Query: Encoded PowerShell / command-line abuse matching Account Access Removal
Matching passage: T1531 Account Access Removal. Tactics: impact. Description: Adversaries may interrupt availability of system and network resources by inhibiting access to accounts utilized by legitimate users. Accounts may be deleted, locked, or manipulated (ex: changed credentials, revoked permissions for SaaS platforms such as Sharepoint) to remove access to accounts.(Citation: Obsidian Security SaaS Ransomware June 2023) Adversaries may also subsequently log off and/or perform a [System Shutdown/Reboot](https://attack.mitre.org/techniques/T1529) to set malicious changes into place.(Citation: CarbonBlack LockerGoga 2019)(Citation: Unit42 LockerGoga 2019) In Windows, [Net](https://attack.mitre.org/software/S0039) utility, <code>Set-LocalUser</code> and <code>Set-ADAccountPassword</code> [PowerShell](https://attack.mitre.org/techniques/T1059/001) cmdlets may be used by adversaries to modify user accounts. Accounts could also be disabled by Group Policy. In Linux, the <code>passwd</code> utility may be used to change passwords. On ESXi servers, accounts can be removed or modified via esxcli (`system account set`, `system account remove`). Adversaries who use ransomware or similar attacks may first perform this and other Impact behaviors, such as [Data Destruction](https://attack.mitre.org/techniques/T1485) and [Defacement](https://attack.mitre.org/techniques/T1491), in order to impede incident response/recovery before completing the [Data Encrypted for Impact](https://attack.mitre.org/techniques/T1486) objective.
Near-miss passage: T1499.002 Service Exhaustion Flood. Tactics: impact. Description: Adversaries may target the different network services provided by systems to conduct a denial of service (DoS). Adversaries often target the availability of DNS and web services, however others have been targeted as well.(Citation: Arbor AnnualDoSreport Jan 2018) Web server software can be attacked through a variety of means, some of which apply generally while others are specific to the software being used to provide the service. One example of this type of attack is known as a simple HTTP flood, where an adversary sends a large number of HTTP requests to a web server to overwhelm it and/or an application that runs on top of it. This flood relies on raw volume to accomplish the objective, exhausting any of the various resources required by the victim software to provide the service.(Citation: Cloudflare HTTPflood) Another variation, known as a SSL renegotiation attack, takes advantage of a protocol feature in SSL/TLS. The SSL/TLS protocol suite includes mechanisms for the client and server to agree on an encryption algorithm to use for subsequent secure connections. If SSL renegotiation is enabled, a request can be made for renegotiation of the crypto algorithm. In a renegotiation attack, the adversary establishes a SSL/TLS connection and then proceeds to make a series of renegotiation requests. Because the cryptographic renegotiation has a meaningful cost in computation cycles, this can cause an impact to the availability of the service when done in volume.(Citation: Arbor SSLDoS April 2012)