Skip to content

README.md

Latest commit

 

History

History
253 lines (179 loc) · 9.57 KB

README.md

File metadata and controls

253 lines (179 loc) · 9.57 KB
Raw

php2shellbt

Python 3.6+ MIT License CVE-2026-109618 CVE-2026-109619 No external dependencies

php2shellbt is a standalone Python scanner that detects the php2shell vulnerability chain in PHP web applications — with zero external dependencies (pure stdlib).

What is php2shell?

php2shell is a critical vulnerability chain that combines PHP session management weaknesses to achieve unauthenticated Remote Code Execution (RCE) without writing any file to disk:

upload_progress use-after-free / OOM
         │
         ▼
  Session file injection (PHP code embedded in filename field)
         │
         ▼
  Local File Inclusion (LFI) of the session file
         │
         ▼
         RCE ← PHP code in session file executed by the server

Two new CVEs were assigned to the root causes of this chain:

CVE Title Affected PHP Fixed in
CVE-2026-109618 Session upload_progress use-after-free / OOM 5.4.0 – 8.5.11 8.2.35 / 8.3.36 / 8.4.27 / 8.5.12
CVE-2026-109619 var_destroy use-after-free (UAF) via unserialize() + destructor gadget 5.4.0 – 8.5.11 8.2.35 / 8.3.36 / 8.4.27 / 8.5.12

Vulnerability Details

CVE-2026-109618 — Session upload_progress use-after-free / OOM

When session.upload_progress.enabled = On (default in PHP ≥ 5.4), an attacker can supply a crafted PHPSESSID cookie in a multipart POST request containing the magic key PHP_SESSION_UPLOAD_PROGRESS. PHP creates (or reuses) a session file at the attacker-controlled path, storing the upload_progress data — including the multipart filename — verbatim in the session file. If cleanup is disabled (session.upload_progress.cleanup = Off), the session file persists indefinitely.

Conditions required:

  • session.upload_progress.enabled = On (default)
  • session.upload_progress.cleanup = Off OR a race-condition window
  • An LFI vulnerability that can include /tmp/sess_<PHPSESSID>

CVE-2026-109619 — var_destroy use-after-free

A var_destroy() use-after-free in PHP's unserialize path allows an attacker who controls a serialized object to trigger arbitrary destructor gadgets during the free phase. Combined with a POP (Property Oriented Programming) chain, this can yield RCE without any filesystem interaction.

Detection: The PHP version is leaked via the X-Powered-By: PHP/x.y.z response header. If the version falls within the affected range, the target is potentially vulnerable.

php2shell Handler Mismatch

When two PHP endpoints on the same application use different session.serialize_handler values (php_serialize on one endpoint, php on another), an attacker can write a malicious serialized object via the first endpoint and trigger its deserialization via the second. The deserialization error fires the object destructor, enabling POP-chain RCE.

Detection indicators:

  • Failed to decode session object in response body
  • Session object destruction failed in response body

php2shell Session Injection + LFI Chain

This is the full end-to-end PoC chain:

  1. POST multipart to any PHP endpoint with PHP_SESSION_UPLOAD_PROGRESS and a filename of <?php echo 'MARKER'; ?>
  2. The PHP engine writes the filename into the session file at /tmp/sess_<SID>
  3. GET the LFI endpoint including /tmp/sess_<SID> — PHP executes the code in the filename field
  4. The marker echoes back, confirming full RCE is achievable by replacing echo with system()

Features

  • 4 detection checks in a single script
  • Zero external dependencies — pure Python 3.6+ stdlib
  • Colored terminal output for fast triage
  • JSON output mode for CI/CD integration (--json)
  • Configurable timeout and all paths/endpoints via CLI flags
  • Exit code 1 if any vulnerability is confirmed (pipeline-friendly)
  • Safe — read-only probes, no payloads that persist or cause damage

Installation

No pip install needed:

git clone https://github.com/pentestershell/php2shellbt.git
cd php2shellbt
python3 php2shellbt.py --help

Or download the single file directly:

curl -O https://raw.githubusercontent.com/pentestershell/php2shellbt/main/php2shellbt.py
python3 php2shellbt.py --help

Requirements: Python 3.6 or later, no third-party packages.

