Barracuda Email Security Gateway (ESG) hacked via zero-day bug

Barracuda warned customers that some of its Email Security Gateway (ESG) appliances were breached exploiting a zero-day vulnerability.

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.

The vulnerability, tracked as CVE-2023-2868, resides in the module for email attachment screening, the issue was discovered on May 19 and the company fixed it with the release of two security patches on May 20 and 21.

“Barracuda identified a vulnerability (https://nvd.nist.gov/vuln/detail/CVE-2023-2868) in our Email Security Gateway appliance (ESG) on May 19, 2023. A security patch to eliminate the vulnerability was applied to all ESG appliances worldwide on Saturday, May 20, 2023.” reads the advisory published by the security solutions provider. “The vulnerability existed in a module which initially screens the attachments of incoming emails.”

The issue could have a significant impact because the impacted Email Security Gateway (ESG) appliances are used by hundreds of thousands of organizations worldwide, including several high-profile businesses.

The vulnerability doesn’t impact other Barracuda products, the company states that its SaaS email security services is not affected by this issue.

The company investigated the flaw and discovered that it was exploited to target a subset of email gateway appliances. The company notified via the ESG user interface the customers whose appliances they believe were impacted.

“Based on our investigation to date, we’ve identified that the vulnerability resulted in unauthorized access to a subset of email gateway appliances,” continues the advisory. “Users whose appliances we believe were impacted have been notified via the ESG user interface of actions to take. Barracuda has also reached out to these specific customers.“

Barracuda pointed out that the investigation was limited to its ESG product and not the customers’ specific environment. Impacted organizations are recommended to review their networks to determine if other systems were compromised by the attackers.

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Pierluigi Paganini

(SecurityAffairs – hacking, ESG)