Query: explain T1203 Exploitation for Client Execution
Matching passage: T1203 Exploitation for Client Execution. Tactics: execution. Description: Adversaries may exploit software vulnerabilities in client applications to execute code. Vulnerabilities can exist in software due to unsecure coding practices that can lead to unanticipated behavior. Adversaries can take advantage of certain vulnerabilities through targeted exploitation for the purpose of arbitrary code execution. Oftentimes the most valuable exploits to an offensive toolkit are those that can be used to obtain code execution on a remote system because they can be used to gain access to that system. Users will expect to see files related to the applications they commonly used to do work, so they are a useful target for exploit research and development because of their high utility. Several types exist: ### Browser-based Exploitation Web browsers are a common target through [Drive-by Compromise](https://attack.mitre.org/techniques/T1189) and [Spearphishing Link](https://attack.mitre.org/techniques/T1566/002). Endpoint systems may be compromised through normal web browsing or from certain users being targeted by links in spearphishing emails to adversary controlled sites used to exploit the web browser. These often do not require an action by the user for the exploit to be executed. ### Office Applications Common office and productivity applications such as Microsoft Office are also targeted through [Phishing](https://attack.mitre.org/techniques/T1566). Malicious files will be transmitted directly as attachments or through links to download them. These require the user to open the document or file for the exploit to run. ### Common Third-party Applications Other applications that are commonly seen or are part of the software deployed in a target network may also be used for exploitation. Applications such as Adobe Reader and Flash, which are common in enterprise environments, have been routinely targeted by adversaries attempting to gain access to systems. Depending on the software and nature of the vulnerability, some may be exploited in the browser
Near-miss passage: T1204 User Execution. Tactics: execution. Description: An adversary may rely upon specific actions by a user in order to gain execution. Users may be subjected to social engineering to get them to execute malicious code by, for example, opening a malicious document file or link. These user actions will typically be observed as follow-on behavior from forms of [Phishing](https://attack.mitre.org/techniques/T1566). While [User Execution](https://attack.mitre.org/techniques/T1204) frequently occurs shortly after Initial Access it may occur at other phases of an intrusion, such as when an adversary places a file in a shared directory or on a user's desktop hoping that a user will click on it. This activity may also be seen shortly after [Internal Spearphishing](https://attack.mitre.org/techniques/T1534). Adversaries may also deceive users into performing actions such as: * Enabling [Remote Access Tools](https://attack.mitre.org/techniques/T1219), allowing direct control of the system to the adversary * Running malicious JavaScript in their browser, allowing adversaries to [Steal Web Session Cookie](https://attack.mitre.org/techniques/T1539)s(Citation: Talos Roblox Scam 2023)(Citation: Krebs Discord Bookmarks 2023) * Downloading and executing malware for [User Execution](https://attack.mitre.org/techniques/T1204) * Coerceing users to copy, paste, and execute malicious code manually(Citation: Reliaquest-execution)(Citation: proofpoint-selfpwn) For example, tech support scams can be facilitated through [Phishing](https://attack.mitre.org/techniques/T1566), vishing, or various forms of user interaction. Adversaries can use a combination of these methods, such as spoofing and promoting toll-free numbers or call centers that are used to direct victims to malicious websites, to deliver and execute payloads containing malware or [Remote Access Tools](https://attack.mitre.org/techniques/T1219).(Citation: Telephone Attack Delivery)