CVE-2024-45433

Executive Summary

CVE-2024-45433 is a critical vulnerability in the OpenSynergy BlueSDK (Blue SDK) Bluetooth stack, affecting versions through 6.x. The flaw is classified as an Incorrect Control Flow Scoping issue (CWE-783), where the software fails to properly manage control flow after detecting an unusual condition. This allows an attacker to bypass security validations and force the processing of malicious incoming data. The vulnerability resides in the core Bluetooth stack logic, making it exploitable over-the-air without physical access. No public proof-of-concept (PoC) or patch details are currently available, but the risk is elevated due to the widespread use of BlueSDK in automotive and IoT embedded systems.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Uncalculated – likely due to incomplete vector data)
• 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): High
• Availability (A): High
• Threat Level: Critical (estimated based on impact and exploitability)

Deep Dive & Mechanics

The vulnerability stems from improper control flow scoping in the BlueSDK Bluetooth stack. When the stack encounters an unusual condition (e.g., malformed L2CAP or SDP packets), it fails to correctly redirect execution to error-handling routines. Instead, the flawed logic allows the incoming data to continue processing, bypassing security checks. This can lead to:

• Buffer overflows due to unchecked data lengths.
• Logic bypasses enabling unauthorized pairing or service discovery.
• Remote code execution if the attacker can craft packets that trigger stack corruption.

The attack surface is broad: any device using BlueSDK (e.g., infotainment systems, telematics units, IoT sensors) within Bluetooth range is vulnerable. The lack of proper return control flow after detecting an anomaly is the root cause, making this a classic "fail-open" security flaw.

Vulnerable vs. Patched Code

No official patch has been released. However, based on the CWE description, the vulnerable code pattern likely resembles:

// Vulnerable pattern: missing return after error detection
void process_packet(uint8_t *data, uint16_t len) {
    if (len > MAX_PACKET_SIZE) {
        // Log error but continue processing
        log_error("Packet too large");
        // Missing return or goto error_handler
    }
    // Process data without validation
    memcpy(buffer, data, len);
}

A patched version would enforce strict control flow:

// Patched pattern: proper error handling
void process_packet(uint8_t *data, uint16_t len) {
    if (len > MAX_PACKET_SIZE) {
        log_error("Packet too large");
        return; // Exit immediately
    }
    // Only process if validation passed
    memcpy(buffer, data, len);
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

1. Environment Setup:

   • Use a Bluetooth-enabled Linux machine with bluez and scapy installed.
   • Target device: Any system running BlueSDK 6.x (e.g., automotive head unit).

2. Crafting Malformed Packets:

   • Send oversized L2CAP connection requests or malformed SDP service records.
   • Example using Scapy:

     from scapy.all import *
     # Craft a malformed L2CAP packet with invalid length
     pkt = BluetoothL2CAP_Hdr() / Raw(b'A'*0xFFFF)
     sendp(pkt, iface="hci0")
     

3. Exploitation Goal:

   • Trigger the control flow bypass to execute arbitrary code or extract sensitive data.

Blue Team (Defense & Detection)

1. Monitor Bluetooth traffic for anomalous packet sizes or malformed headers.
2. Implement network segmentation for Bluetooth-enabled devices.
3. Use host-based intrusion detection to flag unexpected process crashes or memory corruption.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Bluetooth packets with L2CAP length fields exceeding 65535 bytes.
  • Repeated SDP service discovery requests with malformed attributes.
• Host IOCs:
  • Unexpected crashes in blued or BlueSDK processes.
  • Log entries containing "unusual condition" or "error_handler bypass".
• File IOCs:
  • Modified BlueSDK binaries or configuration files.

Detection Engineering

YARA Rule

rule CVE_2024_45433_BlueSDK_ControlFlow {
    meta:
        description = "Detects vulnerable BlueSDK binaries with incorrect control flow scoping"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-45433"
    strings:
        $s1 = "process_packet" ascii wide
        $s2 = "log_error" ascii wide
        $s3 = "memcpy" ascii wide
        $s4 = "MAX_PACKET_SIZE" ascii wide
    condition:
        all of ($s1, $s2, $s3, $s4) and #s1 > 0
}

Sigma Rule

title: CVE-2024-45433 - BlueSDK Control Flow Bypass
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects exploitation attempts against BlueSDK incorrect control flow scoping
author: Valters IT
logsource:
    product: linux
    service: syslog
detection:
    selection:
        - "BlueSDK: unusual condition detected"
        - "BlueSDK: error_handler bypass"
        - "BlueSDK: packet processing without validation"
    condition: selection
falsepositives:
    - Legitimate firmware updates
level: high

Suricata Rule

alert bluetooth any any -> any any (msg:"CVE-2024-45433 - BlueSDK Malformed L2CAP Packet"; content:"|00 00|"; offset:0; depth:2; content:"|FF FF|"; within:4; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate Actions:
  • Disable Bluetooth on affected devices if not required.
  • Apply network-level filtering to block malformed Bluetooth packets.
• Long-term Fix:
  • Await an official patch from OpenSynergy.
  • Implement input validation and strict control flow in custom Bluetooth stacks.
• Workarounds:
  • Use Bluetooth LE (Low Energy) with additional security layers.
  • Monitor for anomalous Bluetooth activity using the provided detection rules.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert