Path Traversal 2.0: Escaping Containers and Reading /etc/passwd in 2025 📁

---

Introduction

In 2025, the classical web vulnerability known as Path Traversal (also called directory traversal) has evolved significantly: modern attack surfaces now include container-environments, archive extraction paths, and cloud-native workflows. What once was mostly a web-app trick of “../../etc/passwd” now extends into container escapes, arbitrary file writes inside container images, and privileged configuration file overwrites. This article explains why Path Traversal 2.0 matters, how attackers are using it to escape containers and read or overwrite files such as /etc/passwd, and what you must do today to defend yourself.

---

What is Path Traversal?

At its core, a path traversal attack allows an attacker to manipulate file path logic (via ../, absolute paths or encoded variants) so that the application accesses files outside its intended directory or “root”. For web-apps, that might mean reading /etc/passwd, source code, or configuration files. (owasp.org)

Classic example

Imagine a web application with a URL parameter like ?file=report.pdf which is passed to open("/var/www/files/"+filename). If the code fails to sanitize filename, the attacker might supply ../../../../etc/passwd and cause the server to return the system’s password file. (invicti.com) The famous example from the OWASP page:

GET /vulnerable.php?file=../../../../etc/passwd

which reveals passwd entries like root:x:0:0:. (owasp.org)

Why it still matters

Despite being a relatively “old” class (it’s referenced by OWASP and has been known for decades), path traversal remains relevant because:

• Many applications still allow file path parameters or exports without strict validation. (yeswehack.com)
• Attackers now combine it with other bugs (e.g., SSRF, archive extraction vulnerabilities) to augment impact. (yeswehack.com)
• The move to containers, microservices and cloud native introduces new contexts (archive unpacking, container escapes) where traversal logic may be flawed.

---

Why “2.0”? The Evolution into Containers & Cloud

In 2025 the major shift is that path traversal vulnerabilities are no longer confined to simple web directory contexts. Instead we see:

Container & archive extraction vulnerabilities

• A recent vulnerability, CVE‑2025‑62156, affects Argo Workflows (a container-native workflow engine). The issue: during artifact extraction (untar/zip), entries in the archive can include traversal paths (or absolute paths) that escape the intended extraction directory, allowing writes into /etc/passwd, /etc/hosts, /etc/crontab inside the container. (OffSeq Threat Radar)
• Container escape attacks exploit the layered file-system model of containers and often combine with traversal logic or archive extraction. For example, a research paper “gh0stEdit” (June 2025) shows how an attacker could modify layers in a Docker image undetected. (arXiv)

Why /etc/passwd remains a focal point

• The file /etc/passwd on Unix‐based systems lists user accounts and metadata. Reading it doesn’t automatically give you hashed passwords these days (they’re often in /etc/shadow), but it reveals user names, UID/GIDs, shells, home directories—information useful for further attack steps and privilege escalation. (invicti.com)
• In container contexts, writing or overwriting /etc/passwd inside the container means you can inject a user or escalate privileges inside the container, which may then allow sandbox escape or host pivoting.

Microservices, APIs & internal file-shares

Modern applications in 2025 commonly expose internal APIs, microservices, or file‐fetch endpoints. Attackers target those endpoints for traversal, especially when they accept JSON input or internal requests that bypass outer filters. A guide published in May 2025 outlines how to probe APIs and bypass filters to chain traversal into internal reads. (yeswehack.com)

---

Attack Vectors: How Path Traversal 2.0 Works

Let’s break down how an attacker might exploit the evolved path traversal threat in 2025:

1. Basic file read via web app

• Find an endpoint accepting a filename or path parameter (common names: file, path, doc, img, download). (System Weakness)
• Try simple payloads: ../../../../etc/passwd, ../etc/passwd, path with null bytes or double encoding (..%2f..%2fetc/passwd). (owasp.org)
• If you succeed, you might read /etc/passwd – reveal user info, then plan subsequent steps for credentials, local file disclosure or code read.

2. Archive extraction / Zip Slip inside container

• The target component unpacks or extracts an archive (zip, tar, tar.gz) inside a container or host, but fails to validate each entry’s path.
• The malicious archive includes a file entry with a path like ../../../../etc/passwd or absolute /etc/passwd.
• On extraction, the file ends up in container system path (or sometimes host path) because the logic simply uses dest + header.Name after clean(), without checking directory‐escape.
• In CVE-2025-62156, this logic existed in Argo Workflows’ executor.go: filepath.Join(dest, filepath.Clean(header.Name)) but lacked check that header.Name stayed inside dest. (OffSeq Threat Radar)
• Result: attacker overwrites or writes /etc/passwd, giving them control over user accounts in that container context. From there: container escape, privilege escalation, lateral movement.

