vulnerabilities

CVE-2024-39431: Remote Code Exec via Vehicle Modem SoC

breachwire TeamDec 17, 20256 min read

Executive Summary

Security researchers have unveiled a critical vulnerability (CVE-2024-39431) in the modem firmware of Unisoc’s UIS7862A SoC, a chipset widely embedded in the head units of modern Chinese vehicles. Exploiting this flaw enabled remote code execution and full control over the infotainment system—posing a significant risk to road safety, user privacy, and enterprise fleet security.

CISOs managing connected car ecosystems, public-sector agencies, or embedded IoT deployments in transit networks must consider this a high-priority alert. Vulnerabilities discovered in modem-layer firmware—previously seen as a low-threat vector—demonstrate how attackers can pivot across hardware-software boundaries. Miss this in your daily threat intelligence, and you may miss the next nation-state backdoor lurking in your automotive supply chain.

What Happened

Kaspersky ICS CERT researchers analyzed the Unisoc UIS7862A SoC frequently found in modern vehicle head units. Within the 3G protocol stack, they discovered a stack-based buffer overflow in the RLC protocol implementation—tracked as CVE-2024-39431. This vulnerability can be exploited remotely before encryption and authentication procedures are established.

With one specially crafted packet, attackers can overflow the modem's stack and seize execution flow via Return-Oriented Programming (ROP) techniques. From here, researchers were able to manipulate the Android kernel on the Application Processor (AP) by exploiting internal SoC memory mappings and leveraging undocumented Direct Memory Access (DMA) peripherals for lateral movement.

Ultimately, the exploit chain allowed arbitrary code execution on both the modem and host OS—demonstrated by running the game Doom on the vehicle’s multimedia unit.

Why This Matters for CISOs

Connected vehicle fleets are part of modern enterprise operations—from logistics and smart cities to law enforcement and energy utilities. A compromise in modem firmware could allow adversaries to:

Hijack navigation or infotainment systems
Disrupt transport safety features
Exfiltrate or manipulate user and telemetry data
Persist across software patches due to firmware-level implants

CISOs must reassess the safety assumptions made around SoC and telematics systems within enterprise-managed vehicles. Security investments focused solely on OS and app-level protections now overlook critical hardware-integrated attack surfaces.

Governance implications are also severe. OEMs and fleet partners may be non-transparent regarding which exact SoCs they use—exposing organizations to unknown inherited risk. Regulatory compliance for fleet safety and consumer data protection may be jeopardized by such vulnerabilities.

Threat & Risk Analysis

Attack Vectors

Remote Wireless Exploits: CVE-2024-39431 can be triggered via crafted RLC protocol packets over 3G links—before secure channels are established.
Abuse of IoT Modem Interfaces: Leveraging AT command interfaces and undocumented DMA functions enabled cross-boundary control of application processors.
Supply Chain Exposure: Vehicles from multiple manufacturers use this chip; OEMs may rebrand or obscure SoC suppliers—masking your exposure.

Exposure Scenarios

Connected Fleets: Delivery, logistics, autonomous vehicles, and serviced cars equipped with affected modems.
Smart Infrastructure: Municipal transit, law enforcement vehicles with centralized fleet management apps.
User Privacy Risks: Infotainment units store PII, GPS histories, call logs—vulnerable to lateral exfiltration.

Supply Chain Relevance

Unisoc-based SoCs are often used in cost-sensitive vehicle platforms, primarily from Chinese manufacturers, increasingly exported across the globe. Many are unpatched or lack firmware update pipelines—creating lasting systemic risk.

For CISOs, this reveals a broader need for comprehensive patch management strategy that extends beyond desktop and server environments into mobile and vehicular systems.

Attacker Motivations

Espionage and Nation-State Surveillance
Targeted Fleet Disruption or Behavioral Tracking
Exploitation for Commercial or Political Gain
Demonstration of Prowess in Bug Bounties and Research Contests

Potential Enterprise Impact

Disruption of critical logistics services
Breach of sensitive GPS, call, or PII records from infotainment systems
Reputational damage through fleet compromise and media exposure
Regulatory noncompliance (e.g. GDPR, NHTSA)

For sustained monitoring, include related threat actors and firmware exploits into your daily cyber threat briefings.

MITRE ATT&CK Mapping

T1203 — Exploitation for Client Execution
RCE on the modem via malformed RLC packets.
T1499 — Endpoint Denial of Service
Causing reboots or instability of the head unit from remote payloads.
T1068 — Exploitation for Privilege Escalation
Used to elevate privileges within the SoC’s Android kernel.
T1027 — Obfuscated Files or Information
ROP chains and NAS protocol abuse concealed malicious code.
T1046 — Network Service Scanning
Modem functions exposed for discovery in connected environments.
T1086 — PowerShell (analogous AT command use)
Repurposed standard AT control interface for memory manipulation.

Key Implications for Enterprise Security

Reevaluate threat models for connected fleet assets.
Enforce hardware provenance for embedded system suppliers.
Scrutinize OTA and firmware update capabilities for vehicular SoCs.
Adopt incident response protocols covering modem-level exploits.
Require third-party attestations for supply chain firmware security.

Recommended Defenses & Actions

Immediate (0–24h)

Identify all fleet or embedded assets utilizing Unisoc-based SoCs.
Isolate affected vehicle models from sensitive networks.
Initiate vendor disclosure and patch communication with OEMs.

Short Term (1–7 days)

Deploy traffic monitoring on 3G/4G/UAV channels for anomalous RLC/NAS behavior.
Begin forensic review of infotainment units for signs of compromise.
Audit SoC-level access paths to ensure bootloader and firmware integrity.

Strategic (30 days)

Establish hardware SBOM mandates for fleet vendor contracts.
Insert contract clauses requiring firmware security update pipelines.
Include modem and SoC in endpoint detection and response scoping.
Integrate SoC attacks into red/blue team simulation exercises.

Conclusion

Connected vehicle modems are no longer benign silicon—they’re adversary entry points that live outside enterprise SIEM visibility. The CVE-2024-39431 flaw in Unisoc’s modem SoC serves as a stark warning that the chain of trust must include embedded firmware.

Enterprises with mobile, IoT, and automotive dependencies should expand their architecture reviews and third-party risk frameworks. Incorporate modem firmware verification into procurement and operations lifecycles, and treat vulnerabilities at the 3G protocol layer with the same urgency as public-facing APIs.

This daily briefing underscores the growing sophistication of firmware attacks and their reach into traditionally isolated systems. Ensure your fleet, partners, and suppliers are now part of your daily threat updates.

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