installer targeting Ivanti devices. Its purpose is to persistently 
install other malware from the SPAWN family (SPAWNSNAIL, 
SPAWNMOLE) as well as drop additional webshells on the box." 

    strings: 
        $s1 = "dspkginstall" ascii fullword
        $s2 = "vsnprintf" ascii fullword
        $s3 = "bom_files" ascii fullword
        $s4 = "do-install" ascii
        $s5 = "ld.so.preload" ascii
        $s6 = "LD_PRELOAD" ascii
        $s7 = "scanner.py" ascii

    condition: 
        uint32(0) == 0x464c457f and 5 of ($s*)
}

rule M_Utility_SPAWNSNARE_1 {
    meta:
         author = "Mandiant"
        description = "SPAWNSNARE is a utility written in C that targets 
Linux systems by extracting the uncompressed Linux kernel image 
into a file and encrypting it with AES."

    strings:
        $s1 = "\x00extract_vmlinux\x00"
        $s2 = "\x00encrypt_file\x00"
        $s3 = "\x00decrypt_file\x00"
        $s4 = "\x00lbb_main\x00"
        $s5 = "\x00busybox\x00"
        $s6 = "\x00/etc/busybox.conf\x00"

    condition:
        uint32(0) == 0x464c457f
        and all of them

}

rule M_APT_Utility_SPAWNSLOTH_2
{ 
    meta: 
        author = "Mandiant" 
        description = "Hunting rule to identify strings found in SPAWNSLOTH"

    strings: 
        $dslog = "dslogserver" ascii fullword
        $hook1 = "g_do_syslog_servers_exist" ascii fullword
        $hook2 = "ZN5DSLog4File3addEPKci" ascii fullword
        $hook3 = "funchook" ascii fullword

    condition: 
        uint32(0) == 0x464c457f and all of them
}

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• Threat Intelligence

• Is The Sofistication In The Room With Us? - X-Forwarded-For and Ivanti Connect Secure

Apple has released emergency security updates to patch a zero-day bug the company describes as exploited in "extremely sophisticated" attacks.

The vulnerability is tracked as CVE-2025-24201 and was found in the WebKit cross-platform web browser engine used by Apple's Safari web browser and many other apps and web browsers on macOS, iOS, Linux, and Windows.

CVE ID CVE-2024-56325 CVSS SCORE 9.8, AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H AFFECTED VENDORS Apache AFFECTED PRODUCTS Pinot VULNERABILITY DETAILS
This vulnerability allows remote attackers to bypass authentication on affected installations of Apache Pinot. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the AuthenticationFilter class. The issue results from insufficient neutralization of special characters in a URI. An attacker can leverage this vulnerability to bypass authentication on the system.

ADDITIONAL DETAILS
Fixed in version 1.3.0

French cybersecurity company Sekoia observed the unknown threat actors deploying a backdoor by leveraging CVE-2023-20118 (CVSS score: 6.5), a critical security flaw impacting Cisco Small Business RV016, RV042, RV042G, RV082, RV320, and RV325 Routers that could result in arbitrary command execution on susceptible devices.

CVE-2023-20118 is leading to a webshell installation.

Executive Summary

This report updates the findings on CVE-2025-24085, a use-after-free vulnerability affecting Apple's IDS subsystem and iMessage's BlastDoor sandboxing. Findings (As of February 20, 2025)

iOS 18.3.1 remains vulnerable despite Apple's February 19, 2025, mitigation deadline.
BlastDoor is bypassed, enabling unsandboxed iMessage processing.
Privilege escalation attempts detected, suggesting a possible kernel exploit.
Unauthorized decryption and authentication tampering observed, raising concerns about iMessage interception and data exposure.

The exploit remains active in the wild, requiring immediate action.

https://github.com/orgs/community/discussions/152523

This issue affects Session Smart Router, Session Smart Conductor, WAN Assurance Managed Router. Severity Critical Severity Assessment (CVSS) Score

CVSS: v3.1: 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) SEVERITY:CRITICAL CVSS: v4.0: 9.3 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) SEVERITY:CRITICAL Problem

An Authentication Bypass Using an Alternate Path or Channel vulnerability in Juniper Networks Session Smart Router may allow a network-based attacker to bypass authentication and take administrative control of the device.

This issue affects Session Smart Router:

from 5.6.7 before 5.6.17, 
from 6.0.8,
from 6.1 before 6.1.12-lts, 
from 6.2 before 6.2.8-lts, 
from 6.3 before 6.3.3-r2;

This issue affects Session Smart Conductor:

from 5.6.7 before 5.6.17, 
from 6.0.8,
from 6.1 before 6.1.12-lts, 
from 6.2 before 6.2.8-lts, 
from 6.3 before 6.3.3-r2;

This issue affects WAN Assurance Managed Routers:

from 5.6.7 before 5.6.17, 
from 6.0.8,
from 6.1 before 6.1.12-lts, 
from 6.2 before 6.2.8-lts, 
from 6.3 before 6.3.3-r2.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability. This issue was found during internal product security testing or research Solution

The following software releases have been updated to resolve this issue:

Session Smart Router: SSR-5.6.17, SSR-6.1.12-lts, SSR-6.2.8-lts, SSR-6.3.3-r2 and subsequent releases.

It is suggested to upgrade all affected systems to one of these versions of software. In a Conductor-managed deployment, it is sufficient to upgrade only the Conductor nodes and the fix will be applied automatically to all connected routers. As practical, the routers should still be upgraded to a fixed version however they will not be vulnerable once they connect to an upgraded Conductor. Router patching can be confirmed once the router reaches the “running" (on 6.2 and earlier) or “synchronized” (on 6.3+) state on the Conductor".

This vulnerability has been patched automatically on devices that operate with WAN Assurance (where configuration is also managed) connected to the Mist Cloud. As practical, the routers should still be upgraded to a version containing the fix.

It is important to note that when the fix is applied automatically on routers managed by a Conductor or on WAN assurance, it will have no impact on data-plane functions of the router. The application of the fix is non-disruptive to production traffic. There may be a momentary downtime (less than 30 seconds) to the web-based management and APIs.

This issue is being tracked as I95-59677.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL). Workaround

There are no known workarounds for this issue. Severity Assessment Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories." Modification History

2024-02-11: Initial Publication

Related Information

KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process
KB16765: In which releases are vulnerabilities fixed?
KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories
Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team

Restricted Views backed objects (OSV1) could be bypassed under specific circumstances due to a software bug, this could have allowed users that didn't have permission to see such objects to view them via Object Explorer directly. The affected service have been patched and automatically deployed to all Apollo-managed Foundry instances.

Threat actors started exploiting a recent SonicWall firewall vulnerability this week, shortly after proof-of-concept (PoC) code targeting it was published.

According to Bishop Fox, approximately 4,500 internet-facing SonicWall SSL VPN servers had not been patched against CVE-2024-53704 by February 7.

UPDATE: Fortinet has informed us that the new CVE-2025-24472 flaw added to FG-IR-24-535 today is not a zero-day and was already fixed in January, but not disclosed then.

Furthermore, even though the current advisory states that the listed flaws were exploited in attacks and includes workarounds, Fortinet says that only CVE-2024-55591, and not CVE-2025-24472.

It appears that this new CVE is for a different pathway to exploiting the bug that was not previously disclosed and was just now added to the Fortinet advisory about the active exploitation of CVE-2024-55591, causing the confusion.

We have updated this previous toot, changed the title of our article, and added an update to prevent confusion.

Ref: https://infosec.exchange/@BleepingComputer/113986777248862223