Usage

Basic scan (checks 1 + 2 always run)

python3 php2shellbt.py https://target.com

With LFI endpoint (adds check 4 — session injection chain)

python3 php2shellbt.py https://target.com \
  --lfi "/vuln.php?page=" \
  --session-path /tmp/sessions/sess_

With handler-mismatch paths (adds check 3)

python3 php2shellbt.py https://target.com \
  --write-path /upload.php \
  --read-path /api/data.php

Full suite — all 4 checks

python3 php2shellbt.py https://target.com --all \
  --lfi "/vuln.php?page=" \
  --session-path /tmp/sessions/sess_ \
  --write-path /upload.php \
  --read-path /api/data.php

JSON output (for CI/CD or SIEM ingestion)

python3 php2shellbt.py https://target.com --json

Example JSON output:

{
  "target": "https://target.com",
  "results": {
    "cve109619": "VULNERABLE",
    "cve109618": "NOT_FOUND",
    "handler": "SKIPPED",
    "session_lfi": "NOT_FOUND"
  }
}

CLI Reference

Flag Default Description
target (required) Base URL of the target (e.g. https://example.com)
--all Off Run all 4 checks (requires --lfi + --write-path + --read-path)
--lfi PATH — LFI parameter path, e.g. /vuln.php?page=
--session-path PATH /tmp/sessions/sess_ PHP session file prefix on the server
--write-path PATH /app/upload.php Endpoint using session.serialize_handler=php_serialize
--read-path PATH /api/endpoint.php Endpoint using session.serialize_handler=php
--timeout N 10 HTTP request timeout in seconds
--json Off Output results as JSON instead of colored text

Detection Checks Summary

# Check CVE / Type Requires Indicator
1 PHP version fingerprint CVE-2026-109619 Nothing X-Powered-By: PHP/x.y.z in affected range
2 use-after-free / OOM via upload_progress CVE-2026-109618 Nothing Session startup error in response body
3 Handler mismatch deserialization php2shell-mismatch --write-path + --read-path Failed to decode session object
4 Session injection + LFI chain php2shell-lfi --lfi + --session-path Marker echoed back via LFI

Note on check 2: PHP must have display_errors = On for the error indicators to appear in the response body. A "clean" response does not rule out CVE-2026-109618 — it may just be hidden.

Affected Versions

PHP Branch Vulnerable range Fixed version
5.x 5.4.0 – latest 5.x Not patched (EOL) — Sury backported packages (e.g. 5.6.40-104+) may include the fixes; verify the package version
8.2.x 8.2.0 – 8.2.34 8.2.35
8.3.x 8.3.0 – 8.3.35 8.3.36
8.4.x 8.4.0 – 8.4.26 8.4.27
8.5.x 8.5.0 – 8.5.11 8.5.12

Remediation

  1. Upgrade PHP to the fixed version for your branch (8.2.35 / 8.3.36 / 8.4.27 / 8.5.12 or later)
  2. Set session.upload_progress.enabled = Off in php.ini if file upload progress is not needed
  3. Set session.upload_progress.cleanup = On to delete session data immediately after upload
  4. Set session.use_strict_mode = On to reject externally supplied session IDs
  5. Ensure all application endpoints use the same session.serialize_handler
  6. Harden LFI: validate and whitelist all file-inclusion parameters; never include user-controlled paths
  7. Consider adding a WAF rule to block multipart requests with PHP code in filename fields

Nuclei Templates

Nuclei YAML templates that inspired this tool are available at:

https://github.com/Ademking/php2shell-nuclei-templates

To run them directly with Nuclei:

nuclei -u https://target.com -t /path/to/php2shell/

Legal Disclaimer

This tool is intended for authorized security assessments only.

Use of php2shellbt against systems you do not own or do not have explicit written permission to test is illegal and unethical. The author assumes no liability for any misuse or damage caused by this tool. Always obtain proper authorization before running any security scan.

References

License

MIT © 2026 pentestershell (BTshell)