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In the ongoing battle between cybersecurity defenders and malicious actors, honeypots play a vital role in revealing the tactics and behaviors of attackers. One cybersecurity researcher, Jesse La Grew, set up a group of DShield honeypots to collect and analyze malicious traffic. Over a year of detailed logging across SSH, Telnet, web interfaces, firewalls, and packet captures has uncovered a startling trend: attackers are aggressively abusing the passwd command in attempts to change passwords and gain deeper system access.
The article explores this phenomenon in-depth, explaining how nearly 94% of the 536,508 unique commands submitted to the honeypots involved passwd. This triggered an effort to cluster the data into meaningful groups to understand attackersâ strategies and isolate outliers that might reveal more advanced techniques.
Password Change Attempts Dominate Attacker Behavior
Over a year of data collection from DShield honeypots revealed that most attack commands are focused on gaining or modifying access through password changes. Among the 536,508 unique commands logged by Cowrie (an SSH/Telnet honeypot), a staggering 502,846 included the passwd commandâ93.73% of all commands submitted.
Due to the overwhelming volume, the researcher opted to filter out passwd-based commands to study other patterns without crashing their script. They processed this massive dataset by alphabetically sorting commands and selecting every third entry, which helped manage memory limitations.
Through this filtering method, 17 distinct clusters of passwd-based commands emerged. These ranged from straightforward echoing of passwords into passwd, to more complex chains that included CPU checks, downloading remote bots, modifying SSH configurations, and adding privileged users. For instance:
One cluster used openssl passwd to create hashed passwords on the fly.
Others combined password changes with system reconnaissance commands and backdoor user creation.
Notably, some attackers leveraged automated scripts to reset root passwords, install SSH keys, modify firewall rules, and restart SSH servicesâall part of a broader persistence strategy.
Outliers uncovered even more sophisticated tactics. One script discovered on September 13, 2024, used elaborate bash scripting to create root-level users, harvest system information, insert SSH backdoors, and alter /etc/ssh/sshd_config to restrict legitimate remote access. The command originated from a single IP and stood out as a one-time use script, likely hand-deployed.
The analysis concluded that while clustering helps group general behavior, the true gold lies in identifying rare, unique samples. These reveal custom scripts and attacker ingenuity that would otherwise go unnoticed in bulk analysis.
What Undercode Say:
The massive presence of the passwd command in honeypot logs highlights a key observation in modern cyberattacks: attackers are no longer content with just exploiting vulnerabilitiesâthey are increasingly focused on maintaining long-term access and control. This behavior reflects a shift from opportunistic attacks to persistent threats, where password manipulation plays a central role in lateral movement and privilege escalation.
From an analytical perspective, clustering the commands into 17 groups is a commendable effort to reduce noise and surface patterns. The use of alphabetic sorting and sampling every third command is a clever, if imperfect, strategy to avoid memory issues during data processing. While some clusters may have lost granularity due to this sampling method, the broader picture remains intactâthereâs a clear, structured attempt by attackers to automate user manipulation and maintain persistence.
More alarming is the discovery of an elaborate SSH âvaccineâ script designed to create a root-level user with stealth capabilities, manipulate SSH configurations, and establish remote access paths. This is not random noise or script-kiddie behaviorâitâs calculated, persistent, and clearly tailored to specific targets. The fact that this command only appeared once makes it even more critical. It likely belonged to a sophisticated actor conducting reconnaissance or testing deployment before broader usage.
This reinforces a key idea in cybersecurity: the rare eventsâthe outliersâoften matter more than the bulk trends. While 94% of commands using passwd suggest a pattern, itâs the 0.0002% that may signal a more dangerous and targeted threat.
Moreover, the tendency to chain commands like lscpu, uname, and wget with passwd shows attackers are scripting entire exploitation workflows. These workflows include system profiling, download and execution of malware, and firewall evasion. It reflects a deep understanding of Linux environments and a goal of persistence and stealth.
This analysis also raises an important point for security teams using honeypots: memory and processing limitations shouldn’t hinder the investigation of vast datasets. Instead, sampling strategies, feature tuning, and targeted filters should be integrated early into the honeypot logging architecture.
Overall, this study shows that attackers are getting smarter, and defenders must evolve faster. Basic command clustering isnât just about categorizing logsâitâs about identifying emerging TTPs (Tactics, Techniques, and Procedures) before they go mainstream.
Fact Checker Results â
Over 500,000 unique commands analyzed from honeypots đ
94% of commands attempted to use `passwd` đ ïž
Only one custom SSH backdoor script identified in outliers đ§
Prediction đź
Given the strategic use of the passwd command, future attacks on Linux systems will likely see an increase in:
Custom rootkit deployment with dynamic password resets
Obfuscated command chains embedded in memory-only payloads
Honeypot evasion techniques using randomized command patterns
Security researchers should prepare for evolving command-line obfuscation and hybrid techniques that merge password resets, privilege escalation, and network manipulation into single-pass scripts.
References:
Reported By: isc.sans.edu
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