• 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

SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 55

 | 

Security Affairs newsletter Round 534 by Pierluigi Paganini – INTERNATIONAL EDITION

 | 

Law enforcement operations seized BlackSuit ransomware gang’s darknet sites

 | 

Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme

 | 

Operation CargoTalon targets Russia’s aerospace with EAGLET malware,

 | 

Unpatched flaw in EoL LG LNV5110R cameras lets hackers gain Admin access

 | 

Koske, a new AI-Generated Linux malware appears in the threat landscape

 | 

Mitel patches critical MiVoice MX-ONE Auth bypass flaw

 | 

Coyote malware is first-ever malware abusing Windows UI Automation

 | 

SonicWall fixed critical flaw in SMA 100 devices exploited in Overstep malware attacks

 | 

DSPM & AI Are Booming: $17.87B and $4.8T Markets by 2033

 | 

Stealth backdoor found in WordPress mu-Plugins folder

 | 

U.S. CISA adds CrushFTP, Google Chromium, and SysAid flaws to its Known Exploited Vulnerabilities catalog

 | 

U.S. CISA urges FCEB agencies to fix two Microsoft SharePoint flaws immediately and added them to its Known Exploited Vulnerabilities catalog

 | 

Sophos fixed two critical Sophos Firewall vulnerabilities

 | 

French Authorities confirm XSS.is admin arrested in Ukraine

 | 

Microsoft linked attacks on SharePoint flaws to China-nexus actors

 | 

Cisco confirms active exploitation of ISE and ISE-PIC flaws

 | 

SharePoint under fire: new ToolShell attacks target enterprises

 | 

CrushFTP zero-day actively exploited at least since July 18

 | 
  • 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
  • Approximately 2000 Citrix NetScaler servers were backdoored in a massive campaign

Approximately 2000 Citrix NetScaler servers were backdoored in a massive campaign

Pierluigi Paganini August 16, 2023

A threat actor has compromised roughly 2,000 Citrix NetScaler servers exploiting a remote code execution tracked as CVE-2023-3519.

In July Citrix warned customers of a critical vulnerability, tracked as CVE-2023-3519 (CVSS score: 9.8), in NetScaler Application Delivery Controller (ADC) and Gateway that is being actively exploited in the wild

The vulnerability CVE-2023-3519 (CVSS score: 9.8) is a code injection that could result in unauthenticated remote code execution. The IT giant warns of the availability of exploits for this vulnerability that have been observed in attacks against unmitigated appliances. 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.

Now, NCC Group researchers warned of an ongoing massive campaign that already compromised more than 1,950 NetScaler instances, while at the time of these attacks, 31127 NetScalers were vulnerable to CVE-2023-3519.

“Fox-IT (part of NCC Group) has uncovered a large-scale exploitation campaign of Citrix NetScalers in a joint effort with the Dutch Institute of Vulnerability Disclosure (DIVD). An adversary appears to have exploited CVE-2023-3519 in an automated fashion, placing webshells on vulnerable NetScalers to gain persistent access.” reads the advisory published by NCC. “The adversary can execute arbitrary commands with this webshell, even when a NetScaler is patched and/or rebooted. At the time of writing, more than 1900 NetScalers remain backdoored.“

Citrix

Using the data supplied by Fox-IT, the Dutch Institute of Vulnerability Disclosure has notified victims.

As of August 14th, 1828 Citrix NetScalers are still compromised, and of the backdoored NetScalers, 1248 are patched for CVE-2023-3519.

“At the time of writing, approximately 69% of the NetScalers that contain a backdoor are not vulnerable anymore to CVE-2023-3519. This indicates that while most administrators were aware of the vulnerability and have since patched their NetScalers to a non-vulnerable version, they have not been (properly) checked for signs of successful exploitation.” continues the report.

The high percentage of patched NetScalers that have been compromised is likely a result of the time at which the campaign took place, between late July 20th and early July 21st.

As of August 14, most of the backdoored instances are in Germany, France and Switzerland.

Citrix

“CVE-2023-3519 was exploited in targeted attacks before a patch was available and was later exploited on a large scale. System administrators need to be aware that adversaries can exploit edge devices to place backdoors that persist even after updates and / or reboots.” concludes the report.”As of now, it is strongly advised to check NetScalers, even if they have been patched and updated to the latest version.”

Mandiant this week released a tool to help organizations scan their Citrix appliances for evidence of post-exploitation activity related to CVE-2023-3519. The tool contains indicators of compromise (IOCs) collected during Mandiant investigations and sourced from our partners and the community. Head over to the Mandiant GitHub page to download the tool today to scan your appliances.

Follow me on Twitter: @securityaffairs and Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, NetScaler)


facebook linkedin twitter

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

you might also like

Pierluigi Paganini July 27, 2025
SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 55
Read more
Pierluigi Paganini July 27, 2025
Security Affairs newsletter Round 534 by Pierluigi Paganini – INTERNATIONAL EDITION
Read more

leave a comment

newsletter

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

    recent articles

    SECURITY AFFAIRS MALWARE NEWSLETTER ROUND 55

    Malware / July 27, 2025

    Security Affairs newsletter Round 534 by Pierluigi Paganini – INTERNATIONAL EDITION

    Breaking News / July 27, 2025

    Law enforcement operations seized BlackSuit ransomware gang’s darknet sites

    Cyber Crime / July 26, 2025

    Arizona woman sentenced for aiding North Korea in U.S. IT job fraud scheme

    Intelligence / July 26, 2025

    Operation CargoTalon targets Russia’s aerospace with EAGLET malware,

    Intelligence / July 25, 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