Nextcloud 10.0 privilege escalation issue - Normal user can mask external storage shared by admin
Medium
N
Nextcloud
Submitted None
Actions:
Reported by
egrep
Vulnerability Details
Technical details and impact analysis
Normal user(Non-privileged) can mask external storage shared by admin.
Scenario :
Created three users "admin", "attacker", "victim"
Created group "samplegroup" containing all the three users with "victim" as group admin
Steps:
1) User "admin" created external storage named "localstrg"(note: name is the attack vector) with properties:
Folder Name : localstrg
External Storage : Local
Authentication : None
Configuration : /
Available for : "samplegroup","admin" - groups
Settings : Enable sharing
2) On seeing this , user "attacker" created one more external storage with the same name "localstrg" with properties:
Folder Name : localstrg
External Storage : SFTP
Authentication : Username and Password
Configuration : Fill "Host", "Root" ," Username" ,"Password"
Settings : Enable sharing
3) After that, user "attacker" shared created external storage with group "samplegroup" which is having other two users
4) If suppose, user "victim" visits the external storage "localstrg" in his profile, he is only shown with files shared by user "attacker"
Prerequisite : Both attacker and victim should be in the same group
Using this vulnerability, non-privilged user can mask the external storage shared by admin to other users
Report Details
Additional information and metadata
State
Closed
Substate
Resolved
Submitted
Weakness
Privilege Escalation