CVE-2024-7825

Executive Summary

CVE-2024-7825 is a type confusion vulnerability in Webroot SecureAnywhere's Web Shield component, specifically within the wrUrl.Dll module. This flaw allows an attacker to misuse the functionality of the software by providing a resource of an incompatible type, leading to undefined behavior and potential security bypasses. The vulnerability affects Windows systems (ARM, 64-bit, and 32-bit) running SecureAnywhere - Web Shield versions prior to 2.1.2.3. While no public proof-of-concept or exploit code is currently available, the nature of type confusion vulnerabilities in security software poses a significant risk of privilege escalation or defense evasion. The vendor has released a patch (version 2.1.2.3), and immediate updating is strongly recommended.

Supply Chain & Package Security

This vulnerability is not related to open-source package ecosystems (NPM, PyPI, Go, Ruby). It affects a proprietary Windows security product from Webroot. The supply chain risk is limited to the integrity of the Webroot update mechanism and the trustworthiness of the vendor's distribution channels.

CVSS Breakdown & Threat Level

The NVD has not assigned a CVSS score or vector for this CVE. Based on the vulnerability type (CWE-843: Type Confusion) and the affected component (a security product's URL handling module), a reasonable threat assessment is as follows:

• Attack Vector (AV): Network (likely exploitable via malicious web content)
• Attack Complexity (AC): High (requires specific conditions or user interaction)
• Privileges Required (PR): None (exploitation may not require prior access)
• User Interaction (UI): Required (user must visit a malicious site or open a crafted file)
• Scope (S): Unchanged (vulnerability is within the security software)
• Confidentiality (C): High (could lead to information disclosure)
• Integrity (I): High (could allow bypass of security controls)
• Availability (A): High (could cause denial of service or crash)

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H Estimated Base Score: 7.5 (High)

Deep Dive & Mechanics

The vulnerability resides in the wrUrl.Dll module, which is responsible for URL parsing and filtering within Webroot SecureAnywhere's Web Shield. Type confusion (CWE-843) occurs when a program allocates or initializes a resource (such as a pointer or object) as one type but later accesses it as a different, incompatible type. In this context, the DLL likely mishandles certain crafted URL inputs, causing it to interpret a data structure incorrectly.

Technical Mechanics:

1. The Web Shield intercepts HTTP/HTTPS traffic and passes URLs to wrUrl.Dll for analysis.
2. The DLL parses the URL and creates an internal representation (e.g., a structure with fields for scheme, host, path, query).
3. Due to a flaw in the parsing logic, a specially crafted URL can cause the DLL to misinterpret the type of one of these fields (e.g., treating a string as a function pointer or an integer as a memory address).
4. This type confusion can lead to:
   • Memory Corruption: Writing data to an unintended location.
   • Logic Bypass: Causing the security filter to incorrectly classify a malicious URL as safe.
   • Code Execution: In advanced scenarios, an attacker could leverage the confusion to execute arbitrary code within the context of the Web Shield process.

The vulnerability is triggered when a user visits a malicious website or opens a crafted file that causes the Web Shield to process the malformed URL. The lack of public exploit details suggests the specific trigger conditions are not widely known, but the patch (version 2.1.2.3) addresses the root cause by correcting the type handling in the URL parsing routine.

Vulnerable vs. Patched Code

Since the source code for wrUrl.Dll is proprietary, a direct code comparison is not possible. However, based on the vulnerability description, the following conceptual difference is expected:

Vulnerable Code (Conceptual - C/C++):

// Vulnerable: Assumes all parsed URL components are strings
void ParseURL(const char* url) {
    URLComponents comps;
    ParseURLString(url, &comps); // May incorrectly set type flags
    // Type confusion: comps.host might be treated as a function pointer
    if (comps.host_type == STRING) {
        // Safe path
    } else {
        // Unsafe path - type confusion occurs here
        void (*func)() = (void (*)())comps.host;
        func(); // Potential code execution
    }
}

Patched Code (Conceptual):

// Patched: Explicit type checking and safe casting
void ParseURL(const char* url) {
    URLComponents comps;
    if (!ParseURLStringSafe(url, &comps)) {
        // Handle parsing error
        return;
    }
    // Strict type validation before use
    if (comps.host_type == STRING) {
        // Safe string handling
    } else if (comps.host_type == INTEGER) {
        // Safe integer handling
    } else {
        // Reject unknown types
        LogError("Invalid URL component type");
        return;
    }
}

The patch likely introduces rigorous type validation and safe casting mechanisms to prevent the misinterpretation of data structures.

Exploitation & Lab Setup

No public exploit code is available for CVE-2024-7825. The following sections provide a theoretical framework for analysis.

Red Team (Offensive)

Objective: Bypass Webroot Web Shield to deliver malware or exfiltrate data.

Lab Setup:

• Target: Windows 10/11 VM with Webroot SecureAnywhere (vulnerable version < 2.1.2.3) installed and Web Shield enabled.
• Attacker: Kali Linux VM with a web server hosting a crafted URL trigger.
• Tooling: Custom Python script to generate malformed URLs, Burp Suite for traffic manipulation.

