Hackers compromised the Microsoft Exchange servers at EBA
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-26855 | Unauthenticated SSRF/RCE in Microsoft Exchange Server (ProxyLogon) CVE-2021-26855 is a server-side request forgery flaw (CWE-918) in Microsoft Exchange Server that allows an unauthenticated remote attacker to send specially crafted HTTP requests and have the Exchange server process them as itself, disclosing sensitive session information. When chained with sibling Exchange flaws (the 'ProxyLogon' chain), it yields authentication bypass and arbitrary file write, escalating to full remote code execution with SYSTEM-level privileges on the on-premises Exchange server. Any organization running an affected on-premises Exchange server reachable over HTTP/HTTPS (typically outbound webmail) is exposed; Exchange Online was not affected. Exploitation is confirmed in the wild at large scale: the flaw was mass-exploited beginning in early 2021 (notably by the HAFNIUM group), is on the CISA KEV with documented ransomware use, and has a maximum EPSS score of 100% (100th percentile), despite no public PoC listing. Do: Apply the vendor's March 2021 Exchange security updates (or later cumulative updates) immediately, per the CISA required action; until patched, limit Exchange (ECP/OWA) exposure to the internet via firewall/VPN rules. Hunt for compromise: review IIS logs for unrecognized authenticated activity against FrontEnd HttpProxy endpoints, and check for malicious files or webshells under inetpub\wwwroot\aspnet_client, given the known ransomware use. | 9.1 group max | 100% | KEV ransomware PoC ×4 |
| masshundreds of thousands of on-premises deployments; tens of thousands of internet-exposed Exchange servers |
Full article339 words · extracted from securityaffairs.com · click to collapse
The European Banking Authority (EBA) disclosed a cyberattack that resulted in the hack of its Microsoft Exchange email system.
The European Banking Authority announced that it was the victim of a cyber attack against its email system that exploited recently disclosed zero-day vulnerabilities in Microsoft Exchange.
On March 2nd, Microsoft has released emergency out-of-band security updates that address four zero-day issues (CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065) in all supported Microsoft Exchange versions that are actively exploited in the wild.
The IT giant reported that at least one China-linked APT group, tracked as HAFNIUM, chained these vulnerabilities to access on-premises Exchange servers to access email accounts, and install backdoors to maintain access to victim environments. According to Microsoft, the Hafnium APT exploited these vulnerabilities in targeted attacks against US organizations.
The US Cybersecurity and Infrastructure Security Agency (CISA) has issued the Emergency Directive 21-02 in response to the disclosure of zero-day vulnerabilities in Microsoft Exchange. The US CISA ordered federal agencies to urgently update or disconnect MS Exchange on-premises installs.
On Sunday, the EU financial regulator disclosed the attack and took offline its email systems in response to the attack as a precautionary measure.
“The European Banking Authority (EBA) has been the subject of a cyber-attack against its Microsoft Exchange Servers, which is affecting many organisations worldwide.” reads a statement published by the EBA. “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 financial agency has launched an investigation into the incident and notified the relevant authorities, EBA is currently working with a team of forensic experts.
According to the EBA, personal data through emails that were maintained on that compromised the email systems may have been obtained by the attacker.
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Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/115396/data-breach/eba-microsoft-exchange-hacked.html