[Openstack-security] Hmac keys in Swift tempurl middleware

Alexandra Shulman-Peleg SHULMANA at il.ibm.com
Wed Aug 28 10:30:23 UTC 2013


Hi,

In tempurl middleware of Swift there is an hmac signature calculated with 
keys stored in account meta data attributes temp-url-key', 
'temp-url-key-2' (see the function get_tempurl_keys_from_metadata in 
swift/common/middleware/tempurl.py). 

The generated signature allows access to the resources with URLs like 
https://swift-cluster.example.com/v1/AUTH_account/container/object?temp_url_sig=da39a3ee5e6b4b0d3255bfef95601890afd80709&temp_url_expires=1323479485
.  
 
It seems that keeping the keys un-encrypted as part of the account info is 
a security vulnerability which allows anyone who can read the account meta 
data to generate and fake temp urls. Shouldn't we protect the keys used to 
calculate the hmac, either through encryption or by limiting their 
visibility? 

Best Regards,
Alex. 

----------------------------------------------------------
Alexandra Shulman-Peleg, PhD
Storage Research, Cloud Platforms 
IBM Haifa Research Lab
Tel: +972-3-7689530 | Fax: +972-3-7689545
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