Barracuda ESG Breach: A Sophisticated Cyber Espionage Act

The recent Barracuda ESG attack, attributed to the Chinese threat group UNC4841, highlights a sophisticated form of cyber espionage. The group exploited a zero-day vulnerability, showcasing advanced techniques in cyber warfare.


Rapid Response: Barracuda’s Decisive Action Against ESG Vulnerabilities

In response to the CVE-2023-7102 and CVE-2023-7101 vulnerabilities, Barracuda Networks swiftly deployed security updates. Their proactive measures were crucial in mitigating the impact of these serious vulnerabilities on ESG devices.


Rising Ransomware Attacks: A Global Cybersecurity Concern

This incident is part of a worrying global trend of increasing ransomware attacks. Such attacks underscore the critical need for heightened cybersecurity awareness and preparedness across various sectors worldwide.

News > Cyber-Attacks > CA-General
By Kevin Wood

The Rising Menace of Ransomware Attacks and Recent Barracuda ESG Zero-Day Exploitation




The cybersecurity world is once again on high alert following the recent discovery of a zero-day vulnerability in Barracuda Networks’ Email Security Gateway (ESG) appliances. Tracked as CVE-2023-7102, this flaw was actively exploited by Chinese threat actors, identified as UNC4841, to deploy malware backdoors on a limited number of devices.

The Attack and Its Implications

UNC4841, a group linked to China and known for its cyber espionage activities, exploited an arbitrary code execution vulnerability in the open-source Spreadsheet::ParseExcel library used by Barracuda’s Amavis virus scanner. This attack vector allowed the threat actors to send malicious Excel email attachments to targeted ESG devices, compromising their security. The severity of the flaw was underscored by its CVSSv2 score of 7.5 and a CVSS3 score of 8.8, highlighting the significant risk it posed.

Barracuda, in collaboration with Mandiant, responded promptly to this threat. On December 21, 2023, a security update was deployed to all active ESGs to address the vulnerability, automatically applied without customer intervention. The update aimed to fortify the devices against the CVE-2023-7102 vulnerability and included measures against new variants of the Seaspy and Saltwater malware used in the attack.

Additionally, Barracuda issued a warning regarding another vulnerability, CVE-2023-7101, within the same library. Although there was no evidence of exploitation, the unpatched nature of this flaw necessitated vigilance and proactive measures by organizations using the affected library.

The Broader Context of Ransomware Attacks

The exploitation of the Barracuda ESG vulnerability is part of a larger and more concerning trend in cyber threats – ransomware attacks. These attacks have become increasingly sophisticated and damaging, targeting a wide range of sectors, including healthcare, finance, and government institutions. The method of using zero-day vulnerabilities for deploying ransomware and backdoors highlights the adaptability and persistence of threat actors like UNC4841.

Ransomware attacks not only compromise sensitive data but also disrupt critical services and operations, leading to significant financial losses and reputational damage. The global reach of such attacks, as evidenced by UNC4841 targeting entities across 16 countries, underscores the need for robust cybersecurity measures and international cooperation to combat these threats.


The incident involving Barracuda’s ESG appliances serves as a stark reminder of the evolving nature of cyber threats and the importance of vigilance and proactive cybersecurity practices. As ransomware attacks continue to pose a significant challenge globally, organizations must stay informed and prepared to counter these sophisticated threats.