Dalfox Server Mode Vulnerable to Unauthenticated Remote Code Execution via found-action
# GHSA: Unauthenticated Remote Code Execution via found-action in Dalfox Server Mode
Summary
When dalfox is started in REST API server mode (dalfox server), the server binds to 0.0.0.0:6664 by default and requires no API key unless the operator explicitly passes --api-key. Because model.Options — including FoundAction and FoundActionShell — is deserialized directly from attacker-supplied JSON in POST /scan, and because dalfox.Initialize explicitly propagates those two fields into the final scan options without stripping them, any unauthenticated caller who can reach the server port can supply an arbitrary shell command that the dalfox process will execute on the host whenever a scan finding is triggered.
Severity
Critical (CVSS 3.1: 10.0)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- Attack Vector: Network — the server binds to
0.0.0.0 by default; reachable by any network peer. - Attack Complexity: Low — the attacker fully controls the scanned URL and can trivially host a one-line reflective server to guarantee a finding is triggered.
- Privileges Required: None — no API key is enforced in the default configuration.
- User Interaction: None.
- Scope: Changed — exploitation escapes the dalfox process boundary and executes arbitrary commands on the host OS.
- Confidentiality Impact: High — full read access to the host filesystem and secrets in the process environment.
- Integrity Impact: High — arbitrary file writes, code deployment, persistence mechanisms.
- Availability Impact: High — process kill, resource exhaustion, service disruption.
Affected Component
cmd/server.go — init() (line 51): --api-key defaults to ""pkg/server/server.go — setupEchoServer() (line 68): auth middleware only registered when APIKey != ""pkg/server/server.go — postScanHandler() (lines 173–191): rq.Options passed to ScanFromAPI without sanitizationlib/func.go — Initialize() (lines 118–119): FoundAction / FoundActionShell explicitly propagated from caller optionspkg/scanning/foundaction.go — foundAction() (lines 17–18): exec.Command(options.FoundActionShell, "-c", afterCmd) executed unconditionally
CWE
- CWE-306: Missing Authentication for Critical Function
- CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
- CWE-15: External Control of System or Configuration Setting
Description
Opt-in Authentication with a Dangerous Default
cmd/server.go registers the --api-key flag with an empty string default:
```go
// cmd/server.go:51
serverCmd.Flags().StringVar(&apiKey, "api-key", "", "Specify the API key for server authentication...")
```
setupEchoServer only installs the apiKeyAuth middleware when that value is non-empty:
```go
// pkg/server/server.go:68-70
if options.ServerType == "rest" && options.APIKey != "" {
e.Use(apiKeyAuth(options.APIKey, options))
}
```
A server started without --api-key accepts every request on every route with no challenge. The apiKeyAuth implementation itself is correct — the flaw is purely in the opt-in condition that makes authentication off by default.
Attacker-Controlled Options Reaches Shell Execution Without Stripping
POST /scan deserializes the full model.Options struct from the JSON body:
```go
// pkg/server/model.go:6-8
type Req struct {
URL string json:"url"
Options model.Options json:"options"
}
// pkg/server/server.go:173-191
rq := new(Req)
if err := c.Bind(rq); err != nil { ... }
go ScanFromAPI(rq.URL, rq.Options, *options, sid)
```
model.Options exposes both execution-control fields as JSON-tagged properties:
```go
// pkg/model/options.go:83-84
FoundAction string json:"found-action,omitempty"
FoundActionShell string json:"found-action-shell,omitempty"
```
ScanFromAPI builds the scan target directly from rqOptions and passes it to dalfox.Initialize:
```go
// pkg/server/scan.go:22-27
target := dalfox.Target{
URL: url,
Method: rqOptions.Method,
Options: rqOptions,
}
newOptions := dalfox.Initialize(target, target.Options)
```
Initialize explicitly copies both fields into newOptions — there is no stripping path:
```go
// lib/func.go:118-119
"FoundAction": {&newOptions.FoundAction, options.FoundAction},
"FoundActionShell": {&newOptions.FoundActionShell, options.FoundActionShell},
```
Shell Execution on Any Finding
foundAction is called from seven locations across pkg/scanning/scanning.go and pkg/scanning/sendReq.go whenever options.FoundAction != "" and any vulnerability is detected. None of these call sites check options.IsAPI:
```go
// pkg/scanning/foundaction.go:12-18
func foundAction(options model.Options, target, query, ptype string) {
afterCmd := options.FoundAction
afterCmd = string
