Cisco Confirms Salt Typhoon Exploited CVE-2018-0171 in U.S Network

Recent revelations from Cisco have shed light on a sophisticated campaign by a Chinese threat actor, Salt Typhoon. This blog takes a deep dive into the details of the attack, the vulnerabilities exploited, and what organizations—preeminent U.S. telecommunications companies—can do to safeguard their networks against similar threats.

In this comprehensive discussion, we will explore the background of advanced persistent threats (APTs), how threat actors exploit known vulnerabilities and stolen credentials, and the advanced techniques they employ to remain undetected. We also outline best practices and recommendations for organizations seeking to bolster their cybersecurity posture.

Background on Advanced Persistent Threats and State-Sponsored Actors

Advanced persistent threats, or APTs, are characterized by their long-term presence in targeted networks and meticulous approach to evading detection. Unlike more opportunistic cyberattacks, APT campaigns are marked by their high degree of planning, persistence, and coordination. These campaigns often involve state-sponsored groups or highly skilled criminal organizations with significant resources at their disposal.

Salt Typhoon is one such threat actor that has come under scrutiny after Cisco’s Talos Intelligence Group confirmed that the group exploited a known vulnerability and used stolen credentials to infiltrate the networks of major U.S. telecommunications companies. The indicators of a well-coordinated, long-term operation—including maintaining access for over three years in one instance—highlight the sophisticated nature of this campaign.

The Exploitation of CVE-2018-0171 and Credential Theft

Exploiting a Known Vulnerability

At the heart of the Salt Typhoon campaign lies the exploitation of CVE-2018-0171—a known security flaw affecting Cisco devices. Vulnerabilities like these offer cyber adversaries an entry point into otherwise secured network environments. In this case, the flaw enabled the attackers to access critical network infrastructure remotely. By leveraging this vulnerability, the threat actor bypassed several layers of security that might otherwise have prevented unauthorized access.

The exploitation of CVE-2018-0171 underscores a common issue in network security: even known vulnerabilities, when left unpatched, can serve as gateways for determined attackers. This particular flaw, which has been publicly disclosed for several years, illustrates the importance of rigorous patch management and continuous monitoring of network systems.

The Role of Stolen Credentials

Equally critical to the attack’s success was using legitimate, stolen credentials. Instead of relying solely on technical exploits, Salt Typhoon combined a software vulnerability with the theft of valid login details. While the exact method of acquiring these credentials remains unclear, several potential vectors exist—from phishing campaigns to brute-force attacks against accounts with weak passwords.

Once inside the network, the attackers leveraged these credentials to move across different systems and devices laterally. By masquerading as authorized users, they could evade detection while accessing sensitive configurations and data. This dual-pronged approach—exploiting a technical vulnerability and leveraging stolen credentials—exemplifies the multi-faceted nature of modern cyberattacks.

Persistence and Lateral Movement within the Network

Maintaining Long-Term Access

One of the most striking revelations from Cisco’s investigation was the prolonged period during which the threat actor maintained access to compromised environments. Salt Typhoon persisted within a target network for over three years in at least one instance. Such longevity indicates the group’s ability to remain hidden while continually adapting their methods to avoid detection.

The attackers extensively used stealth techniques to achieve this and built a resilient foothold within the network. By continuously modifying their tactics and exploiting multiple vendor devices, they created an environment where their presence was virtually undetectable by conventional security measures.

Lateral Movement Using Trusted Infrastructure

A hallmark of advanced cyberattacks is the ability to move laterally within a network, exploiting trusted relationships between systems. In the Salt Typhoon campaign, the attackers were observed leveraging “living-off-the-land” (LOTL) techniques. Instead of deploying new tools that might trigger alarms, they abused legitimate processes and trusted infrastructure components to jump from one device to another.

For instance, compromised network devices were repurposed as intermediate relays. These devices, which were initially intended to facilitate routine operations, became the stepping stones for the adversary to access additional systems. In some cases, these intermediate devices served as the first hop for outbound data exfiltration operations, enabling the attackers to remain undetected for extended periods.

Advanced Techniques: Obfuscation and Log Manipulation

The Utility of JumbledPath

Among the sophisticated tools deployed by Salt Typhoon was a bespoke utility known as JumbledPath. This Go-based ELF binary allowed the threat actor to execute remote packet captures on Cisco devices through an actor-defined jump-host. By capturing network traffic remotely, the attackers could monitor data flows and gather further credentials or configuration details.

