Sql Injection Union in Buffalo (Go)

SQL Injection (SQLi) with UNION-based techniques can occur in Buffalo applications written in Go when dynamic query construction is used without proper input validation or parameterized statements. Buffalo is an MVC web framework for Go that encourages convention-based routing and controller actions. If user-controlled input such as query parameters or form values are directly concatenated into SQL strings passed to models.RawQuery or similar data access patterns, an attacker can inject a UNION SELECT payload to read from unrelated tables.

For example, consider a search endpoint that builds a query using string formatting:

query := fmt.Sprintf("SELECT id, name, email FROM users WHERE name LIKE '%%%s%%'", userInput)

If userInput is supplied by an attacker as "admin" UNION SELECT id, password, email FROM admins--", the resulting query combines the original SELECT with an additional SELECT from the admins table. Because Buffalo does not automatically parameterize raw queries, this injection is possible when developers bypass the ORM or use plain SQL. The presence of UNION allows the attacker to align column counts and extract data from tables the application normally does not access, leading to data exposure. This pattern maps to the OWASP API Top 10 A03:2023 Injection and can be detected by middleBrick during black-box scanning of the unauthenticated attack surface.

In the context of middleBrick’s 12 security checks, SQL Injection is surfaced under Input Validation and Property Authorization testing. The scanner does not exploit or modify data; it identifies endpoints where UNION-based SQLi patterns are detectable and provides remediation guidance. Because Buffalo does not enforce query parameterization by default, developers must explicitly use prepared statements or the framework’s query building helpers to avoid these issues.

Remediation in Buffalo centers on using parameterized queries and avoiding string concatenation for SQL. Buffalo integrates with the pop ORM, which supports prepared statements when used correctly. Below are concrete, working examples showing vulnerable code and the secure alternative.

Vulnerable pattern

Using fmt.Sprintf to build raw SQL:

func (v UsersController) Search(c buffalo.Context) error {
    name := c.Param("name")
    query := fmt.Sprintf("SELECT id, name, email FROM users WHERE name LIKE '%%%s%%'", name)
    var users []User
    if err := models.RawQuery(query).All(&users); err != nil {
        return c.Render(500, r.JSON(err))
    }
    return c.Render(200, r.JSON(users))
}

An attacker can supply name=admin' UNION SELECT id, password, email FROM admins-- to extract sensitive columns.

Secure remediation using pop and named arguments

Use pop’s query building with placeholders:

func (v UsersController) Search(c buffalo.Context) error {
    name := c.Param("name")
    var users []User
    q := pop.Select("id, name, email").From("users").Where("name LIKE ?", "%"+name+"%")
    if err := q.All(c, &users); err != nil {
        return c.Render(500, r.JSON(err))
    }
    return c.Render(200, r.JSON(users))
}

In this version, the ? placeholder ensures the input is treated as a value, not executable SQL. The LIKE pattern is constructed safely in Go before being bound to the query.

Alternative: explicit prepared statement with sqlx

If using lower-level sqlx within a Buffalo action, prefer Rebind and named arguments:

func (v UsersController) Search(c buffalo.Context) error {
    name := c.Param("name")
    tx := c.Value("tx").(*pop.Connection)
    query, args, err := sqlx.Named("SELECT id, name, email FROM users WHERE name LIKE :pattern", map[string]interface{}{
        "pattern": "%" + name + "%",
    })
    if err != nil {
        return c.Render(500, r.JSON(err))
    }
    query = tx.Rebind(query)
    var users []User
    if err := tx.Select(&users, query, args...); err != nil {
        return c.Render(500, r.JSON(err))
    }
    return c.Render(200, r.JSON(users))
}

This approach separates SQL structure from data, preventing UNION-based injection. middleBrick’s scans will flag the vulnerable endpoint and reference these remediation steps under the Input Validation and Property Authorization findings.

These fixes align with the framework’s conventions while closing the injection vector. Developers should also validate and sanitize inputs, but parameterization is the primary defense against SQL Injection in Buffalo applications.