diff --git a/problem-sets-competitive-programming.md b/problem-sets-competitive-programming.md
index 2a3e19ade780392a5e1cb834be2c8af9d9d16a6e..232773746428249db0258096c0a939995bf253c6 100644
--- a/problem-sets-competitive-programming.md
+++ b/problem-sets-competitive-programming.md
@@ -2,6 +2,7 @@
 
 * [Competitive Programming](#competitive-programming)
 * [Data science](#data-science)
+* [Information security](#information-security)
 * [Problem Sets](#problem-sets)
 
 
@@ -36,6 +37,11 @@
 * [Kaggle](https://www.kaggle.com)
 
 
+### Information security
+
+* [CTFtime](https://ctftime.org)
+
+
 ### Problem Sets
 
 * [500 Data structures and algorithms interview questions and their solutions in C++](https://techiedelight.quora.com/500-Data-structures-and-algorithms-interview-questions-and-their-solutions-in-C%2B%2B)