Standard attack pattern
Draft
CAPEC-20: Encryption Brute Forcing
An attacker, armed with the cipher text and the encryption algorithm used, performs an exhaustive (brute force) search on the key space to determine the key that decrypts the cipher text to obtain the plaintext.
Last updated
Low
Typical severity
Per MITRE
Low
Likelihood of attack
Per MITRE
4
Related weaknesses
CWEs this targets
Standard
Abstraction
MITRE classification
Overview
CAPEC-20 (Encryption Brute Forcing) is a standard-level attack pattern catalogued by MITRE in the Common Attack Pattern Enumeration and Classification (CAPEC). It describes a recurring method attackers use to exploit software weaknesses.
How the attack works
The phases an attacker typically follows to carry out this attack.
- Step 1Explore
Determine the ciphertext and the encryption algorithm.
- Step 2Experiment
Perform an exhaustive brute force search of the key space, producing candidate plaintexts and observing if they make sense.
What the attacker needs
Prerequisites
- Ciphertext is known.
- Encryption algorithm and key size are known.
Skills required
- Low skill: Brute forcing encryption does not require much skill.
Resources required
- A powerful enough computer for the job with sufficient CPU, RAM and HD. Exact requirements will depend on the size of the brute force job and the time requirement for completion. Some brute forcing jobs may require grid or distributed computing (e.g. DES Challenge). On average, for a binary key of size N, 2^(N/2) trials will be needed to find the key that would decrypt the ciphertext to obtain the original plaintext. Obviously as N gets large the brute force approach becomes infeasible.