• 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

Malicious AI-generated npm package hits Solana users

 | 

Meta Offers $1M bounty at Pwn2Own Ireland 2025 for WhatsApp exploits

 | 

ToolShell under siege: Check Point analyzes Chinese APT Storm-2603

 | 

CISA released Thorium platform to support malware and forensic analysis

 | 

Russia-linked APT Secret Blizzard targets foreign embassies in Moscow with ApolloShadow malware

 | 

Dahua Camera flaws allow remote hacking. Update firmware now

 | 

Researchers released a decryptor for the FunkSec ransomware

 | 

Apple fixed a zero-day exploited in attacks against Google Chrome users

 | 

PyPI maintainers alert users to email verification phishing attack

 | 

FBI seizes 20 BTC from Chaos Ransomware affiliate targeting Texas firms

 | 

Critical SAP flaw exploited to launch Auto-Color Malware attack on U.S. company

 | 

Orange reports major cyberattack, warns of service disruptions

 | 

Hackers leak images and comments from women dating safety app Tea

 | 

Pro-Ukraine hacktivists claim cyberattack on Russian Airline Aeroflot that caused the cancellation of +100 flights

 | 

Seychelles Commercial Bank Reported Cybersecurity Incident

 | 

Microsoft uncovers macOS flaw allowing bypass TCC protections and exposing sensitive data

 | 

U.S. CISA adds Cisco ISE and PaperCut NG/MF flaws to its Known Exploited Vulnerabilities catalog

 | 

Critical WordPress Post SMTP plugin flaw exposes 200K+ sites to full takeover

 | 

Scattered Spider targets VMware ESXi in using social engineering

 | 

China-linked group Fire Ant exploits VMware and F5 flaws since early 2025

 | 
  • 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
  • CISA warns about SUBMARINE Backdoor employed in Barracuda ESG attacks

CISA warns about SUBMARINE Backdoor employed in Barracuda ESG attacks

Pierluigi Paganini July 29, 2023

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) warns of threat actors deploying the SUBMARINE Backdoor in Barracuda ESG attacks.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) published an alert on a malware variant, tracked as SUBMARINE Backdoor, that was employed in attacks exploiting the flaw CVE-2023-2868 in Barracuda Email Security Gateway (ESG) appliances.

The vulnerability CVE-2023-2868 resides in the module for email attachment screening, threat actors exploited the flaw to obtain unauthorized access to a subset of ESG appliances.

“SUBMARINE is a novel persistent backdoor executed with root privileges that lives in a Structured Query Language (SQL) database on the ESG appliance. SUBMARINE comprises multiple artifacts—including a SQL trigger, shell scripts, and a loaded library for a Linux daemon—that together enable execution with root privileges, persistence, command and control, and cleanup.” reads the alert. “CISA also analyzed artifacts related to SUBMARINE that contained the contents of the compromised SQL database.”

CISA warns that the backdoor can be used by attackers for lateral movement.

At the end of May, the network security solutions provider Barracuda warned customers that some of its Email Security Gateway (ESG) appliances were recently breached by threat actors exploiting a now-patched zero-day vulnerability.

In Mid-June, Mandiant researchers linked the threat actor UNC4841 behind the attacks that exploited the recently patched Barracuda ESG zero-day vulnerability to China.

“Through the investigation, Mandiant identified a suspected China-nexus actor, currently tracked as UNC4841, targeting a subset of Barracuda ESG appliances to utilize as a vector for espionage, spanning a multitude of regions and sectors.” reads the report published by Mandiant. “Mandiant assesses with high confidence that UNC4841 is an espionage actor behind this wide-ranging campaign in support of the People’s Republic of China.

As per the vendor’s statement, the flaw has been exploited in real-world scenarios, with incidents dating back to October 2022 at the very least. Barracuda, with the support of Mandiant, discovered the issue was exploited to deploy malware on a subset of appliances allowing for persistent backdoor access.

The families of malware employed in the attacks are:

  • SALTWATER – A malware-laced module for the Barracuda SMTP daemon (bsmtpd) that supports multiple capabilities such as uploading/downloading arbitrary files, executing commands, as well as proxying and tunneling malicious traffic to avoid detection. The backdoor component is constructed by leveraging hooks on the send, recv, and close system calls, comprising a total of five distinct components referred to as “Channels” within the binary.
  • SEASPY – An x64 ELF persistent backdoor masquerades as a legitimate Barracuda Networks service and posing itself as a PCAP filter, specifically monitoring traffic on port 25 (SMTP). SEASPY also supports backdoor functionality that is activated by a “magic packet”.
  • SEASIDE is a module written in Lua for bsmtpd, it establishes a reverse shell via SMTP HELO/EHLO commands sent via the malware’s C2 server.

SUBMARINE resides in a Structured Query Language (SQL) database on the Barracuda ESG appliance, it is executed with root privileges.

CISA’s Malware Analysis Report (MAR) includes technical details about the backdoor, including Indicators of Compromise (IoCs) and Yara Rule for its detection.

Follow me on Twitter: @securityaffairs Facebook and Mastodon

Pierluigi Paganini

(SecurityAffairs – hacking, Barracuda ESG)


facebook linkedin twitter

Barracuda ESG CVE-2023-2868 Hacking hacking news information security news IT Information Security malware Pierluigi Paganini Security Affairs Security News SUBMARINE Backdoor

you might also like

Pierluigi Paganini August 01, 2025
Malicious AI-generated npm package hits Solana users
Read more
Pierluigi Paganini August 01, 2025
Meta Offers $1M bounty at Pwn2Own Ireland 2025 for WhatsApp exploits
Read more

leave a comment

newsletter

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

    recent articles

    Malicious AI-generated npm package hits Solana users

    Malware / August 01, 2025

    Meta Offers $1M bounty at Pwn2Own Ireland 2025 for WhatsApp exploits

    Hacking / August 01, 2025

    ToolShell under siege: Check Point analyzes Chinese APT Storm-2603

    APT / August 01, 2025

    CISA released Thorium platform to support malware and forensic analysis

    Cyber Crime / August 01, 2025

    Russia-linked APT Secret Blizzard targets foreign embassies in Moscow with ApolloShadow malware

    APT / July 31, 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