• 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

Cisco removed the backdoor account from its Unified Communications Manager

 | 

U.S. Sanctions Russia's Aeza Group for aiding crooks with bulletproof hosting

 | 

Qantas confirms customer data breach amid Scattered Spider attacks

 | 

CVE-2025-6554 is the fourth Chrome zero-day patched by Google in 2025

 | 

U.S. CISA adds TeleMessage TM SGNL flaws to its Known Exploited Vulnerabilities catalog

 | 

A sophisticated cyberattack hit the International Criminal Court

 | 

Esse Health data breach impacted 263,000 individuals

 | 

Europol dismantles €460M crypto scam targeting 5,000 victims worldwide

 | 

CISA and U.S. Agencies warn of ongoing Iranian cyber threats to critical infrastructure

 | 

U.S. CISA adds Citrix NetScaler flaw to its Known Exploited Vulnerabilities catalog

 | 

Canada bans Hikvision over national security concerns

 | 

Denmark moves to protect personal identity from deepfakes with new copyright law

 | 

Ahold Delhaize data breach affected over 2.2 Million individuals

 | 

Facebook wants access to your camera roll for AI photo edits

 | 

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 51

 | 

Security Affairs newsletter Round 530 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

The FBI warns that Scattered Spider is now targeting the airline sector

 | 

LapDogs: China-nexus hackers Hijack 1,000+ SOHO devices for espionage

 | 

Taking over millions of developers exploiting an Open VSX Registry flaw

 | 

OneClik APT campaign targets energy sector with stealthy backdoors

 | 
  • 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
  • Hacking
  • Malware
  • Hackers already installed web shells on 581 Citrix servers in CVE-2023-3519 attacks

Hackers already installed web shells on 581 Citrix servers in CVE-2023-3519 attacks

Pierluigi Paganini August 02, 2023

Researchers warn that hundreds of Citrix servers have been hacked in an ongoing campaign exploiting the RCE CVE-2023-3519.

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.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) recently warned of cyber attacks against Citrix NetScaler Application Delivery Controller (ADC) and Gateway devices exploiting the zero-day CVE-2023-3519. The Agency revealed that threat actors targeted a NetScaler ADC appliance deployed in the network of a critical infrastructure organization.

Citrix last week warned customers that the CVE-2023-3519 (CVSS score: 9.8) in NetScaler Application Delivery Controller (ADC) and Gateway is being actively exploited in the wild.

The vulnerability is a code injection that could result in unauthenticated remote code execution. The company added that successful exploitation requires that the appliance is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

“Exploits of CVE-2023-3519 on unmitigated appliances have been observed. Cloud Software Group strongly urges affected customers of NetScaler ADC and NetScaler Gateway to install the relevant updated versions as soon as possible.” reads the report published by Citrix.

The Citrix Cloud Software Group is strongly urging affected customers to install the relevant updated versions as soon as possible. 

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

“The Cybersecurity and Infrastructure Security Agency (CISA) released a Cybersecurity Advisory (CSA), Threat Actors Exploiting Citrix CVE-2023-3519 to Implant Webshells, to warn organizations about threat actors exploiting CVE-2023-3519, an unauthenticated remote code execution (RCE) vulnerability affecting NetScaler (formerly Citrix) Application Delivery Controller (ADC) and NetScaler Gateway.” reads the advisory published by CISA. “In June 2023, threat actors exploited this vulnerability as a zero-day to drop a webshell on a critical infrastructure organization’s NetScaler ADC appliance. The webshell enabled the actors to perform discovery on the victim’s active directory (AD) and collect and exfiltrate AD data. The actors attempted to move laterally to a domain controller but network-segmentation controls for the appliance blocked movement.”

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.

Researchers from the non-profit organization Shadowserver Foundation this initially reported that at least 15,000 Citrix servers were exposed to CVE-2023-3519 attacks based on their version information. Most of the servers are located in the United States and Germany.

Citrix Netscaler ADC

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.

“We continue to report out daily lists of Citrix ADC/Gateway IPs that are known to be compromised with webshells installed (CVE-2023-3519 attacks). We see 581 instances on 2023-08-01.” states the organization.

Heads-up: We continue to report out daily lists of Citrix ADC/Gateway IPs that are known to be compromised with webshells installed (CVE-2023-3519 attacks). We see 581 instances on 2023-08-01.

Data for your network in https://t.co/D1KZAGvfTr

Dashboard: https://t.co/aKOD7zaL1j pic.twitter.com/oqGRwi6ML8

— Shadowserver (@Shadowserver) August 2, 2023

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, Citrix)


facebook linkedin twitter

Citrix CVE-2023-3519 Hacking hacking news information security news IT Information Security malware Pierluigi Paganini Security Affairs Security News

you might also like

Pierluigi Paganini July 02, 2025
Cisco removed the backdoor account from its Unified Communications Manager
Read more
Pierluigi Paganini July 02, 2025
U.S. Sanctions Russia's Aeza Group for aiding crooks with bulletproof hosting
Read more

leave a comment

newsletter

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

    recent articles

    Cisco removed the backdoor account from its Unified Communications Manager

    Security / July 02, 2025

    U.S. Sanctions Russia's Aeza Group for aiding crooks with bulletproof hosting

    Cyber Crime / July 02, 2025

    Qantas confirms customer data breach amid Scattered Spider attacks

    Cyber Crime / July 02, 2025

    CVE-2025-6554 is the fourth Chrome zero-day patched by Google in 2025

    Hacking / July 02, 2025

    U.S. CISA adds TeleMessage TM SGNL flaws to its Known Exploited Vulnerabilities catalog

    Hacking / July 02, 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