The best course of action is to install the Microsoft update on all systems after testing it in a controlled environment. If exploited successfully, an attacker can access a user’s Net-NTLMv2 hash, which can be used to execute a pass-the-hash attack on another service and authenticate as the user. "This can lead to exploitation before the email is even viewed in the Preview Pane. "The attack can be executed without any user interaction by sending a specially crafted email which triggers automatically when retrieved by the email server," Mike Walters, VP of Vulnerability and Threat Research at Action1, said. ![]() "A threat actor is currently exploiting this vulnerability to deliver malicious MSI (Microsoft Installer) files," Bharat Jogi, director of vulnerability and threat research at Qualys, said. ![]() ![]() MORE FROM FORBES Why You Should Stop Using LastPass After New Hack Method Update By Davey Winder "Given the network attack vector, the ubiquity of SMB shares, and the lack of user interaction required, an attacker with a suitable existing foothold on a network may well consider this vulnerability a prime candidate for lateral movement," Adam Barnett, lead software engineer at Rapid7, said. "Microsoft has shared two temporary mitigations if you’re unable to patch immediately, both of which will impact NTLM and applications that use it, so proceed with caution." "Administrators should patch within the day if possible since the vulnerability is relatively simple to exploit, doesn’t require user interaction, and is already being exploited in the wild," Peter Pflaster, a technical product manager at Automox, said. Microsoft mitigations for CVE-2023-23397 Microsoft/Davey Winder What is the security industry saying about the Microsoft Outlook zero-day? Adding users to the Protected Users Security Group will prevent the use of NTLM for authentication, but Microsoft warns that this could "cause impact to applications that require NTLM." Alternatively, you can block outbound TCP 445/SMB using a firewall or through VPN settings. To see the latest version information for click-to-run installations, click Update Options, and then click View Updates. That said, if your organization is unable to apply these security updates immediately, then Microsoft has published some workaround mitigations. If you see Office Updates under Product Information, as shown in the following figure, you are using a click-to-run installation of Office. Applying the relevant patch is therefore recommended. The good news is that the warning concerning CVE-2023-23397 coincides with the release of the latest Patch Tuesday round of security updates for Microsoft users. MORE FROM FORBES Has Amazon's Ring Been Hacked? Ransomware Gang Posts Threat To Leak Data By Davey Winder What do you need to do now? In order to exploit CVE-2023-23397, which Mandiant says is 'trivial' to execute, an attacker needs to send a malicious email with an "extended MAPI property that contains a UNC path to SMB (TCP 445) share on an attacker-controlled server." This kicks off what is known as a 'Pass the Hash' attack, but in this case, is triggered upon receipt of the email by an unpatched Outlook client, without the target even viewing it. Indeed, Mandiant says that it "anticipates broad, rapid adoption of the CVE-2023-23397 exploit by multiple nation-state and financially motivated actors, including both criminal and cyber espionage actors." Pass the Hash attack Given that this is a no-user-interaction exploit, the potential for harm is high. If you already have an SPF record, then you will need to edit it. The race has already begun." Multiple proofs-of-concept now widely availableįurthermore, Mandiant says that multiple proofs-of-concept are now widely available. Content/Value: vspf1 include: -all (or copy paste it from Microsoft 365 ( step 4 )) Click Save. This is an excellent tool for nation-state actors and criminals alike who will be on a bonanza in the short term. "These are spies, and they have a long track record of successfully evading our notice. To download an update, select the corresponding Knowledge Base article in the following list, and then go to the "How to download and install the update" section of the article."This is more evidence that aggressive, disruptive, and destructive cyberattacks may not remain constrained to Ukraine and a reminder that we cannot see everything," John Hultquist, head of Mandiant Intelligence Analysis at Google Cloud, said. Step2 Go to File> Info> Account and Social Network Settings. We recommend that you install all updates that apply to you. To check your Microsoft exchange service connection, follow the below steps: Step1 Open Outlook. ![]() These updates are intended to help our customers keep their computers up-to-date. Microsoft released the following security and nonsecurity updates for Office in March 2023.
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