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GHSA-fgxv-gw55-r5fq
No affected components available
Summary
Hello go-zero maintainer team, I would like to report a security concerning your CORS Filter feature.
Details
Go-zero allows user to specify a CORS Filter with a configurable allows param - which is an array of domains allowed in CORS policy.
However, the isOriginAllowed uses strings.HasSuffix to check the origin, which leads to bypass via domain like evil-victim.com
func isOriginAllowed(allows []string, origin string) bool {
for _, o := range allows {
if o == allOrigins {
return true
}
if strings.HasSuffix(origin, o) {
return true
}
}
return false
}
PoC
Use code below as a PoC. Only requests from safe.com should bypass the CORS Filter
package main
import (
"errors"
"net/http"
"github.com/zeromicro/go-zero/rest"
)
func main() {
svr := rest.MustNewServer(rest.RestConf{Port: 8888}, rest.WithRouter(mockedRouter{}), rest.WithCors("safe.com"))
svr.Start()
}
type mockedRouter struct{}
// some sensitive path
func (m mockedRouter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// check user's cookie
// ...
// return sensitive data
w.Write([]byte("social_id: 420101198008292930"))
}
func (m mockedRouter) Handle(_, _ string, handler http.Handler) error {
return errors.New("foo")
}
func (m mockedRouter) SetNotFoundHandler(_ http.Handler) {
}
func (m mockedRouter) SetNotAllowedHandler(_ http.Handler) {
}
Send a request to localhost:8888 with Origin:not-safe.com
You can see the origin reflected in response, which bypass the CORS Filter
Impact
This vulnerability is capable of breaking CORS policy and thus allowing any page to make requests, retrieve data on behalf of other users.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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