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The Hacker News - Cybersecurity News and Analysis: Microsoft Exchange

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
Microsoft Exchange Hackers Also Breached European Banking Authority

Microsoft Exchange Hackers Also Breached European Banking Authority

March 09, 2021Ravie Lakshmanan
The European Banking Authority (EBA) on Sunday said it had been a victim of a cyberattack targeting its Microsoft Exchange Servers, forcing it to temporarily take its email systems offline as a precautionary measure. "As the vulnerability is related to the EBA's email servers, access to personal data through emails held on that servers may have been obtained by the attacker," the Paris-based regulatory agency  said . EBA said it's launched a full investigation into the incident in partnership with its information and communication technology (ICT) provider, a team of forensic experts, and other relevant entities. In a second update issued on Monday, the agency said it had secured its email infrastructure and that it found no evidence of data extraction, adding it has "no indication to think that the breach has gone beyond our email servers." Besides deploying extra security measures, EBA also noted it's closely monitoring the situation after restor
Microsoft Exchange Cyber Attack — What Do We Know So Far?

Microsoft Exchange Cyber Attack — What Do We Know So Far?

March 08, 2021Ravie Lakshmanan
Microsoft on Friday warned of active attacks exploiting unpatched Exchange Servers carried out by multiple threat actors, as the hacking campaign is believed to have infected tens of thousands of businesses, government entities in the U.S., Asia, and Europe. The company  said  "it continues to see increased use of these vulnerabilities in attacks targeting unpatched systems by multiple malicious actors beyond HAFNIUM," signaling an escalation that the breaches are no longer "limited and targeted" as was previously deemed. According to independent cybersecurity journalist  Brian Krebs , at least 30,000 entities across the U.S. — mainly small businesses, towns, cities, and local governments — have been compromised by an "unusually aggressive" Chinese group that has set its sights on stealing emails from victim organizations by exploiting previously undisclosed flaws in Exchange Server. Victims are also being reported from outside the U.S., with email s
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