This utility was a means of data collection and a critical role in the attackers’ obfuscation strategy. By enabling the execution of commands from non-publicly reachable devices, JumbledPath helped mask the true origin of the malicious activity, complicating forensic investigations and hindering the identification of the attack’s source.

Clearing Logs and Disabling Logging

The attackers cleared logs and turned off mechanisms across compromised systems to cover their tracks. They significantly hampered forensic analysis efforts by periodically erasing critical files such as .bash_history, auth.log, last log, wtmp, and btmp. This deliberate log manipulation obscured the source and destination of their network requests, thereby delaying or even preventing incident response teams from piecing together the timeline of the intrusion.

The ability to erase digital footprints is a common tactic among state-sponsored groups and advanced threat actors. In the case of Salt Typhoon, this strategy further emphasizes the importance of adopting robust, multi-layered security measures that go beyond traditional logging and monitoring practices.

The Role of Cisco Talos in Uncovering the Threat

In-Depth Analysis and Ongoing Research

Cisco’s Talos Intelligence Group has been at the forefront of threat detection and analysis for years. Their investigation into the Salt Typhoon campaign provided crucial insights into the threat actor’s methods and tactics. By carefully analyzing network traffic, device configurations, and log files, Talos was able to piece together a comprehensive picture of the attackers’ movements within compromised networks.

One of Talos’s key findings was that the threat actor modified the loopback interface address on a compromised switch. This allowed the attacker to use the loopback interface as the source of subsequent SSH connections, effectively bypassing established access control lists (ACLs) on other devices. Such intricate maneuvers highlight the group’s technical prowess and underscore the need for organizations to remain vigilant in their security practices.

Coordination and Sophistication

The attack timeline suggests extraordinary coordination, planning, and patience—characteristics typically associated with state-sponsored APTs. This persistent approach, combined with multiple exploitation techniques and the ability to remain hidden for extended periods, indicates that Salt Typhoon is well-funded and highly strategic in its operations.

The group’s ability to target multiple vendors and adapt to various network environments further underscores its flexibility and technical expertise. As a result, the threat posed by such actors is not limited to any single industry or geographical region; rather, it represents a global challenge that requires a coordinated and proactive security response.

Broader Implications for the Telecommunications Sector and Beyond

Targeting Major U.S. Telecommunications Companies

Telecommunications companies are the backbone of modern connectivity, providing the infrastructure supporting the Internet, mobile communications, and data transfer. A breach in these networks can have far-reaching implications—not only for the companies themselves but also for the millions of end users who rely on their services daily. The targeting of major U.S. telecommunications companies by Salt Typhoon highlights the attractiveness of these networks to sophisticated threat actors.

A successful breach in such environments can lead to widespread disruptions, data exfiltration, and compromise in critical communications. In today’s hyper-connected world, the consequences of such intrusions extend far beyond the immediate impact on the targeted companies, potentially affecting national security, economic stability, and public trust in digital services.

The Risk of Abusing Trusted Network Devices

One of the more alarming aspects of this campaign is the abuse of trusted network infrastructure. By exploiting vulnerabilities in network devices and leveraging legitimate credentials, attackers can compromise systems that are integral to the smooth operation of an organization. This abuse of trusted devices not only facilitates lateral movement within the network but also provides an avenue for attackers to pivot into other areas, potentially reaching sensitive systems or exfiltrating critical data.

This scenario underscores the need for organizations to implement stringent security measures around network devices. Regular security audits, strict access controls, and comprehensive monitoring of device configurations are essential to detect and mitigate unauthorized changes that could indicate a compromise.

Best Practices for Securing Network Devices

In light of the evolving threat landscape exemplified by the Salt Typhoon campaign, organizations must take proactive steps to secure their network infrastructure. Below are several best practices that can help mitigate the risks associated with similar advanced attacks:

Regular Patch Management

Ensuring all network devices are running the latest firmware and software updates is critical. Vulnerabilities like CVE-2018-0171 are known entry points for attackers, and timely patching can significantly reduce the attack surface. Organizations should establish a routine patch management schedule and prioritize updates for devices most critical to network operations.

