Crlf Injection in Buffalo with Cockroachdb

Crlf Injection occurs when an attacker can inject a CRLF sequence (\r\n) into a header or query parameter, causing the application to split or smuggled headers. In a Buffalo application interacting with Cockroachdb, this typically arises when user-controlled input is reflected into HTTP response headers or used to construct database identifiers and query parameters that later influence logging, redirection, or header generation. Buffalo’s parameter parsing and header manipulation features can inadvertently pass attacker-controlled strings to response writers or database drivers, enabling header injection or response splitting when the values are not sanitized.

For example, a route that builds a redirect URL using user input and then queries Cockroachdb for a target resource can become vulnerable if the input is not validated. Consider a handler that takes an id parameter, appends it to a redirect path, and uses it in a SQL WHERE clause:

// routes.go
func MyResource(c buffalo.Context) error {
    id := c.Param("id")
    // Unsafe: id used directly in redirect and SQL
    redirectTo := "/items/" + id
    if err := c.Response().Header().Set("X-Redirect-To", redirectTo); err != nil {
        return c.Error(500, err)
    }
    var item Item
    if err := db.Raw("SELECT * FROM items WHERE id = ?", id).Scan(&item).Error; err != nil {
        return c.Error(500, err)
    }
    return c.Render(200, r.H{"item": item})
}

If id contains %0d%0aSet-Cookie: malicious=1 (URL-decoded to \r\nSet-Cookie: malicious=1), and the framework or underlying driver does not sanitize the header value before setting it, the injected CRLF can split the header and inject a new Set-Cookie header. Even if the database driver itself does not directly reflect the value into headers, the application layer’s use of the tainted id for constructing redirect locations or log entries can facilitate HTTP response splitting or header smuggling when responses are processed by proxies or load balancers. Cockroachdb logs or diagnostic outputs that include raw query strings or identifiers may further expose injected sequences to downstream log parsers that treat CRLF as a line delimiter, enabling log injection or log forging attacks.

The interaction with Cockroachdb becomes relevant in two ways: (1) if application-generated headers include SQL fragments or identifiers that contain CRLF, and (2) if error messages returned by Cockroachdb are reflected into HTTP responses without sanitization. For instance, a malformed query that includes injected CRLF in a string literal may produce database-level errors that echo the tainted input. If those errors are surfaced to the client (e.g., in development mode) or logged verbatim, the injected sequences can propagate through observability pipelines, compounding the injection surface beyond just HTTP headers.

Remediation focuses on strict input validation, output encoding, and separation of data from control headers. Never concatenate user input into header values or SQL identifiers. Use parameterized queries for data, and treat all inputs as untrusted strings when building non-data parts of requests (e.g., URLs, headers).

For redirects and header-sensitive operations, explicitly validate and sanitize the input. Use a whitelist approach for identifiers and enforce a strict pattern (e.g., alphanumeric and underscores only). Avoid setting headers with raw user input. If you must include user data in a header value, percent-encode or base64-encode it, and decode on the recipient side.

Below are concrete Buffalo + Cockroachdb code examples demonstrating secure handling.

Secure Redirect and Parameter Handling

Validate the id before using it in a redirect or header. Use a regex to allow only safe characters, and construct the redirect location without injecting raw input into header fields.

// routes.go
import (
    "github.com/gobuffalo/buffalo"
    "github.com/gobuffalo/buffalo/middleware"
    "regexp"
)

var safeID = regexp.MustCompile(`^[A-Za-z0-9\-_]+$`)

func SecureResource(c buffalo.Context) error {
    id := c.Param("id")
    if !safeID.MatchString(id) {
        return c.Error(400, fmt.Errorf("invalid identifier"))
    }
    // Safe: id is validated; redirect target is built from a controlled path
    redirectTo := "/items/" + id
    // Avoid setting raw user input in headers; if needed, encode it
    encoded := middleware.Base64Encode([]byte(redirectTo))
    if err := c.Response().Header().Set("X-Redirect-To", encoded); err != nil {
        return c.Error(500, err)
    }
    // Use parameterized query for data access
    var item Item
    if err := db.Raw("SELECT * FROM items WHERE id = ?", id).Scan(&item).Error; err != nil {
        return c.Error(500, err)
    }
    return c.Render(200, r.H{"item": item})
}

When interacting with Cockroachdb, always use placeholders for values and avoid interpolating user input into SQL strings. For schema identifiers (e.g., table names), use a strict allowlist and map them server-side.

// dbutils.go
import (
    "github.com/gobuffalo/pop/v6"
    "fmt"
)

// AllowedTables is a server-side allowlist for table names
var AllowedTables = map[string]bool{
    "users": true,
    "items": true,
    "logs":  true,
}

func QueryTable(tx *pop.Connection, table, id string) (interface{}, error) {
    if !AllowedTables[table] {
        return nil, fmt.Errorf("table not allowed")
    }
    // Safe: table name from allowlist, id as parameter
    query := fmt.Sprintf("SELECT * FROM %s WHERE id = $1", table)
    var result interface{}
    if err := tx.RawQuery(query, id).All(&result); err != nil {
        return nil, err
    }
    return result, nil
}

For logging and diagnostics, ensure that any output including user input is sanitized before being written to logs or error responses. Do not rely on Cockroachdb’s error messages to be safe; treat them as potentially containing injected sequences and filter them before exposure.

// logutil.go
import (
    "strings"
)

func SanitizeLogInput(input string) string {
    // Remove or replace CRLF to prevent log injection
    return strings.ReplaceAll(strings.ReplaceAll(input, "\r", "\\r"), "\n", "\\n")
}

func LogQuery(table, id string) {
    safeID := SanitizeLogInput(id)
    safeTable := SanitizeLogInput(table)
    // Proceed with logging using safe representations
    _ = fmt.Sprintf("query table=%s id=%s", safeTable, safeID)
}