CVE-2023-7241

Executive Summary

CVE-2023-7241 is a privilege escalation vulnerability in Webroot Antivirus (versions 8.0.1X through 9.0.35.12) affecting both Windows 64-bit and 32-bit systems. The flaw resides in the WRSA.EXE process, which improperly handles file operations, allowing a low-privileged attacker to abuse the process to delete arbitrary and protected files. This can lead to system instability, denial of service, or further exploitation by removing critical system files or security controls. The vulnerability has a CVSS score of 7.9 (High) and is currently unpatched, with no public proof-of-concept or exploit code available. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the risk remains significant for targeted attacks.

CVSS Breakdown & Threat Level

• CVSS Score: 7.9 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Local (AV:L) – requires local access to the system.
• Attack Complexity: Low (AC:L) – no special conditions needed.
• Privileges Required: Low (PR:L) – attacker needs only user-level access.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – potential to read protected files.
• Integrity Impact: High (I:H) – ability to delete or modify protected files.
• Availability Impact: High (A:H) – deletion of critical files can cause system crash.

Threat Level: High. The vulnerability allows a low-privileged attacker to escalate privileges and perform arbitrary file deletions, which can be used to disable security software, corrupt system files, or prepare for further attacks.

Deep Dive & Mechanics

The vulnerability exists in the WRSA.EXE process, which is the core service of Webroot Antivirus. The service runs with high integrity (SYSTEM) privileges to perform file scanning and protection. Due to improper access control or input validation, WRSA.EXE can be tricked into deleting files that it normally protects, including system files or other security-related binaries.

Root Cause: The service likely exposes an inter-process communication (IPC) mechanism (e.g., named pipe, RPC, or shared memory) that allows low-privileged processes to request file operations. The service fails to properly validate the target file path or the caller's permissions, allowing arbitrary file deletion.

Attack Flow:

1. Attacker gains initial access to the system (e.g., via phishing or malware).
2. Attacker identifies the IPC endpoint of WRSA.EXE (e.g., a named pipe like \\.\pipe\WRSA_Control).
3. Attacker sends a crafted request to delete a protected file (e.g., C:\Windows\System32\drivers\etc\hosts or a security product's executable).
4. WRSA.EXE executes the deletion with SYSTEM privileges, bypassing normal file protection mechanisms.

Impact: The attacker can delete critical system files, causing denial of service, or remove security software components to evade detection. This can be used as a precursor to installing malware or ransomware.

Vulnerable vs. Patched Code

Since no patch is available, a comparison is not possible. However, based on the vulnerability description, the following code patterns are likely involved:

Vulnerable Code (Hypothetical):

// WRSA.EXE - Vulnerable file deletion handler
void HandleDeleteRequest(IPCRequest* req) {
    char* path = req->path;
    // No validation of path or caller privileges
    DeleteFile(path);
}

Patched Code (Hypothetical):

// WRSA.EXE - Patched file deletion handler
void HandleDeleteRequest(IPCRequest* req) {
    char* path = req->path;
    // Validate caller has admin privileges
    if (!IsCallerAdmin()) {
        return ACCESS_DENIED;
    }
    // Validate path is within allowed scope
    if (!IsPathAllowed(path)) {
        return ACCESS_DENIED;
    }
    DeleteFile(path);
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Windows 10/11 (64-bit) with Webroot Antivirus 8.0.1X-9.0.35.12 installed.
• Low-privileged user account.

Exploitation Steps:

1. Identify the IPC mechanism (e.g., named pipe \\.\pipe\WRSA_Control).
2. Craft a malicious IPC request to delete a protected file (e.g., C:\Windows\System32\drivers\etc\hosts).
3. Send the request to the pipe.
4. Verify file deletion.

Example Code (Python):

import win32pipe, win32file, pywintypes

def delete_file_via_wrsa(target_path):
    pipe_name = r'\\.\pipe\WRSA_Control'
    try:
        handle = win32file.CreateFile(
            pipe_name,
            win32file.GENERIC_READ | win32file.GENERIC_WRITE,
            0,
            None,
            win32file.OPEN_EXISTING,
            0,
            None
        )
        # Craft request (format unknown, assume simple string)
        request = f"DELETE {target_path}\0"
        win32file.WriteFile(handle, request.encode())
        print(f"Request sent to delete {target_path}")
    except pywintypes.error as e:
        print(f"Error: {e}")

delete_file_via_wrsa(r"C:\Windows\System32\drivers\etc\hosts")

Blue Team

Detection:

• Monitor for unusual IPC connections to WRSA.EXE from non-admin processes.
• Log file deletion events (Event ID 4663) with process name WRSA.EXE and unusual target paths.
• Use Sysmon to track process creation and file deletion.

Hunting:

• Search for WRSA.EXE creating child processes or accessing sensitive paths.
• Look for anomalies in the \\.\pipe\WRSA_Control pipe usage.

Indicators of Compromise (IOCs)

• Process: WRSA.EXE performing file deletions on protected paths (e.g., C:\Windows\System32, C:\Program Files).
• File Paths: Unusual deletion requests to C:\Windows\System32\drivers\etc\hosts, C:\Windows\System32\config\SAM, etc.
• Named Pipe: \\.\pipe\WRSA_Control accessed by non-admin processes.
• Event Logs: Windows Security Event ID 4663 with WRSA.EXE as process and DELETE access.

Detection Engineering

YARA Rule

rule CVE_2023_7241_WRSA_Abuse {
    meta:
        description = "Detects attempts to abuse WRSA.EXE for arbitrary file deletion"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-7241"
    strings:
        $pipe = "WRSA_Control" nocase
        $delete_cmd = "DELETE" nocase
        $sensitive_path1 = "System32" nocase
        $sensitive_path2 = "Program Files" nocase
    condition:
        $pipe and $delete_cmd and ($sensitive_path1 or $sensitive_path2)
}

Sigma Rule

title: CVE-2023-7241 WRSA.EXE Arbitrary File Deletion
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects WRSA.EXE deleting protected files via IPC abuse
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2023-7241
logsource:
    product: windows
    service: security
    category: file_event
detection:
    selection:
        EventID: 4663
        ProcessName|endswith: '\WRSA.EXE'
        AccessMask: '0x6'  # DELETE
    filter:
        ObjectName|startswith:
            - 'C:\ProgramData\Webroot'
            - 'C:\Windows\Temp'
    condition: selection and not filter
falsepositives:
    - Legitimate Webroot updates
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2023-7241 WRSA.EXE IPC Abuse"; content:"WRSA_Control"; content:"DELETE"; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems from the network if possible.
2. Restrict access to the WRSA.EXE process by applying AppLocker or Windows Defender Application Control (WDAC) policies to prevent non-admin processes from interacting with it.
3. Monitor logs for suspicious file deletions by WRSA.EXE.

Long-term Fix:

• Vendor Patch: Await an official patch from Webroot. Contact Webroot support for updates.
• Workaround: If possible, disable the vulnerable IPC feature or restrict its access via firewall rules (e.g., block named pipe access from non-admin users).
• Alternative: Consider replacing Webroot Antivirus with a patched alternative until a fix is available.

Detection Hardening:

• Deploy the provided YARA, Sigma, and Suricata rules.
• Enable advanced auditing for file deletion events (Event ID 4663).

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert