The software does not encrypt sensitive or critical information before storage or transmission.
Extended Description
The lack of proper data encryption passes up the guarantees of confidentiality, integrity, and accountability that properly implemented encryption conveys.
Time of Introduction
Architecture and Design
Operation
Applicable Platforms
Languages
Language-independent
Common Consequences
Scope
Effect
Confidentiality
Technical Impact: Read application
data
If the application does not use a secure channel, such as SSL, to
exchange sensitive information, it is possible for an attacker with
access to the network traffic to sniff packets from the connection and
uncover the data. This attack is not technically difficult, but does
require physical access to some portion of the network over which the
sensitive data travels. This access is usually somewhere near where the
user is connected to the network (such as a colleague on the company
network) but can be anywhere along the path from the user to the end
server.
Confidentiality
Integrity
Technical Impact: Modify application
data
Omitting the use of encryption in any program which transfers data
over a network of any kind should be considered on par with delivering
the data sent to each user on the local networks of both the sender and
receiver. Worse, this omission allows for the injection of data into a
stream of communication between two parties -- with no means for the
victims to separate valid data from invalid. In this day of widespread
network attacks and password collection sniffers, it is an unnecessary
risk to omit encryption from the design of any system which might
benefit from it.
Likelihood of Exploit
High to Very High
Detection Methods
Manual Analysis
The characterizaton of sensitive data often requires domain-specific
understanding, so manual methods are useful. However, manual efforts
might not achieve desired code coverage within limited time constraints.
Black box methods may produce artifacts (e.g. stored data or unencrypted
network transfer) that require manual evaluation.
Effectiveness: High
Automated Analysis
Automated measurement of the entropy of an input/output source may
indicate the use or lack of encryption, but human analysis is still
required to distinguish intentionally-unencrypted data (e.g. metadata)
from sensitive data.
Demonstrative Examples
Example 1
This code writes a user's login information to a cookie so the user
does not have to login again later.
The code stores the user's username and password in plaintext in a cookie on the user's machine. This exposes the user's login information if their computer is compromised by an attacker. Even if the user's machine is not compromised, this weakness combined with cross-site scripting (CWE-79) could allow an attacker to remotely copy the cookie.
Also note this example code also exhibits Plaintext Storage in a Cookie (CWE-315).
Example 2
The following code attempts to establish a connection, read in a
password, then store it to a buffer.
(Bad Code)
Example
Language: C
server.sin_family = AF_INET; hp = gethostbyname(argv[1]);
if (connect(sock, (struct sockaddr *)&server, sizeof
server) < 0) error("Connecting");
...
while ((n=read(sock,buffer,BUFSIZE-1))!=-1) {
write(dfd,password_buffer,n);
...
While successful, the program does not encrypt the data before writing
it to a buffer, possibly exposing it to unauthorized actors.
Example 3
The following code attempts to establish a connection to a site to
communicate sensitive information.
(Bad Code)
Example
Language: Java
try {
URL u = new URL("http://www.secret.example.org/");
HttpURLConnection hu = (HttpURLConnection)
u.openConnection();
hu.setRequestMethod("PUT");
hu.connect();
OutputStream os = hu.getOutputStream();
hu.disconnect();
}
catch (IOException e) {
//...
}
Though a connection is successfully made, the connection is
unencrypted and it is possible that all sensitive data sent to or
received from the server will be read by unintended actors.
Product sends file with cleartext passwords in
e-mail message intended for diagnostic purposes.
Potential Mitigations
Phase: Requirements
Clearly specify which data or resources are valuable enough that they
should be protected by encryption. Require that any transmission or
storage of this data/resource should use well-vetted encryption
algorithms.
Phase: Architecture and Design
Strategy: Threat Modeling
Using threat modeling or other techniques, assume that the data can be compromised through a separate vulnerability or weakness, and determine where encryption will be most effective. Ensure that data that should be private is not being inadvertently exposed using weaknesses such as insecure permissions (CWE-732). [R.311.1]
Phase: Architecture and Design
Ensure that encryption is properly integrated into the system design,
including but not necessarily limited to:
Encryption that is needed to store or transmit private data of the
users of the system
Encryption that is needed to protect the system itself from
unauthorized disclosure or tampering
Identify the separate needs and contexts for encryption:
One-way (i.e., only the user or recipient needs to have the key).
This can be achieved using public key cryptography, or other
techniques in which the encrypting party (i.e., the software) does
not need to have access to a private key.
Two-way (i.e., the encryption can be automatically performed on
behalf of a user, but the key must be available so that the
plaintext can be automatically recoverable by that user). This
requires storage of the private key in a format that is recoverable
only by the user (or perhaps by the operating system) in a way that
cannot be recovered by others.
Phase: Architecture and Design
Strategy: Libraries or Frameworks
When there is a need to store or transmit sensitive data, use strong,
up-to-date cryptographic algorithms to encrypt that data. Select a
well-vetted algorithm that is currently considered to be strong by
experts in the field, and use well-tested implementations. As with all
cryptographic mechanisms, the source code should be available for
analysis.
For example, US government systems require FIPS 140-2
certification.
Do not develop custom or private cryptographic algorithms. They will
likely be exposed to attacks that are well-understood by cryptographers.
Reverse engineering techniques are mature. If the algorithm can be
compromised if attackers find out how it works, then it is especially
weak.
Periodically ensure that the cryptography has not become obsolete. Some older algorithms, once thought to require a billion years of computing time, can now be broken in days or hours. This includes MD4, MD5, SHA1, DES, and other algorithms that were once regarded as strong. [R.311.5]
Phase: Architecture and Design
Strategy: Separation of Privilege
Compartmentalize the system to have "safe" areas where trust
boundaries can be unambiguously drawn. Do not allow sensitive data to go
outside of the trust boundary and always be careful when interfacing
with a compartment outside of the safe area.
Ensure that appropriate compartmentalization is built into the system
design and that the compartmentalization serves to allow for and further
reinforce privilege separation functionality. Architects and designers
should rely on the principle of least privilege to decide when it is
appropriate to use and to drop system privileges.
Phases: Implementation; Architecture and Design
When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.
Phase: Implementation
Strategy: Identify and Reduce Attack Surface
Use naming conventions and strong types to make it easier to spot when
sensitive data is being used. When creating structures, objects, or
other complex entities, separate the sensitive and non-sensitive data as
much as possible.
Effectiveness: Defense in Depth
This makes it easier to spot places in the code where data is being
used that is unencrypted.
Passively Sniff and Capture Application Code Bound for Authorized Client
References
[R.311.1] [REF-11] M. Howard and
D. LeBlanc. "Writing Secure Code". Chapter 9, "Protecting Secret Data" Page
299. 2nd Edition. Microsoft. 2002.
[R.311.2] [REF-17] Michael Howard, David LeBlanc
and John Viega. "24 Deadly Sins of Software Security". "Sin 17: Failure to Protect Stored Data." Page
253. McGraw-Hill. 2010.
[R.311.4] [REF-7] Mark Dowd, John McDonald
and Justin Schuh. "The Art of Software Security Assessment". Chapter 2, "Common Vulnerabilities of Encryption", Page
43.. 1st Edition. Addison Wesley. 2006.
Description
