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Introduction:
Sysdig is a powerful open-source tool that provides deep system-level visibility into Linux environments, capturing kernel events and system calls in real time. Unlike traditional monitoring solutions, Sysdig acts like a “strace + tcpdump + lsof + top + htop” combined, enabling security teams to troubleshoot performance issues and detect anomalies such as unauthorized process execution or unexpected network connections. With containerized workloads and cloud-1ative infrastructures becoming prime attack targets, mastering Sysdig is essential for blue teams, incident responders, and DevOps engineers.
Learning Objectives:
- Install and configure Sysdig on major Linux distributions for real-time system visibility.
- Use Sysdig’s chisels and filters to detect suspicious processes, file changes, and network behaviors.
- Apply Sysdig for container security forensics and integrate with Falco for runtime threat detection.
You Should Know:
- Installing Sysdig and Capturing System Activity Like a Pro
Sysdig leverages a kernel module or eBPF probes to capture system calls without significant overhead. Here’s how to get started on Ubuntu/Debian and RHEL/CentOS, along with basic capture commands.
Step‑by‑step installation guide:
Ubuntu/Debian:
sudo apt update sudo apt install -y gnupg lsb-release curl -s https://s3.amazonaws.com/download.draios.com/DRAIOS-GPG-KEY.public | sudo apt-key add - sudo curl -s -o /etc/apt/sources.list.d/draios.list https://s3.amazonaws.com/download.draios.com/stable/deb/draios.list sudo apt update sudo apt install -y sysdig
RHEL/CentOS/Fedora:
sudo rpm --import https://s3.amazonaws.com/download.draios.com/DRAIOS-GPG-KEY.public sudo curl -s -o /etc/yum.repos.d/draios.repo https://s3.amazonaws.com/download.draios.com/stable/rpm/draios.repo sudo yum install -y sysdig or dnf on Fedora
Verify installation:
sysdig --version
Capturing live events:
To watch all system calls in real time (similar to `strace -p` but system‑wide):
sudo sysdig
To capture only file writes under `/etc`:
sudo sysdig "evt.type=write and fd.name contains /etc"
Save a 30‑second trace to a file for later analysis:
sudo sysdig -w capture.scap -M 30
Replay the capture:
sysdig -r capture.scap
Windows equivalent:
While Sysdig is Linux‑native, Windows defenders can use ProcMon (Process Monitor) from Sysinternals for file/registry/process monitoring, or deploy Sysdig’s Windows agent (commercial offering) for unified visibility.
2. Mastering Sysdig Filters for Threat Hunting
Sysdig’s filter language allows granular querying of system call attributes. Common security use cases include detecting reverse shells, privilege escalations, and crypto miners.
Step‑by‑step threat hunting examples:
- Detect any process spawning a shell with network connection (potential reverse shell):
sudo sysdig "proc.name = bash and evt.type = execve and fd.type = ipv4"
-
Find unexpected outbound connections from a webserver (e.g., data exfiltration):
sudo sysdig "fd.sip != '127.0.0.1' and fd.sport = 443 and proc.name != nginx"
-
Monitor for file writes to sensitive directories like `/root/.ssh` or `/tmp` with unusual names:
sudo sysdig "fd.name contains /root/.ssh and evt.type = write"
-
Capture all `sudo` or `su` elevation attempts:
sudo sysdig "proc.name in (sudo, su) or evt.arg contains 'sudo'"
Creating a real‑time alert with a simple script:
Save the following as `detect_reverse_shell.sh`:
!/bin/bash sudo sysdig -p "%proc.name %fd.sip %fd.sport" "evt.type=connect and proc.name=bash" | while read line; do echo "[!] Suspicious outbound bash connection: $line" Optionally send to SIEM via curl done
Run it in a screen session for continuous monitoring.
- Using Sysdig Chisels – Pre‑built Security Forensics Tools
Chisels are Lua scripts that transform raw syscall data into actionable reports. They are located under /usr/share/sysdig/chisels/.
Step‑by‑step guide to essential chisels:
– `topfiles_bytes` – shows files with the most I/O activity (detect ransomware or log tampering):
sudo sysdig -c topfiles_bytes
– `spy_user` – spy on a specific user’s commands (like `pam_tty_audit` but richer):
sudo sysdig -c spy_user -u leonard
– `netstat` – list all active network connections at capture time:
sudo sysdig -c netstat
– `httplog` – logs HTTP requests and responses (useful for debugging web apps and spotting injections):
sudo sysdig -c httplog
– `list_login_shells` – displays all login shell invocations (audit for unauthorized shells):
sudo sysdig -c list_login_shells
Creating your own chisel:
Copy an existing chisel and modify it. For example, to create a `detect_cryptominer.lua` that flags high CPU syscalls from unknown processes, reference Sysdig’s developer docs. The command to run a custom chisel:
sudo sysdig -c /path/to/detect_cryptominer.lua
- Integrating Sysdig with Falco for Runtime Container Security
Falco, originated by Sysdig, is the CNCF runtime security tool that uses Sysdig’s kernel instrumentation. You can feed Sysdig captures into Falco rules for automated incident response.
