Injection Flaws in Echo Go with Cockroachdb

Injection flaws occur when untrusted data is sent to an interpreter as part of a command or query. In the combination of Echo Go and Cockroachdb, this typically manifests as SQL injection when constructing database queries by concatenating user input into SQL strings. Because Cockroachdb speaks the PostgreSQL wire protocol, common PostgreSQL patterns and placeholders apply, but Go code that does not use prepared statements or query builders remains vulnerable.

Echo is a lightweight HTTP router and middleware framework. When handlers build SQL strings dynamically—for example, filtering or sorting by user-supplied query parameters—they may embed values directly into the query. Consider a handler that reads a user_id from the request and builds a statement like "SELECT * FROM users WHERE id = '" + userID + "'". If userID contains SQL meta-characters or crafted syntax, an attacker can alter the intent of the query, bypass authentication, or read/modify other rows. This becomes particularly risky because Cockroachdb supports multiple SQL statements in some drivers if not properly parameterized, potentially enabling stacked queries.

Cockroachdb-specific behaviors can amplify the impact. For instance, Cockroachdb’s support for PostgreSQL-style placeholders (e.g., $1, $2) means that using database/sql prepared statements with db.Query or db.Exec correctly protects against injection. However, if developers use string formatting to construct the placeholder names themselves (dynamic SQL object names), or use ORM methods that concatenate table/column names, the protection is bypassed. Additionally, Cockroachdb’s JSONB operators and array expressions allow nested data access; injecting into keys or paths used in jsonb_extract_path_text or similar constructs can expose sensitive nested fields or enable privilege escalation via crafted data extraction.

Another vector specific to Echo is middleware that modifies request context and passes it to handlers. If a middleware component attaches user-controlled values to the context and a downstream handler uses those values to build queries without sanitization, injection can occur indirectly. For example, a tracing ID or tenant slug placed in the context and then interpolated into a Cockroachdb SQL string can enable tenant isolation bypass or information disclosure across tenants.

To illustrate, an insecure Echo handler might look like this, demonstrating the vulnerability directly:

package main

import (
    "database/sql"
    "github.com/labstack/echo/v4"
    _ "github.com/jackc/pgx/v5/stdlib"
    "net/http"
)

func unsafeHandler(c echo.Context) error {
    db, _ := sql.Open("pgx", "postgresql://user:pass@localhost:26257/mydb?sslmode=disable")
    userID := c.QueryParam("user_id")
    query := "SELECT email, role FROM users WHERE id = '" + userID + "'"
    var email, role string
    if err := db.QueryRow(query).Scan(&email, &role); err != nil {
        return err
    }
    return c.JSON(http.StatusOK, map[string]string{"email": email, "role": role})
}

func main() {
    e := echo.New()
    e.GET("/profile", unsafeHandler)
    e.Start(":8080")
}

In this example, an attacker could supply user_id=1' OR '1'='1 to authenticate as any user, or use stacked queries if supported to extract data from other tables. The fix is to always use parameterized queries with placeholders, ensuring input is treated strictly as data.

Remediation centers on using parameterized queries and avoiding string interpolation for SQL commands. With Cockroachdb and Go, always use db.Query, db.Exec, or db.QueryRow with placeholders ($1, $2) rather than injecting values into the SQL string. For dynamic identifiers such as table or column names, which cannot be parameterized, use strict allow-listing and validate against a known set of values before constructing the query.

Here is a secure version of the previous handler using placeholders:

package main

import (
    "database/sql"
    "github.com/labstack/echo/v4"
    _ "github.com/jackc/pgx/v5/stdlib"
    "net/http"
)

func safeHandler(c echo.Context) error {
    db, _ := sql.Open("pgx", "postgresql://user:pass@localhost:26257/mydb?sslmode=disable")
    userID := c.QueryParam("user_id")
    var email, role string
    // Use a placeholder to separate SQL logic from data
    err := db.QueryRow(c.Request().Context(), "SELECT email, role FROM users WHERE id = $1", userID).Scan(&email, &role)
    if err != nil {
        return err
    }
    return c.JSON(http.StatusOK, map[string]string{"email": email, "role": role})
}

func main() {
    e := echo.New()
    e.GET("/profile", safeHandler)
    e.Start(":8080")
}

For dynamic table or column names, validate against an allow-list:

package main

import (
    "database/sql"
    "fmt"
    "github.com/labstack/echo/v4"
    _ "github.com/jackc/pgx/v5/stdlib"
    "net/http"
    "strings"
)

func columnsHandler(c echo.Context) error {
    db, _ := sql.Open("pgx", "postgresql://user:pass@localhost:26257/mydb?sslmode=disable")
    requestedColumn := c.QueryParam("column")
    allowed := map[string]bool{"name": true, "email": true, "created_at": true}
    if !allowed[requestedColumn] {
        return c.String(http.StatusBadRequest, "invalid column")
    }
    // Safe: column name is validated, value uses placeholder
    query := fmt.Sprintf("SELECT id, %s FROM users WHERE tenant_id = $1", requestedColumn)
    tenantID := c.QueryParam("tenant_id")
    rows, err := db.Query(c.Request().Context(), query, tenantID)
    if err != nil {
        return err
    }
    defer rows.Close()
    // process rows...
    return c.JSON(http.StatusOK, map[string]interface{}{"status": "ok"})
}

When working with JSONB fields, avoid injecting user input into key paths. Instead, use predefined paths or strict validation:

package main

import (
    "database/sql"
    "github.com/jackc/pgx/v5/pgtype"
    "github.com/labstack/echo/v4"
    _ "github.com/jackc/pgx/v5/stdlib"
    "net/http"
)

func jsonHandler(c echo.Context) error {
    db, _ := sql.Open("pgx", "postgresql://user:pass@localhost:26257/mydb?sslmode=disable")
    // Use a fixed path; do not interpolate user input into the path
    var data map[string]interface{}
    err := db.QueryRow(c.Request().Context(), "SELECT data::jsonb FROM profiles WHERE id = $1", c.Param("id")).Scan(pgtype.JSONB{
        Bytes:  []byte{}, // simplified
        Status: pgtype.Present,
    })
    if err != nil {
        return err
    }
    return c.JSON(http.StatusOK, data)
}

These patterns ensure that user input never alters SQL structure or object names, effectively mitigating injection risks for Echo Go applications using Cockroachdb.