Query: explain T1546.008 Accessibility Features
Matching passage: T1546.008 Accessibility Features. Tactics: privilege escalation, persistence. Description: Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system. Two common accessibility programs are <code>C:\Windows\System32\sethc.exe</code>, launched when the shift key is pressed five times and <code>C:\Windows\System32\utilman.exe</code>, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as "sticky keys", and has been used by adversaries for unauthenticated access through a remote desktop login screen. (Citation: FireEye Hikit Rootkit) Depending on the version of Windows, an adversary may take advantage of these features in different ways. Common methods used by adversaries include replacing accessibility feature binaries or pointers/references to these binaries in the Registry. In newer versions of Windows, the replaced binary needs to be digitally signed for x64 systems, the binary must reside in <code>%systemdir%\</code>, and it must be protected by Windows File or Resource Protection (WFP/WRP). (Citation: DEFCON2016 Sticky Keys) The [Image File Execution Options Injection](https://attack.mitre.org/techniques/T1546/012) debugger method was likely discovered as a potential workaround because it does not require the corresponding accessibility feature binary to be replaced. For simple binary replacement on Windows XP and later as well as and Windows Server 2003/R2 and later, for example, the program (e.g., <code>C:\Windows\System32\utilman.exe</code>) may be replaced with "cmd.exe" (or another program that provides backdoor access). Subsequently, pressing the appropriate key combination at the login screen while sitting at the keyboard or when connected
Near-miss passage: T1546.004 Unix Shell Configuration Modification. Tactics: privilege escalation, persistence. Description: Adversaries may establish persistence through executing malicious commands triggered by a user’s shell. User [Unix Shell](https://attack.mitre.org/techniques/T1059/004)s execute several configuration scripts at different points throughout the session based on events. For example, when a user opens a command-line interface or remotely logs in (such as via SSH) a login shell is initiated. The login shell executes scripts from the system (<code>/etc</code>) and the user’s home directory (<code>~/</code>) to configure the environment. All login shells on a system use /etc/profile when initiated. These configuration scripts run at the permission level of their directory and are often used to set environment variables, create aliases, and customize the user’s environment. When the shell exits or terminates, additional shell scripts are executed to ensure the shell exits appropriately. Adversaries may attempt to establish persistence by inserting commands into scripts automatically executed by shells. Using bash as an example, the default shell for most GNU/Linux systems, adversaries may add commands that launch malicious binaries into the <code>/etc/profile</code> and <code>/etc/profile.d</code> files.(Citation: intezer-kaiji-malware)(Citation: bencane blog bashrc) These files typically require root permissions to modify and are executed each time any shell on a system launches. For user level permissions, adversaries can insert malicious commands into <code>~/.bash_profile</code>, <code>~/.bash_login</code>, or <code>~/.profile</code> which are sourced when a user opens a command-line interface or connects remotely.(Citation: anomali-rocke-tactics)(Citation: Linux manual bash invocation) Since the system only executes the first existing file in the listed order, adversaries have used <code>~/.bash_profile</code> to ensure execution. Adversaries have also leveraged the <code>~/.bashrc</code> file which is additionally executed if the connection is established remotely or