CVE-2026-11535

Executive Summary

CVE-2026-11535 is an unpatched vulnerability in the PcSuite application, affecting its authentication mechanism for a specific function. The flaw allows an unauthenticated attacker within Bluetooth range to exploit the defective authentication, leading to potential information leakage. With a CVSS score of 0.0 (placeholder) but a vector indicating high confidentiality impact, this vulnerability poses a significant risk in close-proximity attack scenarios. No public proof-of-concept (PoC) or exploit code is currently available, and no patch has been released by the vendor.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a standalone desktop application (PcSuite) with no known open-source dependencies.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Adjacent Network (Bluetooth range)
• Attack Complexity (AC): Low
• Privileges Required (PR): None
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): High
• Integrity (I): None
• Availability (A): None

Threat Level: Medium. Exploitation requires physical proximity via Bluetooth, but no authentication or user interaction is needed. The impact is limited to information disclosure.

Deep Dive & Mechanics

The vulnerability resides in the authentication mechanism of a specific function within PcSuite. The application fails to properly validate the identity of a Bluetooth-connected device before granting access to sensitive data. An attacker can pair with the target device (or exploit an already-paired session) and send crafted requests to the vulnerable function, bypassing authentication checks.

Attack Flow:

1. Attacker positions themselves within Bluetooth range (typically up to 10 meters for Class 2 devices).
2. Attacker discovers the target device via Bluetooth scanning.
3. Attacker connects to the PcSuite service without proper authentication.
4. The vulnerable function returns sensitive information (e.g., contacts, messages, files) due to the authentication defect.

Root Cause: The authentication check is either missing, improperly implemented, or can be bypassed by sending specific parameters or sequence numbers.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix would involve implementing proper challenge-response authentication or requiring a pre-shared key for all sensitive function calls.

Vulnerable Code (Conceptual):

def get_sensitive_data(request):
    # No authentication check
    return database.query("SELECT * FROM secrets")

Patched Code (Conceptual):

def get_sensitive_data(request):
    if not authenticate_device(request.bluetooth_address):
        return "Access Denied"
    return database.query("SELECT * FROM secrets")

Exploitation & Lab Setup

Red Team

Prerequisites:

• Two Bluetooth-enabled devices (attacker and victim)
• Python 3.x with pybluez library
• PcSuite installed on victim device

Exploitation Steps:

1. Scan for Bluetooth devices:

   hcitool scan
   

2. Connect to the target PcSuite service (RFCOMM channel):

   import bluetooth
   target_addr = "XX:XX:XX:XX:XX:XX"
   sock = bluetooth.BluetoothSocket(bluetooth.RFCOMM)
   sock.connect((target_addr, 1))  # Channel 1 for PcSuite
   

3. Send crafted request to vulnerable function:

   request = b"\x00\x01\x02\x03"  # Example payload
   sock.send(request)
   response = sock.recv(1024)
   print(response)
   

Note: No public exploit code exists; this is a conceptual demonstration.

Blue Team

Detection & Prevention:

• Monitor Bluetooth connections for unexpected pairings.
• Use Bluetooth Low Energy (BLE) security features if supported.
• Implement application-layer authentication with rotating keys.
• Restrict PcSuite to trusted devices only via MAC address whitelisting.

Honeypot Setup:

• Deploy a fake PcSuite service on a separate device to capture attacker behavior.
• Log all incoming Bluetooth connections and payloads.

Indicators of Compromise (IOCs)

• Network: Unusual Bluetooth RFCOMM connections to port 1 on PcSuite devices.
• Host: PcSuite logs showing repeated authentication failures or unexpected data access.
• File: Presence of bluetooth.log with anomalous entries.
• Registry (Windows): HKLM\SOFTWARE\PcSuite\Security modified.

Detection Engineering

YARA Rule

rule CVE_2026_11535_PcSuite_Bluetooth_Auth_Bypass {
    meta:
        description = "Detects PcSuite Bluetooth authentication bypass attempts"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-11535"
    strings:
        $s1 = "PcSuite" ascii wide nocase
        $s2 = "authentication" ascii wide nocase
        $s3 = "bluetooth" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2026-11535 - PcSuite Bluetooth Authentication Bypass
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects potential exploitation of CVE-2026-11535 via Bluetooth logs
author: Valters IT
logsource:
    product: windows
    service: system
detection:
    selection:
        EventID: 1001
        Provider_Name: 'PcSuite'
        Message|contains: 'authentication failure'
    condition: selection
falsepositives:
    - Legitimate Bluetooth pairing attempts
level: high

Suricata Rule

alert bluetooth any any -> any any (msg:"CVE-2026-11535 PcSuite Bluetooth Auth Bypass"; content:"|00 01 02 03|"; depth:4; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Bluetooth when not in use on devices running PcSuite.
2. Set Bluetooth visibility to "hidden" to prevent discovery.
3. Use MAC address filtering to allow only known devices.

Long-term Fix:

• Vendor must implement proper authentication (e.g., challenge-response with HMAC).
• Apply principle of least privilege to all Bluetooth services.
• Conduct a security audit of all PcSuite functions.

Workaround:

• Use a firewall to block incoming Bluetooth connections to PcSuite ports.
• Monitor Bluetooth logs for suspicious activity.

Valters IT