![]() They achieve this by enabling ‘ Restricted Admin Mode’. In many environments which implement a 3rd party MFA provider, an attacker can remove the MFA restriction with their SMB-based shell. Depending on the environment, SMB may also provide adversaries the ability to disable security controls (including MFA) and improve their position in the network. #DENY LOGON LOCALLY POWERSHELL CODE#SMB can provide a convenient MFA bypass for adversaries, handing them a foothold that will allow for remote code execution without any additional authentication factor. The risk created by SMB is especially important in mature environments where multi-factor authentication is required for administrative access to servers. There’s high probability that they’ll be able to gain code execution on the remote host and expand their attack surface in the environment. Network access to the SMB service (TCP port 139 or 445) and. ![]() Ryan Hausknecht (SpecterOps) published an excellent blog that goes into detail on Offensive Lateral Movement including details about SMB here.įor the purpose of this defensive blog post, we can oversimplify Ryan’s post and say that when an adversary has both: It can also provide an authenticated inter-process communication mechanism between nodes. SMB is well-known for file services and for printers, but it’s much more versatile than that. Why is SMB-based lateral movement effective?Īt a high level, Server Message Block (SMB) is a network communication protocol that can provide shared access to services on a network. This blog post aims to consolidate the defensive information we’ve compiled in our efforts to restrict SMB-based lateral movement, after many iterations against the SpecterOps Adversary Simulation Team. In most organizations, the list will include Domain Controllers (the SYSVOL share), File Servers, and PowerShell logging servers, at the very least. In our engagements with the SpecterOps team, this mechanism is consistently targeted for abuse.Įven in networks where significant efforts have been made to eliminate unnecessary SMB exposure, there are usually a small number of servers with a business-critical need to serve files to legitimate clients. #DENY LOGON LOCALLY POWERSHELL WINDOWS#Lateral movement via Windows Server Message Block (SMB) is consistently one of the most effective techniques used by adversaries. To that end, the Adversary Simulation team at SpecterOps perform regular red team engagements inside the various Palantir networks and leverage their latest tools and techniques to provide a continual feedback loop for defensive security improvement. When Palantir entered into a technical collaboration partnership with SpecterOps in 2018, one of our key initiatives was the advancement of defensive capabilities against the latest Windows security tradecraft. Restricting SMB-based Lateral Movement in a Windows Environment ![]()
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