Strengthening Credential Policies

Since stolen credentials played a central role in the Salt Typhoon campaign, enforcing strong credential policies is imperative. This includes using complex passwords, implementing multi-factor authentication (MFA), and regularly updating access credentials. Additionally, organizations should conduct periodic reviews of user accounts and immediately revoke access for inactive or compromised accounts.

Enhanced Network Monitoring and Logging

Given the sophisticated log manipulation techniques the attackers employ, maintaining robust logging and monitoring systems is essential. Organizations should deploy solutions that provide real-time alerts and can detect anomalies in network traffic. Centralized logging and regular audits can help identify suspicious activities before they escalate into a full-blown breach.

Segmentation and Least Privilege Access

Network segmentation can limit the lateral movement of attackers within an environment. By dividing the network into isolated segments and enforcing strict access controls, organizations can contain potential breaches and minimize the damage caused by a compromised device. Implementing the principle of least privilege—where users and devices are given only the access necessary for their function—can further reduce the risk of unauthorized access.

Regular Security Audits and Penetration Testing

Regular security audits and penetration tests can help organizations identify vulnerabilities before attackers exploit them. These assessments should cover all aspects of the network, including device configurations, authentication mechanisms, and firewall rules. Organizations can strengthen their defenses against sophisticated threat actors like Salt Typhoon by proactively addressing identified weaknesses.

Looking Ahead: The Future of Cyber Defense

The Evolving Tactics of Threat Actors

The Salt Typhoon campaign is a stark reminder of the continuous evolution of cyber threats. As attackers become more adept at combining technical exploits and social engineering techniques, the need for a dynamic and adaptive cybersecurity strategy becomes increasingly apparent. Organizations must remain agile, updating their security protocols and technologies to stay ahead of adversaries constantly refining their methods.

Investing in Threat Intelligence

In today’s complex threat landscape, investing in threat intelligence is crucial. Organizations should collaborate with cybersecurity firms and leverage platforms that provide real-time insights into emerging threats. By staying informed about the latest attack vectors and tactics, companies can better prepare for and respond to potential breaches.

Fostering a Culture of Cybersecurity

Beyond technology and processes, a strong cybersecurity culture is essential. Employees at all levels must be educated about the risks of phishing, social engineering, and other common attack vectors. Regular training sessions, awareness campaigns, and simulated phishing exercises can help build a more resilient workforce better equipped to identify and report suspicious activities.

Conclusion: Staying Vigilant in an Era of Advanced Threats

The revelations surrounding the Salt Typhoon campaign are a critical wake-up call for organizations worldwide. By exploiting known vulnerabilities like CVE-2018-0171 and leveraging stolen credentials, sophisticated threat actors can gain prolonged access to essential networks, often without detection. The multi-layered approach employed by Salt Typhoon—ranging from advanced persistence techniques to log obfuscation—highlights the pressing need for organizations to adopt a comprehensive and proactive cybersecurity strategy.

Organizations, particularly those in critical sectors such as telecommunications, must prioritize regular patch management, enforce stringent credential policies, and deploy robust monitoring and logging systems. Additionally, fostering a culture of cybersecurity and investing in threat intelligence will be vital to countering the ever-evolving tactics of state-sponsored and highly sophisticated threat actors.

By understanding the methods used by groups like Salt Typhoon and implementing best practices for network security, companies can protect their valuable assets and contribute to a more secure digital environment for everyone. As cyber threats continue to evolve, the collective efforts of organizations, security professionals, and industry leaders will be key to maintaining the integrity and reliability of our global communications infrastructure.

In this ongoing battle against cyber adversaries, staying informed, prepared, and vigilant is not just an option—it is an imperative for the continued resilience of our digital society.

Organizations can better navigate the challenges of advanced persistent threats with a clear understanding of the threat landscape and practical steps to bolster network defenses. Cisco Talos’ detailed insights into the Salt Typhoon campaign underscore the importance of continual vigilance, comprehensive security practices, and an adaptive approach to cybersecurity in an increasingly interconnected world.

Ultimately, the lessons learned from this campaign should catalyze change within the cybersecurity community. By embracing a proactive mindset and investing in robust defensive measures, organizations can mitigate the risk of future intrusions and ensure that critical infrastructures remain secure against even the most advanced threat actors.

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