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The Hacker News - Cybersecurity News and Analysis: Microsoft Exchange

New Incident Report Reveals How Hive Ransomware Targets Organizations

New Incident Report Reveals How Hive Ransomware Targets Organizations

April 21, 2022Ravie Lakshmanan
A recent Hive ransomware attack carried out by an affiliate involved the exploitation of "ProxyShell" vulnerabilities in the Microsoft Exchange Server that were disclosed last year to encrypt an unnamed customer's network. "The actor managed to achieve its malicious goals and encrypt the environment in less than 72 hours from the initial compromise," Varonis security researcher, Nadav Ovadia,  said  in a post-mortem analysis of the incident.  Hive, which was  first observed  in June 2021, follows the lucrative ransomware-as-a-service (RaaS) scheme adopted by other cybercriminal groups in recent years, enabling affiliates to deploy the file-encrypting malware after gaining a foothold into their victims' networks. ProxyShell  — tracked as CVE-2021-31207, CVE-2021-34523, and CVE-2021-34473 — involves a combination of security feature bypass, privilege escalation, and remote code execution in the Microsoft Exchange Server, effectively granting the attacker
Microsoft Issues Patches for 2 Windows Zero-Days and 126 Other Vulnerabilities

Microsoft Issues Patches for 2 Windows Zero-Days and 126 Other Vulnerabilities

April 12, 2022Ravie Lakshmanan
Microsoft's Patch Tuesday updates for the month of April have addressed a  total of 128 security vulnerabilities  spanning across its software product portfolio, including Windows, Defender, Office, Exchange Server, Visual Studio, and Print Spooler, among others. 10 of the 128 bugs fixed are rated Critical, 115 are rated Important, and three are rated Moderate in severity, with one of the flaws listed as publicly known and another under active attack at the time of the release. The updates are in addition to  26 other flaws  resolved by Microsoft in its Chromium-based Edge browser since the start of the month. The actively exploited flaw ( CVE-2022-24521 , CVSS score: 7.8) relates to an elevation of privilege vulnerability in the Windows Common Log File System (CLFS). Credited with reporting the flaw are the U.S. National Security Agency (NSA) and CrowdStrike researchers Adam Podlosky and Amir Bazine. The second publicly-known zero-day flaw ( CVE-2022-26904 , CVSS score: 7.0)
Moses Staff Hackers Targeting Israeli Organizations for Cyber Espionage

Moses Staff Hackers Targeting Israeli Organizations for Cyber Espionage

February 16, 2022Ravie Lakshmanan
The politically motivated Moses Staff hacker group has been observed using a custom multi-component toolset with the goal of carrying out espionage against its targets as part of a new campaign that exclusively singles out Israeli organizations. First  publicly documented  in late 2021, Moses Staff is believed to be sponsored by the Iranian government, with attacks reported against entities in Israel, Italy, India, Germany, Chile, Turkey, the U.A.E., and the U.S. Earlier this month, the hacker collective was observed incorporating a previously undocumented remote access trojan (RAT) called " StrifeWater " that masquerades as the Windows Calculator app to evade detection. "Close examination reveals that the group has been active for over a year, much earlier than the group's first official public exposure, managing to stay under the radar with an extremely low detection rate," findings from FortiGuard Labs show . The latest threat activity involves an atta
Hackers Using Malicious IIS Server Module to Steal Microsoft Exchange Credentials

Hackers Using Malicious IIS Server Module to Steal Microsoft Exchange Credentials

December 15, 2021Ravie Lakshmanan
Malicious actors are deploying a previously undiscovered binary, an Internet Information Services ( IIS ) webserver module dubbed " Owowa ," on Microsoft Exchange Outlook Web Access servers with the goal of stealing credentials and enabling remote command execution. "Owowa is a C#-developed .NET v4.0 assembly that is intended to be loaded as a module within an IIS web server that also exposes Exchange's Outlook Web Access (OWA)," Kaspersky researchers Paul Rascagneres and Pierre Delcher  said . "When loaded this way, Owowa will steal credentials that are entered by any user in the OWA login page, and will allow a remote operator to run commands on the underlying server." The idea that a rogue IIS module can be fashioned as a backdoor is not new. In August 2021, an exhaustive study of the IIS threat landscape by Slovak cybersecurity company ESET revealed  as many as 14 malware families that were developed as native IIS modules in an attempt to interc
Microsoft Issues Patches for Actively Exploited Excel, Exchange Server 0-Day Bugs

