CWE-323: Reusing a Nonce, Key Pair in Encryption Reusing a Nonce, Key Pair in Encryption
Weakness ID: 323 (Weakness Base) Status: Incomplete
Description
Description Summary
Nonces should be used for the present occasion and only once.
Time of Introduction
Common Consequences
Scope Effect Access Control
Technical Impact: Bypass protection
mechanism; Gain privileges / assume
identity
Potentially a replay attack, in which an attacker could send the same
data twice, could be crafted if nonces are allowed to be reused. This
could allow a user to send a message which masquerades as a valid
message from a valid user.
Likelihood of Exploit
Demonstrative Examples
Example 1
(Bad Code)
Example
Language: C
#include <openssl/sha.h>
#include <stdio.h>
#include <string.h>
#include <memory.h>
int main(){
char *paragraph = NULL;
char *data = NULL;
char *nonce = "bad";
char *password = "secret";
parsize=strlen(nonce)+strlen(password);
paragraph=(char*)malloc(para_size);
strncpy(paragraph,nonce,strlen(nonce));
strcpy(paragraph,password,strlen(password));
data=(unsigned char*)malloc(20);
SHA1((const unsigned char*)paragraph,parsize,(unsigned
char*)data);
free(paragraph);
free(data);
//Do something with data//
return 0;
}
(Bad Code)
Example
Language: C++
String command = new String("some command to execute");
MessageDigest nonce = MessageDigest.getInstance("SHA");
nonce.update(String.valueOf("bad nonce"));
byte[] nonce = nonce.digest();
MessageDigest password = MessageDigest.getInstance("SHA");
password.update(nonce + "secretPassword");
byte[] digest = password.digest();
//do something with digest//
Potential Mitigations
Requirements specification: The choice could be made to use a language
that is not susceptible to these issues.
Phase: Implementation
Refuse to reuse nonce values.
Phase: Implementation
Use techniques such as requiring incrementing, time based and/or
challenge response to assure uniqueness of nonces.
Background Details
Nonces are often bundled with a key in a communication exchange to produce
a new session key for each exchange.
Relationships
Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name CLASP Reusing a nonce, key pair in encryption
Content History
Submissions Submission Date Submitter Organization Source CLASP Externally Mined Modifications Modification Date Modifier Organization Source 2008-07-01 Eric Dalci Cigital External updated Time_of_Introduction 2008-09-08 CWE Content Team MITRE Internal updated Background_Details, Common_Consequences,
Relationships, Taxonomy_Mappings 2011-06-01 CWE Content Team MITRE Internal updated Common_Consequences
Description
