Windows UAC

Windows User Account Control (UAC)

What is UAC?

• Security Layer: UAC is a Windows security feature designed to prevent unauthorized changes to the system.

• Prompts: When a program needs administrative privileges, UAC triggers a prompt, requiring the user to either approve or deny the requested elevation.

• Goal: Limit the potential for malware to silently obtain administrator-level access and make harmful changes.

Types of UAC Attacks

• UAC Bypass: These attacks attempt to execute malicious code with elevated privileges without triggering a UAC prompt. Techniques can include:

  • DLL Hijacking: Exploiting vulnerabilities in how programs load DLL files to inject malicious code.

  • Fileless UAC Bypasses: Using existing, trusted Windows binaries for malicious activities (e.g., through tools like PowerShell).

• UAC Prompt Spoofing/Social Engineering: Aim to trick the user into clicking "Yes" on a fake UAC prompt, authorizing the malware. These attacks often disguise the malicious program as legitimate software updates or installers.

• Consent Fatigue: Repeatedly bombard the user with legitimate UAC prompts with the hope that they'll get tired of them and carelessly approve a malicious request.

Why target UAC?

• Elevated Privileges: Bypassing or subverting UAC allows attackers to gain the administrative power they need to install rootkits, disable security features, steal sensitive data, or cause major system damage.

How to Protect Yourself

• Keep System and Software Updated: Patches fix known vulnerabilities attackers exploit for UAC bypasses.

• Run as Standard User: Avoid using an admin account for everyday tasks to limit the damage if malware successfully gets elevated privileges.

• Scrutinize UAC Prompts: Pay close attention to the publisher and what the program is requesting. Don't blindly approve prompts.

• Consider a Security Solution: Antivirus and anti-malware software can offer additional layers of protection and may detect malicious behavior.

Examples of UAC Attacks (Simplified)

• DLL Hijacking Example: An attacker places a malicious DLL with the same name as a legitimate DLL in a directory a program is likely to search. When the program executes, UAC bypass occurs if it loads the malicious DLL, allowing the attacker's code to run with elevated privileges.

• Social Engineering Example: Malware displays a fake UAC prompt resembling a system update. An unsuspecting user who clicks "Yes" unwittingly grants administrative privileges to the malware.

Important Notes

• UAC is not a foolproof security mechanism and can be bypassed.

• User vigilance is a crucial defense against these kinds of attacks.