Microsoft Exchange Server | Breaking Cybersecurity News | The Hacker News

Nicknamed ProxyNotShell, a new exploit used in the wild takes advantage of the recently published Microsoft Server-Side Request Forgery (SSRF) vulnerability CVE-2022-41040 and a second vulnerability, CVE-2022-41082 that allows Remote Code Execution (RCE) when PowerShell is available to unidentified attackers. Based on ProxyShell, this new zero-day abuse risk leverage a chained attack similar to the one used in the 2021 ProxyShell attack that exploited the combination of multiple vulnerabilities - CVE-2021-34523, CVE-2021-34473, and CVE-2021-31207 – to permit a remote actor to execute arbitrary code. Despite the potential severity of attacks using them, ProxyShell vulnerabilities are still on CISA's list of top 2021 routinely exploited vulnerabilities. Meet ProxyNotShell  Recorded on September 19, 2022, CVE-2022-41082 is an attack vector targeting Microsoft's Exchange Servers, enabling attacks of low complexity with low privileges required. Impacted services, if vulnerable, ena...

Security researchers are warning of previously undisclosed flaws in fully patched Microsoft Exchange servers being exploited by malicious actors in real-world attacks to achieve remote code execution on affected systems. The advisory comes from Vietnamese cybersecurity company GTSC, which discovered the shortcomings as part of its security monitoring and incident response efforts in August 2022. The two vulnerabilities, which are formally yet to be assigned CVE identifiers, are being  tracked  by the Zero Day Initiative as  ZDI-CAN-18333  (CVSS score: 8.8) and  ZDI-CAN-18802  (CVSS score: 6.3). GTSC said that successful exploitation of the flaws could be abused to gain a foothold in the victim's systems, enabling adversaries to drop web shells and carry out lateral movements across the compromised network. "We detected web shells, mostly obfuscated, being dropped to Exchange servers," the company  noted . "Using the user-agent, we detected that t...

Researchers have detailed a previously undocumented .NET-based post-exploitation framework called IceApple that has been deployed on Microsoft Exchange server instances to facilitate reconnaissance and data exfiltration. "Suspected to be the work of a state-nexus adversary, IceApple remains under active development, with 18 modules observed in use across a number of enterprise environments, as of May 2022," CrowdStrike  said  in a Wednesday report. The cybersecurity firm, which discovered the sophisticated malware in late 2021, noted its presence in multiple victim networks and in geographically distinct locations. Targeted victims span a wide range of sectors, including technology, academic, and government entities. A post-exploitation toolset, as the name implies, is not used to provide initial access, but is rather employed to carry out follow-on attacks after having already compromised the hosts in question. IceApple is notable for the fact that it's an in-memo...

If you invite guest users into your Entra ID tenant, you may be opening yourself up to a surprising risk.  A gap in access control in Microsoft Entra's subscription handling is allowing guest users to create and transfer subscriptions into the tenant they are invited into, while maintaining full ownership of them.  All the guest user needs are the permissions to create subscriptions in their home tenant, and an invitation as a guest user into an external tenant. Once inside, the guest user can create subscriptions in their home tenant, transfer them into the external tenant, and retain full ownership rights. This stealthy privilege escalation tactic allows a guest user to gain a privileged foothold in an environment where they should only have limited access. Many organizations treat guest accounts as low-risk based on their temporary, limited access, but this behavior, which works as designed, opens the door to known attack paths and lateral movement within the resource t...

A Chinese cyberespionage group known for targeting Southeast Asia leveraged flaws in the Microsoft Exchange Server that came to light earlier this March to deploy a previously undocumented variant of a remote access trojan (RAT) on compromised systems. Attributing the intrusions to a threat actor named  PKPLUG  (aka  Mustang Panda  and HoneyMyte), Palo Alto Networks' Unit 42 threat intelligence team said it identified a new version of the modular PlugX malware, called THOR, that was delivered as a post-exploitation tool to one of the breached servers. Dating back to as early as 2008,  PlugX  is a fully-featured second-stage implant with capabilities such as file upload, download, and modification, keystroke logging, webcam control, and access to a remote command shell. "The variant observed [...] is unique in that it contains a change to its core source code: the replacement of its trademark word 'PLUG' to 'THOR,'" Unit 42 researchers Mike Harbison an...