GHSA-4mf2-f3wh-gvf2

Опубликовано: 25 мая 2021

Источник: github

Github: Прошло ревью

CVSS3: 5.4

Описание

Subdomain checking of whitelisted domains could allow unintended redirects in oauth2-proxy

Impact

What kind of vulnerability is it? Who is impacted? For users that use the whitelist domain feature, a domain that ended in a similar way to the intended domain could have been allowed as a redirect.

For example, if a whitelist domain was configured for .example.com, the intention is that subdomains of example.com are allowed. Instead, example.com and badexample.com could also match.

Patches

Has the problem been patched? What versions should users upgrade to? This is fixed in version 7.0.0 onwards.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading? Disable the whitelist domain feature and run separate OAuth2 Proxy instances for each subdomain.

Original Issue Posted by @semoac:

Whitelist Domain feature is not working as expected because is not matching a dot to ensure the redirect is a subdomain.

Expected Behavior

If whitelist domain is set to .example.com , then hack.alienexample.com should be rejected as a valid redirect.

Current Behavior

The code is removing the dot from .example.com and only checking if the redirect string end with example.com

Possible Solution

Here https://github.com/oauth2-proxy/oauth2-proxy/blob/c377466411f2aee180a732187edb638f2f7e57fb/oauthproxy.go#L661

Include the dot when checking the string:

strings.HasSuffix(redirectHostname, "." + domainHostname)

Steps to Reproduce (for bugs)

package main import ( "fmt" "strings" ) func validOptionalPort(port string) bool { if port == "" || port == ":*" { return true } if port[0] != ':' { return false } for _, b := range port[1:] { if b < '0' || b > '9' { return false } } return true } func splitHostPort(hostport string) (host, port string) { host = hostport colon := strings.LastIndexByte(host, ':') if colon != -1 && validOptionalPort(host[colon:]) { host, port = host[:colon], host[colon+1:] } if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") { host = host[1 : len(host)-1] } return } func main() { domain := ".example.com" domainHostname, _ := splitHostPort(strings.TrimLeft(domain, ".")) redirectHostname := "https://hack.alienexample.com" if (strings.HasPrefix(domain, ".") && strings.HasSuffix(redirectHostname, domainHostname)) { fmt.Println("This should not have happen.")} }

Users of github.com/oauth2-proxy/oauth2-proxy are advised to update to github.com/oauth2-proxy/oauth2-proxy/v7

Ссылки

Пакеты

Наименование

github.com/oauth2-proxy/oauth2-proxy/v7

Затронутые версииВерсия исправления

< 7.0.0

7.0.0

Наименование

github.com/oauth2-proxy/oauth2-proxy

Затронутые версииВерсия исправления

<= 3.2.0

Отсутствует

EPSS

Процентиль: 47%

0.0024

Низкий

5.4 Medium

CVSS3

CVE ID

CVE-2021-21291

Дефекты

CWE-601

Связанные уязвимости

CVE-2021-21291

CVSS3: 4.7

nvd

около 5 лет назад

OAuth2 Proxy is an open-source reverse proxy and static file server that provides authentication using Providers (Google, GitHub, and others) to validate accounts by email, domain or group. In OAuth2 Proxy before version 7.0.0, for users that use the whitelist domain feature, a domain that ended in a similar way to the intended domain could have been allowed as a redirect. For example, if a whitelist domain was configured for ".example.com", the intention is that subdomains of example.com are allowed. Instead, "example.com" and "badexample.com" could also match. This is fixed in version 7.0.0 onwards. As a workaround, one can disable the whitelist domain feature and run separate OAuth2 Proxy instances for each subdomain.

CVE-2021-21291

CVSS3: 4.7

debian

около 5 лет назад

OAuth2 Proxy is an open-source reverse proxy and static file server th ...

EPSS

Процентиль: 47%

0.0024

Низкий

5.4 Medium

CVSS3

CVE ID

CVE-2021-21291

Дефекты

CWE-601