Cybersecurity analysts have identified a sophisticated attack method where threat actors utilize ephemeral port 60102 to establish covert channels for malware communication.
This technique, observed in a recent case study, demonstrates how attackers bypass traditional detection systems by exploiting nonstandard ports for HTTP services.
Ephemeral Ports: A New Frontier for Malicious Activity
In a recent incident, attackers initiated their operation with a brute-force password guessing attack on an SSH server.
Once access was gained, the attackers executed a complex command to download malware from an external server.
The malicious server, identified as 140.143.196.172 and hosted by Tencent Cloud Computing Co., Ltd in Shanghai, China, served files through HTTP over port 60102 an ephemeral port typically reserved for temporary communications rather than persistent services.
The attack leveraged multiple methods to retrieve the malware file, including curl, wget, and direct TCP socket connections.
These redundant techniques ensured the payload was successfully downloaded even if one method failed.
The use of port 60102 allowed the attackers to evade detection by automated scanning tools like Shodan and GreyNoise, which do not typically monitor ephemeral ports.
Challenges in Detecting Nonstandard Port Usage
The use of ephemeral ports for hosting malicious services poses significant challenges for cybersecurity defenses.
Tools like Shodan rely on predefined port lists for scanning public IPs, and port 60102 is not included in their standard set.
Similarly, GreyNoise collects data passively through honeypots and would only detect such activity if the malicious server directly interacted with its sensors.
According to ICS Report, this lack of visibility enables attackers to operate under the radar, using ephemeral ports as temporary access points for malware distribution.
The transient nature of these ports further complicates detection, as they are often opened and closed dynamically, leaving little trace.
To counter this threat, organizations must adopt proactive measures:
- Restrict Nonstandard Port Traffic: Implement firewall rules to block HTTP traffic over unconventional ports unless explicitly required.
- Enhance Credential Security: Enforce strong password policies and limit root access via SSH to reduce susceptibility to brute-force attacks.
- Monitor Anomalous Connections: Use intrusion detection systems (IDS) or endpoint protection solutions to flag unusual protocol-port pairings.
- Leverage Advanced Scanning Tools: Solutions like Censys’s Universal Internet DataSet can detect nonstandard protocol-port combinations through automatic protocol identification.
The exploitation of ephemeral ports like 60102 highlights a growing trend among cybercriminals to evade traditional detection mechanisms.
As automated scanning tools struggle to keep pace with these tactics, the onus falls on cybersecurity professionals to identify and mitigate such threats manually.
Enhanced monitoring and stricter network controls are essential to safeguard against this emerging vector of attack.