Exploitation Steps (Theoretical):

1. Reconnaissance: Identify the vulnerable wrUrl.Dll version (e.g., via process listing or file properties).
2. Craft Payload: Develop a URL that triggers the type confusion. This may involve:
   • Using non-standard characters in the hostname (e.g., null bytes, Unicode overflows).
   • Manipulating the URL scheme to cause a parsing error.
   • Embedding a pointer or function address within the URL string.
3. Delivery: Host the malicious URL on a controlled web server. Send a phishing link to the target user.
4. Trigger: When the user visits the URL, the Web Shield processes it, triggering the type confusion.
5. Post-Exploitation: If code execution is achieved, escalate privileges or disable the security software.

Example Payload (Conceptual):

# Python script to generate a potentially triggering URL
def generate_malicious_url():
    # This is a placeholder - actual trigger is unknown
    payload = "http://" + "\x00" * 100 + ".evil.com/"
    return payload

print(generate_malicious_url())

Blue Team (Defensive)

Objective: Detect and block exploitation attempts.

Detection Strategy:

• Network Monitoring: Look for URLs with anomalous structures (e.g., excessive null bytes, unusual encoding, or non-standard characters in the host field).
• Endpoint Monitoring: Monitor wrUrl.Dll for crashes or unusual memory access patterns. Use Sysmon to log process creation and DLL loads.
• Log Analysis: Review Webroot logs for errors related to URL parsing or module failures.

Hunting Queries:

• Splunk: index=windows sourcetype=WinEventLog:Security EventCode=4688 (CommandLine contains "wrUrl.Dll") OR (Image contains "wrUrl.Dll")
• ELK: winlog.event_id: 4688 AND process.command_line: *wrUrl.Dll*

Indicators of Compromise (IOCs)

• File Hash (SHA-256): (Placeholder - obtain from vendor or analysis)
  • wrUrl.Dll (vulnerable version): e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
  • wrUrl.Dll (patched version 2.1.2.3): a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a
• Network Indicators:
  • URLs containing excessive null bytes or non-printable characters.
  • Outbound connections to domains with unusual TLDs or long subdomains.
• Registry Keys:
  • HKLM\SOFTWARE\WOW6432Node\Webroot\SecureAnywhere\CurrentVersion\Modules\wrUrl (version information)
• Process Indicators:
  • wrUrl.Dll loaded into WRSA.exe or WebrootSecureAnywhere.exe.
  • Unexpected crashes of WRSA.exe or high CPU usage by the Web Shield process.

Detection Engineering

YARA Rule

rule CVE_2024_7825_Webroot_TypeConfusion {
    meta:
        description = "Detects potentially malicious URLs targeting CVE-2024-7825 type confusion in Webroot wrUrl.Dll"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-7825"
        hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    strings:
        $s1 = "wrUrl.Dll" ascii wide nocase
        $s2 = "http://" ascii wide
        $s3 = "https://" ascii wide
        $hex1 = { 00 00 00 00 } // null bytes in URL
        $hex2 = { 25 30 30 } // %00 encoding
    condition:
        (uint16(0) == 0x5A4D or uint32(0) == 0x00004550) and // PE file
        ($s1) and
        (($s2 or $s3) and (#hex1 > 2 or #hex2 > 2))
}

Sigma Rule

title: Potential Exploitation of CVE-2024-7825 - Webroot Type Confusion
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects network traffic or process behavior indicative of exploitation of CVE-2024-7825 in Webroot SecureAnywhere.
author: Valters IT
date: 2024-10-27
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-7825
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\WRSA.exe'
        DestinationPort: 80
        DestinationHostname|contains: 
            - '%00'
            - '\x00'
    condition: selection
falsepositives:
    - Legitimate URLs with encoded null bytes (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-7825 - Webroot Type Confusion Exploit Attempt"; flow:to_server,established; content:"|00|"; http_uri; pcre:"/[\x00]/R"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Patch: Update Webroot SecureAnywhere - Web Shield to version 2.1.2.3 or later. This is the only definitive fix.
2. Verify: Confirm the update by checking the version of wrUrl.Dll in C:\Program Files\Webroot\WRSA.exe or the equivalent installation directory.
3. Monitor: Review Webroot logs for any errors or crashes related to URL parsing.

Long-Term Mitigations:

• Network Segmentation: Limit outbound internet access for critical systems to reduce exposure to malicious URLs.
• Web Filtering: Use a web proxy or DNS filtering to block known malicious domains and URLs with anomalous structures.
• User Training: Educate users on phishing risks and the importance of not clicking suspicious links.
• Defense in Depth: Deploy additional endpoint detection and response (EDR) solutions to monitor for post-exploitation activity.

Workarounds (if patching is delayed):

• Disable the Web Shield component temporarily (not recommended as it reduces security).
• Implement custom firewall rules to block traffic to untrusted external networks.

Valters IT
DevSecOps & Cyber Threat Intelligence