3. Internal/side-channel traversal in microservices

• An internal microservice accessible only from inside the network receives a JSON body like { "path": "reports/2025.csv" }.
• Attackers mis-route traffic via SSRF or proxy to hit that microservice, send payloads like ../../../../etc/passwd.
• They leverage the fact that internal services often have weaker filtering. The May 2025 guide shows this methodology. (yeswehack.com)

4. Container image layer abuse & escape

• Although not pure “../etc/passwd” scenario, attackers exploit container layering and file-system layering flaws to inject malicious files into image layers (see “gh0stEdit” paper). (arXiv)
• A traversal/flawed unpacking path combined with container privilege mis-configurations can lead to host escape or root in container.

---

Real-World Examples & Recent CVEs (2025)

Here are concrete recent vulnerabilities that reflect Path Traversal 2.0 in action:

• CVE-2025-62156 (Argo Workflows) — High severity; allows arbitrary file creation/overwrite such as /etc/passwd inside container via Zip Slip path traversal in artifact extraction. (OffSeq Threat Radar)
• CVE-2025-41242 (Spring Framework) — Medium severity; path traversal vulnerability in Spring when deployed on non-compliant Servlet containers serving static resources. (Home)
• CVE-2025-30208 (Vite dev server) — Arbitrary file read in Vite dev server via @fs path alias, enabling path traversal. (OffSec)

These point to the fact that even in 2025, path traversal remains both prevalent and evolving.

---

Why Reading /etc/passwd is Still a Big Deal

You might ask: “Ok, reading /etc/passwd – so what?” Here’s why it remains a meaningful goal for attackers, especially in container/host contexts.

• User enumeration: The file reveals usernames, UIDs, shells and home directories. That can help attackers pick privileged accounts (UID 0 = root) or special accounts.
• Privilege escalation: If the attacker can read /etc/passwd and then find a writable /etc/shadow (or other mis-config), or inject a user account via overwrite, they may escalate.
• Persistence & container escape: Overwriting /etc/passwd inside a container allows attacker to create a root user inside the container. If container privileges are not tightly isolated, this may lead to host escape.
• Template for further moves: Access to /etc/passwd can expose local hosts, service accounts, or aid pivoting to access internal networks.

In container environments, path traversal or malicious archive extraction leading to /etc/passwd writes is especially potent.

---

Querying the Threat Surface: Containers, Cloud & Workflows

Let’s zoom out and consider why the container/cloud environment increases risk.

Containerization increases the blast radius

Containers by design isolate processes, but many deployments still allow container processes to run as root, have mount privileges, or share host namespaces. If an attacker escapes via path traversal (e.g., write to /etc/passwd, load a root user), they can gain root in that container. From there, lateral movement to host or other containers is possible (especially in multi-tenant environments).

Archive/Zip extraction is a common “latent” vector

Many microservices or workflows accept uploaded artifacts, zipped logs, stored backups, or container layers. If the extraction code doesn’t sanitize entry paths (Zip Slip or path traversal in archives), attackers craft malicious archives to write files outside intended extraction directory. The Argo Workflows vulnerability demonstrates this clearly: malicious archive → escape directory → write to /etc/passwd. (OffSeq Threat Radar)

Trust boundaries shift in cloud‐native stacks

Modern systems rely on many layers: CI/CD pipelines, artifact stores, container registries, cloud object stores, orchestration engines. Attackers target less-secure components (e.g., an artifact store) to supply malicious archive that gets consumed by the pipeline and deployed to production. A path traversal bug at any extraction step becomes a serious escape vector. Additionally, research (“Characterizing Trust Boundary Vulnerabilities in TEE Containers”, Aug 2025) shows that some containers designed for Confidential Computing fail to enforce isolation properly—opening doors for traversal or escape. (arXiv)

---

Detecting & Exploiting Path Traversal in Modern Systems

Here are practical steps (for red-teams/pen-testers) to detect and evaluate path traversal & container escape scenarios:

Detection checklist

• Identify endpoints that accept file path / name / download / view / export / archive parameters. Example param names: file, path, template, doc, report. (System Weakness)
• Baseline: issue a request with a known safe file and observe response (status code, size, content).
• Use payloads: ../../../../etc/passwd ..\..\..\..\etc\passwd %2e%2e/%2e%2e/%2e%2fetc/passwd /etc/passwd

Per OWASP: pay attention to encoding, null bytes (%00), double encoding etc. (owasp.org) * For archive extraction: upload or trigger an extraction job with a crafted archive containing ../../../../etc/passwd or absolute path /etc/passwd entries. Then check if the file appears in container’s file system or if service responds differently. * In container/CI/CD context: monitor container creation logs, file writes, filesystem escapes. Use host-side inspection to see if /etc/passwd or other system files got modified.