Microsoft Issues Patches for Actively Exploited Excel, Exchange Server 0-Day Bugs

November 09, 2021Ravie Lakshmanan
Microsoft has released security updates as part of its monthly  Patch Tuesday  release cycle to address 55 vulnerabilities across Windows, Azure, Visual Studio, Windows Hyper-V, and Office, including fixes for two actively exploited zero-day flaws in Excel and Exchange Server that could be abused to take control of an affected system. Of the 55 glitches, six are rated Critical and 49 are rated as Important in severity, with four others listed as publicly known at the time of release.  The most critical of the flaws are  CVE-2021-42321  (CVSS score: 8.8) and  CVE-2021-42292  (CVSS score: 7.8), each concerning a  post-authentication remote code execution flaw  in Microsoft Exchange Server and a security bypass vulnerability impacting Microsoft Excel versions 2013-2021 respectively. The Exchange Server issue is also one of the bugs that was demonstrated at the  Tianfu Cup  held in China last month. However, the Redmond-based tech giant did not provide any details on how the two aforem
Microsoft Exchange Bug Exposes ~100,000 Windows Domain Credentials

Microsoft Exchange Bug Exposes ~100,000 Windows Domain Credentials

September 23, 2021Ravie Lakshmanan
An unpatched design flaw in the implementation of Microsoft Exchange's Autodiscover protocol has resulted in the leak of approximately 100,000 login names and passwords for Windows domains worldwide. "This is a severe security issue, since if an attacker can control such domains or has the ability to 'sniff' traffic in the same network, they can capture domain credentials in plain text (HTTP basic authentication) that are being transferred over the wire," Guardicore's Amit Serper  said  in a technical report. "Moreover, if the attacker has DNS-poisoning capabilities on a large scale (such as a nation-state attacker), they could systematically syphon out leaky passwords through a large-scale DNS poisoning campaign based on these Autodiscover TLDs [top-level domains]." The Exchange  Autodiscover  service enables users to configure applications such as Microsoft Outlook with minimal user input, allowing just a combination of email addresses and pas
New Microsoft Exchange 'ProxyToken' Flaw Lets Attackers Reconfigure Mailboxes

New Microsoft Exchange 'ProxyToken' Flaw Lets Attackers Reconfigure Mailboxes

August 30, 2021Ravie Lakshmanan
Details have emerged about a now-patched security vulnerability impacting Microsoft Exchange Server that could be weaponized by an unauthenticated attacker to modify server configurations, thus leading to the disclosure of Personally Identifiable Information (PII). The issue, tracked as  CVE-2021-33766  (CVSS score: 7.3) and coined " ProxyToken ," was discovered by Le Xuan Tuyen, a researcher at the Information Security Center of Vietnam Posts and Telecommunications Group (VNPT-ISC), and reported through the Zero-Day Initiative (ZDI) program in March 2021. "With this vulnerability, an unauthenticated attacker can perform configuration actions on mailboxes belonging to arbitrary users," the ZDI  said  Monday. "As an illustration of the impact, this can be used to copy all emails addressed to a target and account and forward them to an account controlled by the attacker." Microsoft addressed the issue as part of its  Patch Tuesday updates  for July 2021
WARNING: Microsoft Exchange Under Attack With ProxyShell Flaws

