kern/188429: MITM attacks against freebsd-update

[David Noel]

>Number:         188429
>Category:       kern
>Synopsis:       MITM attacks against freebsd-update
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Apr 10 16:30:00 UTC 2014
>Closed-Date:
>Last-Modified:
>Originator:     David Noel
>Release:        9.2
>Organization:
>Environment:
>Description:
freebsd-update.sh extracts fetched data prior to its SHA256 verification. The extraction libraries used have a long history of bugs so it’s reasonable to assume there might be more. freebsd-update runs as root. Using a vulnerability in the decompression libraries an attacker who was MITM-capable could compromise any FreeBSD system running freebsd-update.
>How-To-Repeat:

>Fix:
Solution Summary: a re-working of the snapshot hashing and hash verification process.

The functions of concern in freebsd-update.sh are fetch_metadata(), fetch_files_premerge(), and fetch_files().

>Release-Note:
>Audit-Trail:
>Unformatted: