• Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
MUST READ

Qilin ransomware claimed responsibility for the attack on the beer giant Asahi

 | 

DragonForce, LockBit, and Qilin, a new triad aims to dominate the ransomware landscape

 | 

DraftKings thwarts credential stuffing attack, but urges password reset and MFA

 | 

Redis patches 13-Year-Old Lua flaw enabling Remote Code Execution

 | 

U.S. CISA adds Synacor Zimbra Collaboration Suite (ZCS) flaw to its Known Exploited Vulnerabilities catalog

 | 

GoAnywhere MFT zero-day used by Storm-1175 in Medusa ransomware campaigns

 | 

CrowdStrike ties Oracle EBS RCE (CVE-2025-61882) to Cl0p attacks began Aug 9, 2025

 | 

Discord discloses third-party breach affecting customer support data

 | 

Oracle patches critical E-Business Suite flaw exploited by Cl0p hackers

 | 

LinkedIn sues ProAPIs for $15K/Month LinkedIn data scraping scheme

 | 

Zimbra users targeted in zero-day exploit using iCalendar attachments

 | 

Reading the ENISA Threat Landscape 2025 report

 | 

Ghost in the Cloud: Weaponizing AWS X-Ray for Command & Control

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 65

 | 

Security Affairs newsletter Round 544 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

GreyNoise detects 500% surge in scans targeting Palo Alto Networks portals

 | 

U.S. CISA adds Smartbedded Meteobridge, Samsung, Juniper ScreenOS, Jenkins, and GNU Bash flaws to its Known Exploited Vulnerabilities catalog

 | 

ShinyHunters Launches Data Leak Site: Trinity of Chaos Announces New Ransomware Victims

 | 

ProSpy, ToSpy malware pose as Signal and ToTok to steal data in UAE

 | 

Google warns of Cl0p extortion campaign against Oracle E-Business users

 | 
  • Home
  • Cyber Crime
  • Cyber warfare
  • APT
  • Data Breach
  • Deep Web
  • Digital ID
  • Hacking
  • Hacktivism
  • Intelligence
  • Internet of Things
  • Laws and regulations
  • Malware
  • Mobile
  • Reports
  • Security
  • Social Networks
  • Terrorism
  • ICS-SCADA
  • POLICIES
  • Contact me
  • Home
  • Breaking News
  • Cyber Crime
  • Hacking
  • FIN8-linked actor targets Citrix NetScaler systems

FIN8-linked actor targets Citrix NetScaler systems

Pierluigi Paganini August 29, 2023

A financially motivated actor linked to the FIN8 group exploits the CVE-2023-3519 RCE in attacks on Citrix NetScaler systems in massive attacks.

Sophos X-Ops is tracking an ongoing campaign, which is targeting Citrix NetScaler systems, conducted by threat actors linked to the FIN8 group [BleepingComputer, SOCRadar]. The hackers are exploiting the remote code execution, tracked as CVE-2023-3519, in a large-scale campaign.

The flaw CVE-2023-3519 (CVSS score: 9.8) is a code injection that could result in unauthenticated remote code execution. Exploits for this vulnerability have been observed in attacks against unmitigated appliances. Citrix reported that successful exploitation requires that the appliance is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

Sophos X-Ops is currently tracking a campaign by threat actors targeting unpatched Citrix NetScaler systems exposed to the internet. Our data indicates strong similarity between attacks using CVE-2023-3519 and previous attacks using a number of the same TTPs.

— Sophos X-Ops (@SophosXOps) August 25, 2023

Sophos started monitoring this campaign in mid-August when they first spotted threat actors infecting a target system using the Critical-class NetScaler vulnerability as a code-injection tool to conduct a domain-wide attack.

The attackers use highly obfuscated PowerShell scripts called with distinctive arguments, they were also spotted dropping randomly named PHP webshells (/var/vpn/theme/[random].php) on victim machines.

“The injected payload for the attack we saw involving Citrix is still under analysis. However, earlier in the summer, we saw activity in a second case that bore a strong resemblance to this case.” continues Sophos.

In July, the U.S. CISA revealed that threat actors are exploiting the vulnerability to drop web shells on vulnerable systems.

CISA did not attribute the attack to a specific threat actor. The attackers exploited the flaw to deploy the the webshell that was used to perform discovery on the victim’s active directory (AD) and collect and exfiltrate AD data. The threat actors attempted to move laterally to a domain controller, but CISA pointed out that network-segmentation controls for the appliance blocked movement.

The attackers obtained encrypted passwords from NetScaler ADC configuration files, and the decryption key was stored on the ADC appliance. Then threat actors sent data as an image file to a web-accessible path: 

cp /var/tmp/test.tar.gz /netscaler/ns_gui/vpn/medialogininit.png.