Exploitation & impact assessment

• If you can read /etc/passwd, capture its contents and look for privileged accounts (UID 0, root).
• If you can write/overwrite /etc/passwd, you might insert a root user, change shell to /bin/bash, etc. Then attempt to spawn shell or escalate.
• In container context: once you have root in container, try mount, cat /proc/1/ns/mnt, docker exec, or discover host mounts or privileges that allow host escape.
• Map the environment: look for /proc/self/environ, /proc/mounts, /proc/net/tcp etc (classic follow-on from path traversal). (invicti.com)

Bypass techniques

• Use encodings: %2e%2e/, ..%2f, double encoding, null byte %00 (depending on environment). (owasp.org)
• Use alternative separators: Windows ..\ vs Unix ../.
• Increase traversal depth: sometimes the application blocks patterns at certain depth; bump to 6-12 levels. (System Weakness)
• Chain with SSRF or misconfigured proxies: send traversal payloads via internal endpoints. (yeswehack.com)

---

Mitigation & Best Practices for 2025

To defend against Path Traversal 2.0 attacks — especially in container/CI/CD/cloud contexts — adopt a layered approach:

Input validation & path sanitization

• Avoid using user-controlled input directly to build file paths. Prefer whitelisting of allowed filenames or directory names. (invicti.com)
• For file paths, use functions like realpath() or equivalent to resolve the absolute path, then verify that it is within the intended base directory. (yeswehack.com)
• Do not rely solely on blacklist filtering for ../, ..\\, or encoding patterns—these can be bypassed. (invicti.com)

Secure archive/unc­packing logic

• When unpacking archives (zip, tar) in containers or workflows, validate that each entry’s target path is inside the intended extraction directory. E.g., do not simply join dest + clean(entry.name) without further checks. As seen in CVE-2025-62156. (OffSeq Threat Radar)
• Consider using extraction libraries that enforce “no traversal” by default, or implement custom logic to check that resolved_path.startsWith(dest_dir).
• Run extraction in a non-privileged container (least privilege), read-only root filesystem when feasible, and drop excessive container capabilities.

Container / Host runtime protections

• Configure containers to run as non-root wherever possible.
• Use read-only root filesystems for containers that don’t need write access to host file system.
• Apply Kubernetes PodSecurityPolicies (or equivalent in your orchestrator) to restrict volume mounts, host namespace access, privilege escalation, hostPath mounts.
• Monitor for unexpected file modifications: e.g., /etc/passwd, /etc/shadow, /etc/hosts, binaries, or changed permissions. Research indicates high-performance VM introspection file monitoring for containers is emerging. (arXiv)
• Keep the container orchestration and workflow engines updated. For example, upgrade Argo Workflows to versions 3.6.12 or 3.7.3 to remediate CVE-2025-62156. (OffSeq Threat Radar)

Secure CI/CD pipeline & artifact handling

• Validate uploaded artifacts—archive files should be scanned and sanitized before automatic extraction.
• Limit internal artefact stores and extraction services to trusted origins; avoid public uncontrolled uploads that lead to internal consumption.
• Enforce supply chain security: container image signing, immutable registries, layer scanning for malicious modifications (see “gh0stEdit” threat). (arXiv)

Monitoring, logging & incident response

• Enable logging on file operations in containers (especially creation/writes in system directories).
• Use runtime security tools (Runtime Application Self-Protection, Host Intrusion Detection Systems) to detect abnormal behavior like writing to /etc/passwd or loading an unexpected shell.
• Regularly scan your systems using DAST/SAST for path traversal vulnerabilities. (invicti.com)

---

SEO-Friendly Wrap-Up: Key Takeaways

• Path Traversal 2.0 is not just old “../../etc/passwd” in web apps—it’s container escapes, archive unpacking bugs, workflow engines and cloud-native microservices.
• Reading or overwriting /etc/passwd remains a valid high-impact vector: enumeration, privilege escalation, container breakouts.
• Recent CVEs (e.g., CVE-2025-62156 in Argo Workflows) exemplify this evolution.
• Detection requires modern techniques: probing archive extraction endpoints, internal APIs, container file systems.
• Mitigation must span input validation, secure unpacking, container isolation, artifact pipeline hardening, and runtime monitoring.
• In 2025’s cloud-native era, path traversal is no longer “just a web bug”—it’s a platform-level threat.

---

Final Words

Whether you’re a developer building web services, a DevOps engineer managing container infrastructure, or a security professional auditing modern pipelines—the threat from path traversal has evolved. The key is to treat file access boundaries as trust boundaries: if user-controlled input or unchecked archives can dictate file paths, you’re exposing yourself. Even a simple “read /etc/passwd” may be the first step in a full container escape.

Stay vigilant. Raise awareness. Audit your extraction logic, container permissions, and internal APIs. Because in 2025, Path Traversal 2.0 is real—and the stakes are higher than ever.

---

Meta note (for SEO) Focus keywords: path traversal 2025, container escape traversal, /etc/passwd read container, Zip Slip container vulnerability, CVE 2025 path traversal, directory traversal modern api. Use H2 headings for clarity, bullet lists to enhance readability, and link to updated CVEs and academic research for authority.

---

Disclaimer: This article is for educational purposes only. Always obtain permission before testing systems for vulnerabilities.