Russian-Linked Hackers Target 80+ Organizations via Roundcube Flaws

Threat actors operating with interests aligned to Belarus and Russia have been linked to a new cyber espionage campaign that likely exploited cross-site scripting (XSS) vulnerabilities in Roundcube webmail servers to target over 80 organizations. These entities are primarily located in Georgia, Poland, and Ukraine, according to Recorded Future, which attributed the intrusion set to a threat

Zero-Day Flaw in Zimbra Email Software Exploited by Four Hacker Groups

A zero-day flaw in the Zimbra Collaboration email software was exploited by four different groups in real-world attacks to pilfer email data, user credentials, and authentication tokens. "Most of this activity occurred after the initial fix became public on GitHub," Google Threat Analysis Group (TAG) said in a report shared with The Hacker News. The flaw, tracked as CVE-2023-37580 (CVSS score:

S3 Ep144: When threat hunting goes down a rabbit hole

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Zimbra Collaboration Suite warning: Patch this 0-day right now (by hand)!

Zimbra didn't actually say, "Do not delay/Do it today," but they did say, "We kindly request your cooperation to apply the fix manually."

Zimbra Warns of Critical Zero-Day Flaw in Email Software Amid Active Exploitation

Zimbra has warned of a critical zero-day security flaw in its email software that has come under active exploitation in the wild. "A security vulnerability in Zimbra Collaboration Suite Version 8.8.15 that could potentially impact the confidentiality and integrity of your data has surfaced," the company said in an advisory. It also said that the issue has been addressed and that it's expected to

Winter Vivern APT Targets European Government Entities with Zimbra Vulnerability

The advanced persistent threat (APT) actor known as Winter Vivern is now targeting officials in Europe and the U.S. as part of an ongoing cyber espionage campaign. "TA473 since at least February 2023 has continuously leveraged an unpatched Zimbra vulnerability in publicly facing webmail portals that allows them to gain access to the email mailboxes of government entities in Europe," Proofpoint 

Zimbra Releases Patch for Actively Exploited Vulnerability in its Collaboration Suite

Zimbra has released patches to contain an actively exploited security flaw in its enterprise collaboration suite that could be leveraged to upload arbitrary files to vulnerable instances. Tracked as CVE-2022-41352 (CVSS score: 9.8), the issue affects a component of the Zimbra suite called Amavis, an open source content filter, and more specifically, the cpio utility it uses to scan and extract

Hackers Exploiting Unpatched RCE Flaw in Zimbra Collaboration Suite

A severe remote code execution vulnerability in Zimbra's enterprise collaboration software and email platform is being actively exploited, with no patch currently available to remediate the issue. The shortcoming, assigned CVE-2022-41352, carries a critical-severity rating of CVSS 9.8, providing a pathway for attackers to upload arbitrary files and carry out malicious actions on affected

Microsoft: Two New 0-Day Flaws in Exchange Server

Microsoft Corp. is investigating reports that attackers are exploiting two previously unknown vulnerabilities in Exchange Server, a technology many organizations rely on to send and receive email. Microsoft says it is expediting work on software patches to plug the security holes. In the meantime, it is urging a subset of Exchange customers to enable a setting that could help mitigate ongoing attacks.

In customer guidance released Thursday, Microsoft said it is investigating two reported zero-day flaws affecting Microsoft Exchange Server 2013, 2016, and 2019. CVE-2022-41040, is a Server-Side Request Forgery (SSRF) vulnerability that can enable an authenticated attacker to remotely trigger the second zero-day vulnerability — CVE-2022-41082 — which allows remote code execution (RCE) when PowerShell is accessible to the attacker.

Microsoft said Exchange Online has detections and mitigation in place to protect customers. Customers using on-premises Microsoft Exchange servers are urged to review the mitigations suggested in the security advisory, which Microsoft says should block the known attack patterns.

Vietnamese security firm GTSC on Thursday published a writeup on the two Exchange zero-day flaws, saying it first observed the attacks in early August being used to drop “webshells.” These web-based backdoors offer attackers an easy-to-use, password-protected hacking tool that can be accessed over the Internet from any browser.

“We detected webshells, mostly obfuscated, being dropped to Exchange servers,” GTSC wrote. “Using the user-agent, we detected that the attacker uses Antsword, an active Chinese-based opensource cross-platform website administration tool that supports webshell management. We suspect that these come from a Chinese attack group because the webshell codepage is 936, which is a Microsoft character encoding for simplified Chinese.”

GTSC’s advisory includes details about post-compromise activity and related malware, as well as steps it took to help customers respond to active compromises of their Exchange Server environment. But the company said it would withhold more technical details of the vulnerabilities for now.

In March 2021, hundreds of thousands of organizations worldwide had their email stolen and multiple backdoor webshells installed, all thanks to four zero-day vulnerabilities in Exchange Server.

Granted, the zero-day flaws that powered that debacle were far more critical than the two detailed this week, and there are no signs yet that exploit code has been publicly released (that will likely change soon). But part of what made last year’s Exchange Server mass hack so pervasive was that vulnerable organizations had little or no advance notice on what to look for before their Exchange Server environments were completely owned by multiple attackers.

Microsoft is quick to point out that these zero-day flaws require an attacker to have a valid username and password for an Exchange user, but this may not be such a tall order for the hackers behind these latest exploits against Exchange Server.

Steven Adair is president of Volexity, the Virginia-based cybersecurity firm that was among the first to sound the alarm about the Exchange zero-days targeted in the 2021 mass hack. Adair said GTSC’s writeup includes an Internet address used by the attackers that Volexity has tied with high confidence to a China-based hacking group that has recently been observed phishing Exchange users for their credentials.

In February 2022, Volexity warned that this same Chinese hacking group was behind the mass exploitation of a zero-day vulnerability in the Zimbra Collaboration Suite, which is a competitor to Microsoft Exchange that many enterprises use to manage email and other forms of messaging.

If your organization runs Exchange Server, please consider reviewing the Microsoft mitigations and the GTSC post-mortem on their investigations.

Researchers Warn of Ongoing Mass Exploitation of Zimbra RCE Vulnerability

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Thursday added two flaws to its Known Exploited Vulnerabilities Catalog, citing evidence of active exploitation. The two high-severity issues relate to weaknesses in Zimbra Collaboration, both of which could be chained to achieve unauthenticated remote code execution on affected email servers - CVE-2022-27925 (CVSS score: 7.2)

CISA Adds Zimbra Email Vulnerability to its Exploited Vulnerabilities Catalog

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Thursday added a recently disclosed high-severity vulnerability in the Zimbra email suite to its Known Exploited Vulnerabilities Catalog, citing evidence of active exploitation. The issue in question is CVE-2022-27924 (CVSS score: 7.5), a command injection flaw in the platform that could lead to the execution of arbitrary

New UnRAR Vulnerability Could Let Attackers Hack Zimbra Webmail Servers

A new security vulnerability has been disclosed in RARlab's UnRAR utility that, if successfully exploited, could permit a remote attacker to execute arbitrary code on a system that relies on the binary. The flaw, assigned the identifier CVE-2022-30333, relates to a path traversal vulnerability in the Unix versions of UnRAR that can be triggered upon extracting a maliciously crafted RAR archive.

New Zimbra Email Vulnerability Could Let Attackers Steal Your Login Credentials

A new high-severity vulnerability has been disclosed in the Zimbra email suite that, if successfully exploited, enables an unauthenticated attacker to steal cleartext passwords of users sans any user interaction. "With the consequent access to the victims' mailboxes, attackers can potentially escalate their access to targeted organizations and gain access to various internal services and steal