The attackers attempted to verify outbound network connectivity with a ping command and executed host commands for a subnet-wide DNS lookup. Network-segmentation controls blocked this activity too.

In early August, security researchers from the non-profit organization Shadowserver Foundation reported that hundreds of Citrix Netscaler ADC and Gateway servers have already been compromised as part of an ongoing campaign exploiting the critical remote code execution (RCE) vulnerability CVE-2023-3519.

In an update provided by Shadowserver Foundation, the researchers from the non-profit organization confirmed that threat actors successfully installed webshells on at least 581 Citrix servers compromised by exploiting the above issue.

Earlier in the summer, Sophos saw activity that didn’t involve the Citrix vulnerability, but that shared TTP similarities (domain discovery, plink, BlueVPS hosting, unusual PowerShell scripting, use of PuTTY Secure Copy [pscp]) with attacks conducted by a known threat actor specializing in ransomware attacks.

Threat actors also use a C2 IP address (45.66.248[.]189) for malware staging and a second C2 IP (85.239.53[.]49) responding to the same C2 software. These C2 addresses were also observed in the previous ransomware attacks.

Sophos tracked these malicious activities as Threat Activity Cluster number STAC4663.

The researchers are still analyzing the payload delivered in the attacks, which is injected into “wuauclt.exe” or “wmiprvse.exe.”

“We advise anyone with Citrix NetScaler infrastructure to immediately check it for signs of compromise and also to patch the vulnerability. Patching alone won’t address attacks already using the vuln to gain access to the system so both actions are necessary for proper protection.” continues the report.

Sophos also shared a list of IoCs for this campaign:

A list of IoCs for this case are available on our Github.https://t.co/hLl0GSvEWj Citrix CVE-2023-3519 attacks.csv

— Sophos X-Ops (@SophosXOps) August 25, 2023

The FIN8 group has been active since 2016, it leverages known malware such as PUNCHTRACK and BADHATCH to infect PoS systems and steal payment card data.

In the past few years, the group has been observed using a number of ransomware threats, including the Ragnar Locker ransomware (June 2021), and the White Rabbit ransomware (January 2022).

On December 2022, Symantec observed the group attempting to deploy the ALPHV/BlackCat ransomware.

Sophos has published a list of IoCs (indicators of compromise) for this campaign on GitHub to help defenders detect and stop the threat.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, Citrix NetScaler)


facebook linkedin twitter

Citrix NetScaler Cybercrime FIN8 Hacking hacking news information security news IT Information Security Pierluigi Paganini ransomware Security Affairs Security News

you might also like

Pierluigi Paganini October 08, 2025
Qilin ransomware claimed responsibility for the attack on the beer giant Asahi
Read more
Pierluigi Paganini October 08, 2025
DragonForce, LockBit, and Qilin, a new triad aims to dominate the ransomware landscape
Read more

leave a comment

newsletter

Subscribe to my email list and stay
up-to-date!

    recent articles

    Qilin ransomware claimed responsibility for the attack on the beer giant Asahi

    Cyber Crime / October 08, 2025

    DragonForce, LockBit, and Qilin, a new triad aims to dominate the ransomware landscape

    Cyber Crime / October 08, 2025

    DraftKings thwarts credential stuffing attack, but urges password reset and MFA

    Security / October 08, 2025

    Redis patches 13-Year-Old Lua flaw enabling Remote Code Execution

    Security / October 08, 2025

    U.S. CISA adds Synacor Zimbra Collaboration Suite (ZCS) flaw to its Known Exploited Vulnerabilities catalog

    Hacking / October 07, 2025

    To contact me write an email to:

    Pierluigi Paganini :
    pierluigi.paganini@securityaffairs.co

    LEARN MORE

    QUICK LINKS

    • Home
    • Cyber Crime
    • Cyber warfare
    • APT
    • Data Breach
    • Deep Web
    • Digital ID
    • Hacking
    • Hacktivism
    • Intelligence
    • Internet of Things
    • Laws and regulations
    • Malware
    • Mobile
    • Reports
    • Security
    • Social Networks
    • Terrorism
    • ICS-SCADA
    • POLICIES
    • Contact me

    Copyright@securityaffairs 2024

    We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By clicking “Accept All”, you consent to the use of ALL the cookies. However, you may visit "Cookie Settings" to provide a controlled consent.
    Cookie SettingsAccept All
    Manage consent

    Privacy Overview

    This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities...
    Necessary
    Always Enabled
    Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
    Non-necessary
    Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
    SAVE & ACCEPT