WARNING: Microsoft Exchange Under Attack With ProxyShell Flaws

August 22, 2021Ravie Lakshmanan
The U.S. Cybersecurity and Infrastructure Security Agency is warning of active exploitation attempts that leverage the latest line of " ProxyShell " Microsoft Exchange vulnerabilities that were patched earlier this May, including deploying LockFile ransomware on compromised systems. Tracked as CVE-2021-34473, CVE-2021-34523, and CVE-2021-31207, the vulnerabilities enable adversaries to bypass ACL controls, elevate privileges on the Exchange PowerShell backend, effectively permitting the attacker to perform unauthenticated, remote code execution. While the former two were addressed by Microsoft on April 13, a patch for CVE-2021-31207 was shipped as part of the Windows maker's May Patch Tuesday updates. "An attacker exploiting these vulnerabilities could execute arbitrary code on a vulnerable machine," CISA  said . The development comes a little over a week after cybersecurity researchers sounded the alarm on  opportunistic scanning and exploitation  of unpat
Hackers Actively Searching for Unpatched Microsoft Exchange Servers

Hackers Actively Searching for Unpatched Microsoft Exchange Servers

August 13, 2021Ravie Lakshmanan
Threat actors are actively carrying out opportunistic  scanning  and  exploitation  of Exchange servers using a new exploit chain leveraging a trio of flaws affecting on-premises installations, making them the latest set of bugs after ProxyLogon vulnerabilities were exploited en masse at the start of the year. The remote code execution flaws have been collectively dubbed "ProxyShell." At least 30,000 machines are affected by the vulnerabilities,  according  to a Shodan scan performed by Jan Kopriva of SANS Internet Storm Center. "Started to see in the wild exploit attempts against our honeypot infrastructure for the Exchange ProxyShell vulnerabilities," NCC Group's Richard Warren  tweeted , noting that one of the intrusions resulted in the deployment of a "C# aspx webshell in the /aspnet_client/ directory." Patched in early March 2021,  ProxyLogon  is the moniker for CVE-2021-26855, a server-side request forgery vulnerability in Exchange Server tha
US and Global Allies Accuse China of Massive Microsoft Exchange Attack

US and Global Allies Accuse China of Massive Microsoft Exchange Attack

July 19, 2021Ravie Lakshmanan
The U.S. government and its key allies, including the European Union, the U.K., and NATO, formally attributed the massive cyberattack against Microsoft Exchange email servers to state-sponsored hacking crews working affiliated with the People's Republic of China's Ministry of State Security (MSS). In a  statement  issued by the White House on Monday, the administration said, "with a high degree of confidence that malicious cyber actors affiliated with PRC's MSS conducted cyber-espionage operations utilizing the zero-day vulnerabilities in Microsoft Exchange Server disclosed in early March 2021. The U.K. government  accused  Beijing of a "pervasive pattern of hacking" and "systemic cyber sabotage." The  sweeping espionage campaign  exploited four previously undiscovered vulnerabilities in Microsoft Exchange software and is believed to have hit at least 30,000 organizations in the U.S. and hundreds of thousands more worldwide. Microsoft identified
Prometei Botnet Exploiting Unpatched Microsoft Exchange Servers

Prometei Botnet Exploiting Unpatched Microsoft Exchange Servers

April 23, 2021Ravie Lakshmanan
Attackers are exploiting the ProxyLogon Microsoft Exchange Server flaws to co-opt vulnerable machines to a cryptocurrency botnet named Prometei, according to new research. "Prometei exploits the recently disclosed Microsoft Exchange vulnerabilities associated with the HAFNIUM attacks to penetrate the network for malware deployment, credential harvesting and more," Boston-based cybersecurity firm Cybereason  said  in an analysis summarizing its findings. First documented by Cisco Talos in July 2020,  Prometei  is a multi-modular botnet, with the actor behind the operation employing a wide range of specially-crafted tools and known exploits such as EternalBlue and BlueKeep to harvest credentials, laterally propagate across the network and "increase the amount of systems participating in its Monero-mining pool." "Prometei has both Windows-based and Linux-Unix based versions, and it adjusts its payload based on the detected operating system, on the targeted in
NSA Discovers New Vulnerabilities Affecting Microsoft Exchange Servers

