Figure 6: Changes in attack vector over the years
Account
Access
Broken
Signature System
Default
Password Exploit
Pre-
signature Insertion
Self-signed/Unsigned
Stolen/Purchased
Certificate
Unknown,
Other, or N/A
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
2010
1
0
0
0
1
1
0
2011
2
0
1
0
1
0
0
2012
1
0
0
0
0
0
0
2013
1
0
0
1
0
1
4
2014
1
0
0
0
0
0
4
2015
1
1
2
4
1
1
6
2016
1
0
0
1
4
0
1
2017
3
1
1
4
7
0
2
2018
1
3
0
3
7
5
9
2019
3
2
2
4
6
1
8
2020
0
0
1
2
6
2
4
