CVE-2025-1253

Executive Summary

CVE-2025-1253 is a critical stack-based buffer overflow vulnerability in RTI Connext Professional Core Libraries. The flaw allows an attacker to overflow variables and tags by sending a specially crafted buffer without proper size checking. This can lead to remote code execution, denial of service, or data corruption. The vulnerability affects multiple version branches of Connext Professional, spanning from 4.5c to 7.4.0. No public proof-of-concept or patch details are currently available, but the risk is elevated due to the widespread use of RTI Connext in industrial, medical, and defense systems.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary C/C++ middleware library (RTI Connext Professional) used in embedded and real-time systems. Organizations should verify their software bill of materials (SBOM) for any RTI Connext components and assess exposure.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, likely due to incomplete NVD data. Based on the vulnerability type (stack-based buffer overflow in a network-facing library), the estimated CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N) – likely exploitable over DDS protocol.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): None (N) – no authentication needed.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – affects only the vulnerable component.
• Confidentiality (C): High (H) – memory corruption can leak data.
• Integrity (I): High (H) – arbitrary code execution possible.
• Availability (A): High (H) – crash or denial of service.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical. The vulnerability is remotely exploitable, requires no authentication, and can lead to full system compromise.

Deep Dive & Mechanics

The vulnerability is a classic stack-based buffer overflow (CWE-121) in the Core Libraries of RTI Connext Professional. The DDS (Data Distribution Service) middleware processes incoming data samples and metadata. When parsing variable-length fields or tags, the code copies data into a fixed-size stack buffer without verifying that the input size does not exceed the buffer capacity.

Root Cause: The function responsible for deserializing or processing user-controlled data (e.g., topic names, type definitions, or sample payloads) uses a memcpy or similar operation with a size derived from the network packet, but the destination buffer is allocated on the stack with a fixed size (e.g., 256 bytes). An attacker can send a packet with a size field larger than the buffer, causing a stack overflow.

Impact: Overwriting the saved return address and other stack variables allows an attacker to hijack execution flow. This can lead to arbitrary code execution in the context of the Connext process, which often runs with high privileges in critical infrastructure.

Affected Components: The vulnerability exists in the Core Libraries, which are used by all Connext Professional applications. Any service that listens for DDS data on the network is potentially exploitable.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical example of the vulnerable pattern and a secure fix.

Vulnerable Code (C/C++):

void process_tag(char *input, size_t input_len) {
    char buffer[256];
    // No size check - classic overflow
    memcpy(buffer, input, input_len);
    // ... process buffer
}

Patched Code (Hypothetical):

void process_tag(char *input, size_t input_len) {
    char buffer[256];
    if (input_len > sizeof(buffer) - 1) {
        // Log error and reject
        return;
    }
    memcpy(buffer, input, input_len);
    buffer[input_len] = '\0';
    // ... process buffer
}

The fix adds a bounds check before the copy operation, ensuring the input length does not exceed the buffer capacity.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A target running RTI Connext Professional (any affected version).
• Network access to the DDS discovery or data port (typically UDP 7400-7500 or user-defined).
• Ability to craft raw DDS packets.

Exploitation Steps:

1. Reconnaissance: Scan for RTI Connext services using Shodan or Nmap with a DDS probe.
2. Craft Payload: Create a DDS packet with an oversized tag field. The payload should include shellcode or a ROP chain to execute a reverse shell.
3. Send Exploit: Use a tool like Scapy or a custom C program to send the malicious packet to the target's DDS port.
4. Trigger: The target processes the packet, overflows the stack, and executes the attacker's code.

Example Payload Structure (Python with Scapy):

from scapy.all import *
import struct

# Craft a malformed DDS sample with oversized tag
payload = b"A" * 256  # Fill buffer
payload += struct.pack("<I", 0xdeadbeef)  # Overwrite return address
# ... add ROP chain or shellcode

# Send via UDP
send(IP(dst="target_ip")/UDP(sport=12345, dport=7400)/Raw(load=payload))

Note: No public exploit code is available. The above is a conceptual example.

Blue Team (Defense & Detection)

Detection Strategy:

• Monitor for unusually large DDS packets (e.g., > 1024 bytes for tag fields).
• Enable stack canaries and ASLR on the host OS.
• Use network intrusion detection to flag malformed DDS messages.

Honeypot Setup:

• Deploy a decoy RTI Connext service on a non-production network.
• Log all incoming DDS packets and alert on any that exceed expected field sizes.

Indicators of Compromise (IOCs)

• Network IOCs:
  • UDP packets to/from ports 7400-7500 with payloads exceeding 1024 bytes.
  • DDS discovery packets with malformed or oversized tag fields.
• Host IOCs:
  • Unexpected crashes or segmentation faults in rti_connext processes.
  • Presence of shellcode or abnormal memory regions in the process address space.
  • Unusual outbound connections from the Connext host (e.g., reverse shells).
• File IOCs:
  • Modified binaries or libraries in the RTI installation directory.
  • Unexpected core dump files in /var/crash/ or similar.

Detection Engineering

YARA Rule

rule CVE_2025_1253_RTI_Connext_Overflow {
    meta:
        description = "Detects potential exploitation of CVE-2025-1253 in RTI Connext Professional"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-1253"
    strings:
        $s1 = "RTI Connext" ascii wide nocase
        $s2 = "DDS" ascii wide nocase
        $s3 = { 41 41 41 41 } // Pattern of 'AAAA' overflow
    condition:
        $s1 and $s2 and #s3 > 64
}

Sigma Rule

title: CVE-2025-1253 RTI Connext Stack Overflow Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects network traffic indicative of exploitation of CVE-2025-1253
author: Valters IT
date: 2025-04-10
logsource:
    category: network_connection
    product: suricata
detection:
    selection:
        dest_port: 7400-7500
        ip_protocol: udp
        length: ">1024"
    condition: selection
falsepositives:
    - Legitimate large DDS messages (rare)
level: high

Suricata Rule

alert udp any any -> any 7400-7500 (msg:"CVE-2025-1253 RTI Connext Stack Overflow Attempt"; content:"|41 41 41 41|"; offset:0; depth:256; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: If possible, disconnect RTI Connext services from untrusted networks.
2. Apply network segmentation: Restrict DDS traffic to trusted IP ranges using firewalls.
3. Monitor for exploitation: Deploy the provided detection rules.

Long-Term Fix:

• Vendor Patch: Await an official patch from RTI. Contact RTI support for hotfixes.
• Upgrade: Once available, upgrade to Connext Professional 7.5.0 or later, or apply the specific patch for your version branch.
• Compile with protections: If source code is available, recompile with stack canaries (-fstack-protector-strong) and ASLR.

Workaround:

• Disable dynamic discovery or restrict tag processing if possible via configuration.

Valters IT