NSA Discovers New Vulnerabilities Affecting Microsoft Exchange Servers

April 13, 2021Ravie Lakshmanan
In its April slate of patches, Microsoft rolled out fixes for a total of  114 security flaws , including an actively exploited zero-day and four remote code execution bugs in Exchange Server. Of the  114 flaws , 19 are rated as Critical, 88 are rated Important, and one is rated Moderate in severity. Chief among them is  CVE-2021-28310 , a privilege escalation vulnerability in Win32k that's said to be under active exploitation, allowing attackers to elevate privileges by running malicious code on a target system.  Cybersecurity firm Kaspersky, which discovered and reported the flaw to Microsoft in February, linked the zero-day exploit to a threat actor named Bitter APT, which was found exploiting a similar flaw ( CVE-2021-1732 ) in attacks late last year. "It is an escalation of privilege (EoP) exploit that is likely used together with other browser exploits to escape sandboxes or get system privileges for further access," Kaspersky researcher Boris Larin  said . NS
Use This One-Click Mitigation Tool from Microsoft to Prevent Exchange Attacks

Use This One-Click Mitigation Tool from Microsoft to Prevent Exchange Attacks

March 15, 2021Ravie Lakshmanan
Microsoft on Monday released a one-click mitigation software that applies all the necessary countermeasures to secure vulnerable environments against the ongoing widespread  ProxyLogon Exchange Server  cyberattacks. Called Exchange On-premises Mitigation Tool ( EOMT ), the PowerShell-based script serves to mitigate against current known attacks using CVE-2021-26855, scan the Exchange Server using the  Microsoft Safety Scanner  for any deployed web shells, and attempt to remediate the detected compromises. "This new tool is designed as an interim mitigation for customers who are unfamiliar with the patch/update process or who have not yet applied the on-premises Exchange security update," Microsoft  said . The development comes in the wake of indiscriminate attacks against unpatched Exchange Servers across the world by more than ten advanced persistent threat actors — most of the government-backed cyberespionage groups — to plant backdoors, coin miners, and  ransomware ,
Hackers Are Targeting Microsoft Exchange Servers With Ransomware

Hackers Are Targeting Microsoft Exchange Servers With Ransomware

March 12, 2021Ravie Lakshmanan
It didn't take long. Intelligence agencies and cybersecurity researchers had been warning that unpatched Exchange Servers could open the pathway for ransomware infections in the wake of swift escalation of the attacks since last week. Now it appears that threat actors have caught up.  According to the latest reports , cybercriminals are leveraging the heavily exploited ProxyLogon Exchange Server flaws to install a new strain of ransomware called "DearCry." "Microsoft observed a new family of human operated ransomware attack customers – detected as Ransom:Win32/DoejoCrypt.A," Microsoft researcher Phillip Misner  tweeted . "Human operated ransomware attacks are utilizing the Microsoft Exchange vulnerabilities to exploit customers." Microsoft's security intelligence team, in a separate tweet,  confirmed  that it has begun "blocking a new family of ransomware being used after an initial compromise of unpatched on-premises Exchange Servers.&q
ProxyLogon PoC Exploit Released; Likely to Fuel More Disruptive Cyber Attacks

ProxyLogon PoC Exploit Released; Likely to Fuel More Disruptive Cyber Attacks

March 11, 2021Ravie Lakshmanan
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) and the Federal Bureau of Investigation (FBI) on Wednesday issued a joint advisory warning of active exploitation of vulnerabilities in Microsoft Exchange on-premises products by nation-state actors and cybercriminals. "CISA and FBI assess that adversaries could exploit these vulnerabilities to compromise networks, steal information, encrypt data for ransom, or even execute a destructive attack," the agencies  said . "Adversaries may also sell access to compromised networks on the dark web." The attacks have primarily targeted local governments, academic institutions, non-governmental organizations, and business entities in various industry sectors, including agriculture, biotechnology, aerospace, defense, legal services, power utilities, and pharmaceutical, which the agencies say are in line with previous activity conducted by Chinese cyber actors. Tens of thousands of entities, including the  Eur
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