Step‑by‑step Falco integration:
Install Falco (using Helm on Kubernetes or directly on Linux):
Kubernetes (Helm) helm repo add falcosecurity https://falco.org/charts helm install falco falcosecurity/falco --set falco.jsonOutput=true Linux (Debian) curl -s https://falco.org/repo/falcosecurity-packages.asc | sudo apt-key add - echo "deb https://download.falco.org/packages/deb stable main" | sudo tee /etc/apt/sources.list.d/falcosecurity.list sudo apt update && sudo apt install -y falco
Run Falco and output to Syslog or JSON:
sudo falco -o json_output=true
Write a custom Falco rule to detect privilege escalation via `setuid` binaries (e.g., `pkexec` exploitation):
- rule: Suspicious setuid Binary Execution desc: Detect execution of a setuid binary from a non‑standard location condition: > spawned_process and proc.name in (pkexec, sudo, su) and (proc.pname not in (systemd, login, bash, init) or fd.directory not in (/bin, /usr/bin)) output: "Setuid execution detected (user=%user.name command=%proc.cmdline)" priority: WARNING
To replay a Sysdig capture with Falco:
sudo falco -r capture.scap
This enables offline forensics of past incidents.
5. Cloud Hardening with Sysdig for Kubernetes Clusters
Sysdig offers Sysdig Secure (commercial) but open‑source users can still leverage Sysdig Inspect (GUI for .scap files) and kubectl‑sysdig plugin for container troubleshooting.
Step‑by‑step Kubernetes visibility:
Install the kubectl plugin:
curl -LO https://github.com/draios/sysdig/raw/master/scripts/kubectl-sysdig chmod +x kubectl-sysdig sudo mv kubectl-sysdig /usr/local/bin/
Capture system calls from a specific pod:
kubectl sysdig -1 default my-pod -w pod_capture.scap
Analyze pod network connections:
sudo sysdig -r pod_capture.scap -c netstat
Linux commands to harden container runtime:
- Restrict `ptrace` syscall in seccomp profiles (prevents process injection):
{ "defaultAction": "SCMP_ACT_ALLOW", "syscalls": [{ "names": ["ptrace"], "action": "SCMP_ACT_ERRNO" }] }
Apply via Docker: `–security-opt seccomp=/path/to/profile.json`
- Drop all capabilities except `NET_ADMIN` for network monitoring containers:
docker run --cap-drop=ALL --cap-add=NET_ADMIN your-image
Windows counterpart:
Use Docker for Windows with Linux containers and the same seccomp profiles, or leverage Microsoft’s Sysmon for system call monitoring on Windows hosts.
What Undercode Say:
- Key Takeaway 1: Sysdig is not just a troubleshooting tool – it’s a forensic goldmine. By capturing every system call, you can replay security incidents like a DVR, answering “what command ran at 02:14 AM from which PID?” without needing EDR agents on every node.
- Key Takeaway 2: Combining Sysdig with Falco transforms reactive logging into proactive runtime defense. Teams should practice writing custom Falco rules from Sysdig capture samples to detect zero‑day behaviors (e.g., a non‑root process writing to
/etc/cron.d).
Analysis (10 lines):
The post by Lancer InfoSec University highlights Sysdig as a “system visibility and troubleshooting” tool, but its real value for cybersecurity is in incident response and threat hunting. Many organizations rely solely on agent‑based EDR, which misses kernel‑level events. Sysdig fills that gap with near‑zero overhead and offline replay capability. The provided GitHub link (https://github.com/draios) leads to the official Sysdig repository, which includes Falco, the Sysdig CLI, and container security tools. Lancer InfoSec’s call to action (“Follow us for quick, actionable cyber guidance”) suggests they are positioning Sysdig as a core skill for their training courses – likely in their upcoming cloud security or IR certification tracks. For defenders, mastering the sysdig filters and chisels listed above is equivalent to learning a new incident response language. The only caveat is the learning curve; but once you internalize the event format (fd.name, evt.type, proc.name), you can hunt across thousands of events in seconds. The future of open‑source security lies in tools like Sysdig that give full transparency without vendor lock‑in.
Prediction:
- +1 Open‑source Sysdig will increasingly replace proprietary agents in Kubernetes environments, driven by eBPF adoption and zero‑trust mandates. Expect more training courses (like Lancer InfoSec’s) to integrate Sysdig labs for SOC analysts.
- +1 Integration with AI log analyzers will automate chisel creation: natural language queries like “show me all failed sudo attempts” will generate Sysdig filters on the fly, accelerating threat hunting.
- -1 As Sysdig gains popularity, attackers will develop evasion techniques targeting its kernel module (e.g., hooking the same syscalls to hide processes). Defenders must combine Sysdig with memory forensics (Volatility) for complete coverage.
- -1 Commercial versions of Sysdig (Secure, Cloud) may limit advanced features behind paywalls, pushing open‑source users to maintain their own rule sets and integrations – increasing operational overhead for small teams.
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