Insecure Deserialization in Chi with Cockroachdb

Insecure deserialization occurs when an application processes untrusted data without sufficient validation, allowing attackers to manipulate object graphs during serialization and deserialization. In a Chi-based service that uses CockroachDB as the primary data store, this risk is amplified when session or request data is serialized to store user state, track authentication tokens, or cache query results.

Chi is a lightweight, idiomatic router for building HTTP services in Go. When developers use gob, JSON, or other formats to encode structs representing user sessions or role information — and then store or transmit those encoded values — insecure deserialization can occur if the application trusts the serialized content. CockroachDB, a distributed SQL database compatible with PostgreSQL, is often used to persist this data. If an attacker can supply a malicious serialized payload that the Chi application deserializes and subsequently uses in a database query, they may trigger type confusion, execute unintended code paths, or escalate privileges.

For example, if a Chi handler decodes a base64-encoded gob payload to restore a user session and then uses fields from that session to construct a CockroachDB query without strict type checks, an attacker can inject crafted objects that alter query behavior or bypass authorization checks. The combination of Chi’s flexible routing and CockroachDB’s SQL interface means that deserialization flaws can lead to unauthorized data access or injection-like behaviors even when the database itself does not directly evaluate Go objects.

Additionally, if the application exposes an endpoint that accepts serialized objects from clients — such as importing user preferences or workflow definitions — and persists them to CockroachDB, the deserialization step becomes a critical attack surface. Attackers may attempt to exploit known gadget chains in the Go runtime or leverage database-specific fields to influence how the application later interacts with CockroachDB, potentially leading to data exfiltration or unauthorized modification of records.

To mitigate insecure deserialization in a Chi service that stores data in CockroachDB, adopt strict input validation, avoid deserializing untrusted data, and enforce schema-based data handling. Below are concrete code examples demonstrating secure patterns.

1. Avoid gob for client-supplied data

Do not use Go’s gob encoding to deserialize data that originates from clients. Instead, use JSON with strict schema validation.

// Unsafe: deserializing gob from client input
func unsafeDecode(w http.ResponseWriter, r *http.Request) {
    payload := r.FormValue("data")
    reader := bytes.NewReader(base64.StdEncoding.DecodeString(payload))
    dec := gob.NewDecoder(reader)
    var userData map[string]interface{}
    if err := dec.Decode(&userData); err != nil {
        http.Error(w, "invalid data", http.StatusBadRequest)
        return
    }
    // Risk: userData may contain malicious types
}

// Secure: use JSON with a strict struct
type UserPrefs struct {
    Theme string `json:"theme" validate:"required,printascii"`
    Locale string `json:"locale" validate:"required,alpha"`
}

func secureDecode(c *chi.Mux, db *sql.DB) {
    c.Post("/prefs", func(w http.ResponseWriter, r *http.Request) {
        var prefs UserPrefs
        if err := json.NewDecoder(r.Body).Decode(&prefs); err != nil {
            http.Error(w, "invalid JSON", http.StatusBadRequest)
            return
        }
        // Validate using explicit checks or a library
        if prefs.Theme == "" || prefs.Locale == "" {
            http.Error(w, "missing fields", http.StatusBadRequest)
            return
        }
        // Safe insertion into CockroachDB
        _, err := db.ExecContext(r.Context(), "INSERT INTO user_prefs (user_id, theme, locale) VALUES ($1, $2, $3)", r.Context().Value("userID"), prefs.Theme, prefs.Locale)
        if err != nil {
            http.Error(w, "server error", http.StatusInternalServerError)
            return
        }
        w.WriteHeader(http.StatusCreated)
    })
}

2. Parameterized queries with CockroachDB

Always use parameterized statements when interacting with CockroachDB to prevent injection derived from deserialized data.

// Using database/sql with placeholders
_, err := db.ExecContext(ctx,
    "UPDATE profiles SET settings = $1 WHERE user_id = $2",
    settingsJSON,
    userID,
)
if err != nil {
    // handle error
}

3. Validate and sanitize stored objects

If you must store structured data, serialize only trusted server-generated content and validate on read. Use JSONB columns in CockroachDB and validate fields individually rather than relying on deserialization of opaque blobs.

var result map[string]interface{}
if err := db.QueryRowContext(ctx, "SELECT settings FROM profiles WHERE user_id = $1", userID).Scan(&settingsJSON); err != nil {
    // handle error
}
if err := json.Unmarshal(settingsJSON, &result); err != nil {
    // handle error
}
// Inspect keys and types explicitly
if _, ok := result["prefs"].(map[string]interface{}); !ok {
    // reject malformed data
}