| 1 |
W. Trevor King: |
| 2 |
> On Sun, Sep 14, 2014 at 10:38:41PM +0000, hasufell wrote: |
| 3 |
>> Yes, there is a possible attack vector mentioned in this comment |
| 4 |
>> https://bugs.gentoo.org/show_bug.cgi?id=502060#c16 |
| 5 |
> |
| 6 |
> From that comment, the point 1.2 is highly unlikely [1]: |
| 7 |
> |
| 8 |
> 1. Attacker constructs a init.d script, regular part at the start, |
| 9 |
> malicious part at the end |
| 10 |
> 1.1. This would be fairly simple, just construct two start() |
| 11 |
> functions, one of which is mundane, the other is malicious. |
| 12 |
> 1.2. Both variants of the script have the same SHA1... |
| 13 |
> |
| 14 |
>> So we'd basically end up using either "git cherry-pick" or "git am" |
| 15 |
>> for "pulling" user stuff, so that we also sign the blobs. |
| 16 |
> |
| 17 |
> Rebasing the original commits doesn't protect you from the birthday |
| 18 |
> attach either, because the vulnerable hash is likely going to still be |
| 19 |
> in the rebased commit's tree. All rebasing does is swap the committer |
| 20 |
> and drop the initial signature. |
| 21 |
> |
| 22 |
|
| 23 |
According to Robin, it's not about rebasing, it's about signing all |
| 24 |
commits so that messing with the blob (even if it has the same sha-1) |
| 25 |
will cause signature verification failure. |
Archives