CVE-2017-16949

What is this vulnerability?

CVE-2017-16949 is categorized as a critical Unrestricted File Upload flaw with a CVSS base score of 9.8. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.

An issue was discovered in the AccessKeys AccessPress Anonymous Post Pro plugin through 3.1.9 for WordPress. Improper input sanitization allows the attacker to override the settings for allowed file extensions and upload file size, related to inc/cores/file-uploader.php and file-uploader/file-uploader-class.php. This allows the attacker to upload anything they want to the server, as demonstrated by an action=ap_file_upload_action&allowedExtensions[]=php request to /wp-admin/admin-ajax.php that results in a .php file upload and resultant PHP code execution.

This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.

Risk Assessment

Impact on Systems

✅ Data Exfiltration: Attackers can extract sensitive data from backend databases, configuration files, or internal services.

✅ Authentication Bypass: Exploiting this flaw may allow unauthorized access to protected resources and administrative interfaces.

✅ Lateral Movement: Once initial access is gained, attackers can pivot to internal systems and escalate privileges.

How to Fix and Mitigate CVE-2017-16949

1. Apply Vendor Patches: Upgrade affected components to their latest, non-vulnerable versions immediately.
2. Implement Input Validation: Ensure all user-supplied data is validated, sanitized, and type-checked before processing.
3. Deploy Runtime Protection: Use Precogs continuous monitoring to detect exploitation attempts in real time.
4. Audit Dependencies: Review and update all third-party libraries and transitive dependencies.

Defending with Precogs AI

Precogs AI Analysis Engine identifies this vulnerability class through semantic code analysis powered by Code Property Graph (CPG) technology, performing inter-procedural taint tracking to detect injection flaws, broken authentication, and insecure data flows across your entire codebase.

Use Precogs to continuously scan your codebase, binaries, APIs, and infrastructure for this vulnerability class and related attack patterns. Our AI-powered detection engine combines static analysis with threat intelligence to identify exploitable weaknesses before attackers do.

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Vulnerability Code Signature

Attack Data Flow

Vulnerable Code Pattern

// ❌ VULNERABLE: Unrestricted Upload
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
// Taint sink: saving file without extension/type validation
move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file);

Secure Code Pattern

// ✅ SECURE: Validated Upload
$target_dir = "uploads/";
$filename = basename($_FILES["fileToUpload"]["name"]);
$filetype = strtolower(pathinfo($filename, PATHINFO_EXTENSION));

// Sanitized validation: strict allowlist
$allowed_types = array("jpg", "png", "gif");
if (in_array($filetype, $allowed_types)) {
    // Generate safe unique filename
    $safe_filename = uniqid() . "." . $filetype;
    move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_dir . $safe_filename);
}

How Precogs Detects This

Precogs AI Analysis Engine utilizes semantic taint tracking to detect insecure file upload routines and missing extension validation.