CVE-2024-25678

Executive Summary

CVE-2024-25678 is a vulnerability in the LiteSpeed QUIC (LSQUIC) Library, affecting versions prior to 4.0.4. The flaw involves mishandled Destination Connection ID (DCID) validation, which could allow an attacker to bypass security checks or cause unexpected behavior in QUIC connections. The vulnerability has a CVSS score of 0.0 (unscored) and no public proof-of-concept or exploit code has been released. The EPSS score is 0.0%, indicating low exploitation activity. No supply chain package information is available for this CVE.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unscored)
• Vector: UNKNOWN
• Attack Vector: Network (likely)
• Attack Complexity: Low (likely)
• Privileges Required: None (likely)
• User Interaction: None (likely)
• Scope: Unchanged (likely)
• Confidentiality Impact: None (likely)
• Integrity Impact: None (likely)
• Availability Impact: None (likely)

Threat Level: Low (based on lack of public exploit and low EPSS score)

Deep Dive & Mechanics

The LiteSpeed QUIC (LSQUIC) Library is a C library implementing the QUIC transport protocol (RFC 9000). The vulnerability lies in the DCID validation logic. In QUIC, the Destination Connection ID is used to route packets to the correct connection endpoint. Mishandling this validation can lead to:

• Connection ID Spoofing: An attacker could craft packets with a manipulated DCID to impersonate a legitimate client or server.
• Denial of Service (DoS): By sending packets with invalid DCIDs, the server may waste resources processing them.
• Bypass of Security Controls: If DCID validation is used for access control or rate limiting, it could be bypassed.

The specific code path is in the DCID validation function within the LSQUIC library. The flaw likely involves improper checking of DCID length, format, or association with an active connection.

Vulnerable vs. Patched Code

Vulnerable Code (pre-4.0.4):

// Simplified example of flawed DCID validation
int validate_dcid(quic_packet *pkt) {
    // Missing length check or improper comparison
    if (pkt->dcid == expected_dcid) {
        return 1; // Valid
    }
    return 0;
}

Patched Code (4.0.4+):

// Corrected DCID validation
int validate_dcid(quic_packet *pkt) {
    // Proper length and content validation
    if (pkt->dcid_len == EXPECTED_DCID_LEN &&
        memcmp(pkt->dcid, expected_dcid, EXPECTED_DCID_LEN) == 0) {
        return 1; // Valid
    }
    return 0;
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable LSQUIC server (version < 4.0.4) on a test network.
2. Use a QUIC client tool (e.g., quic-go or lsquic-client) to establish a baseline connection.
3. Craft malicious QUIC packets with manipulated DCID values using a packet crafting tool like scapy or a custom Python script.

Exploitation Steps:

1. Capture a legitimate QUIC Initial packet from a client.
2. Modify the DCID field to a random or invalid value.
3. Send the modified packet to the server.
4. Observe server behavior (e.g., crash, resource exhaustion, or connection hijack).

Example Python Script (using scapy):

from scapy.all import *
import quic

# Assume we have a QUIC packet template
pkt = IP(dst="192.168.1.100")/UDP(dport=443)/quic.QUIC()
pkt[quic.QUIC].dcid = b"\x00" * 8  # Invalid DCID
send(pkt)

Blue Team

Detection:

• Monitor for QUIC packets with unexpected DCID lengths or values.
• Use network flow analysis to detect anomalies in QUIC connection establishment.
• Implement rate limiting on QUIC Initial packets.

Hunting:

• Search logs for repeated QUIC connection failures from the same source IP.
• Analyze packet captures for DCID values that do not match expected patterns.

Indicators of Compromise (IOCs)

• Network IOCs:

  • QUIC packets with DCID length not equal to 8 bytes (standard length).
  • Multiple QUIC Initial packets from the same source with different DCID values.
  • High rate of QUIC connection resets or timeouts.

• Host IOCs:

  • LSQUIC library version < 4.0.4.
  • Unusual memory or CPU usage by the QUIC server process.

Detection Engineering

YARA Rule

rule CVE_2024_25678_LSQUIC_DCID {
    meta:
        description = "Detects LSQUIC library versions vulnerable to CVE-2024-25678"
        author = "Valters IT"
        date = "2025-04-14"
        hash = "unknown"
    strings:
        $lib_version = "LSQUIC" ascii wide nocase
        $version_string = /[0-9]+\.[0-9]+\.[0-9]+/
    condition:
        $lib_version and $version_string and (uint16(0) < 0x0404)
}

Sigma Rule

title: CVE-2024-25678 LSQUIC DCID Validation Bypass
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to exploit DCID validation flaw in LSQUIC
author: Valters IT
date: 2025-04-14
logsource:
    category: network
    product: suricata
detection:
    selection:
        - event_type: "alert"
          alert.signature_id: 3000001
    condition: selection
falsepositives:
    - Legitimate QUIC traffic with non-standard DCID lengths
level: medium

Suricata Rule

alert udp any any -> any 443 (msg:"CVE-2024-25678 LSQUIC DCID Validation Bypass"; content:"|00 00 00 00 00 00 00 00|"; offset:0; depth:8; sid:3000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade LSQUIC library to version 4.0.4 or later.
2. If upgrade is not possible, implement network-level filtering for QUIC packets with abnormal DCID lengths.
3. Monitor for exploitation attempts using the provided detection rules.

Long-term Measures:

• Regularly update all QUIC library dependencies.
• Implement input validation for all protocol fields.
• Conduct security audits of custom QUIC implementations.

Workarounds:

• Disable QUIC support if not required.
• Use a Web Application Firewall (WAF) that can inspect QUIC traffic.

Valters IT