CogniCrypt_SAST

This repository contains CogniCrypt_SAST, the static analysis component for CogniCrypt. The static analysis CogniCrypt_SAST takes rules written in the specification language CrySL as input, and performs a static analysis based on the specification of the rules. CrySL is a domain-specific language (DSL) designed to encode usage specifications for cryptographic libaries (e.g., the JCA in particular). More information on CrySL and the static analysis may be found in this paper.

Releases

You can checkout a pre-compiled version of CogniCrypt_SAST here.

Download the two files:

• CryptoAnalysis-x.y.z-jar-with-dependencies.jar
• JCA-CrySL-rules.zip

Checkout and Build

CogniCrypt_SAST uses Maven as build tool. You can compile and build this project via

mvn package -DskipTests=true.

A packaged jar artifact including all dependency is found in CryptoAnalysis/build/CryptoAnalysis-x.y.z-jar-with-dependencies.jar

Usage

CogniCrypt_SAST can be started in headless mode (i.e., detached from Eclipse) via the class crypto.HeadlessCryptoScanner. It requires two arguments:

• The absolute path to the directory of the CrySL (source code format) rule files. The source code for the rules which contains spesification for the JCA is found here.
• The absolute path of the application to be analyzed (.jar file or the root compilation output folder which contains the .class files in subdirectories)

java -cp <path-to-analysis-jar> crypto.HeadlessCryptoScanner --rulesDir=<absolute-path-to-crysl-source-code-format-rules> \
      --applicationCp=<absolute-application-path>

For an easy start we prepared a .jar containing classes with crypto misuses. The source code for these misuses is found here. To run CogniCrypt_SAST on these classes, simply execute the following command (on a linux based system).

java -cp CryptoAnalysis/build/CryptoAnalysis-2.6-jar-with-dependencies.jar crypto.HeadlessCryptoScanner \
  --rulesDir=$(pwd)/CryptoAnalysis/src/main/resources/JavaCryptographicArchitecture \
  --applicationCp=$(pwd)/CryptoAnalysisTargets/CogniCryptDemoExample/Examples.jar

Note, depending on the analyzed application, the analysis may require a lot of memory and a large stack size. Remember to set the necessary heap size (e.g. -Xmx8g) and stack size (e.g. -Xss60m).

Report and Error Types

In the standard option, CogniCrypt_SAST outputs a report to the console. CogniCrypt_SAST reporst misuses when the code is not compliant with the CrySL rules. For each misuse CogniCrypt_SAST reports the class and the method the misuse is contained in. There are multiple misuse types:

• ConstraintError: A constraint of a CrySL rule is violated, e.g., a key is generated with the wrong key size.

• NeverTypeOfError: Reported when a value was found to be of a certain reference type: For example, a character array containing a password should never be converted from a String. (see KeyStore rule here).

• ForbiddenMethodError: A method that is forbidden (CrySL block FORBIDDEN) to be called under some circumstances was found.

• ImpreciseValueExtractionError: The static analysis was not able to extract all information required within the CrySL CONSTRAINT block. For example the key size could be supplied as a value listed in a configuration file. The static analysis does not model the file's content and may not constraint on the value.

• TypestateError: The ORDER block of CrySL is violated, i.e., the expected method sequence call to be made is incorrect. For example, a Signature object expects a call to initSign(key) prior to update(data).

• RequiredPredicateError: An object A expects an object B to have been used correctly (CrySL blocks REQUIRES and ENSURES). For example a Cipher object requires a SecretKey object to be correctly and securely generated.

• IncompleteOperationError: The usage of an object may be incomplete: For example a Cipherobject may be initialized but never used for en- or decryption, this may render the code dead. This error heavily depends on the computed call graph (CHA by default).

When the option --reportDir=<folder> is chosen, CogniCrypt_SAST writes the report to the file CogniCrypt-Report.txt and additionally outputs the .jimple files of the classes where misuses where found in. Jimple is an intermediate representation close to the syntax of Java.

Updating CrySL Rules

The tool takes CrySL rules in their source code formats (crysl). You can adapt the rules in any text editor. Additionaly, the Eclipse plugin CogniCrypt ships with a CrySL editor to modify the rules with IDE support (e.g., content assist, auto completion, etc.). A step-by-step-explanation on how edit CrySL rules is avialable at the tool's website cognicrypt.org.

CogniCrypt_SAST for Android Applications

CogniCrypt_SAST can also be run on Android Applications using the Android version for CogniCrypt_SAST in CryptoAnalysis-Android. Its usage does not deviate much from regular CogniCrypt_SAST's. CogniCrypt_SAST for Android can be started via the class de.fraunhofer.iem.crypto.CogniCryptAndroid. It requires three arguments in this order:

• The absolute path to the .apk file
• The absolute path to the android SDK platforms. The platforms are obtainable via Android Studio. Under the Android SDK location you find a folder platforms. Supply CogniCrypt_SAST with the path to this folder.
• The absolute path to the directory of the CrySL rules.

java -cp <path-to-analysis-jar> -Xmx8g -Xss60m de.fraunhofer.iem.crypto.CogniCryptAndroid \
      <path-to-apk> <path-to-android-platforms> <path-to-crysl-rules>

As an optional fourth parameter one can specify an output folder:

java -cp <path-to-analysis-jar> -Xmx8g -Xss60m de.fraunhofer.iem.crypto.CogniCryptAndroid \
      <path-to-apk> <path-to-android-platforms> <path-to-crysl-rules> <output-dir>

If specified, the analysis generates a report file CogniCrypt-Report.txt along with the .jimple output of the classes the analysis found misuses in. The format of the report file follows that described above.

Note, depending on the analyzed application, the analysis may require a lot of memory and a large stack size. Remember to set the necessary heap size (e.g. -Xmx8g) and stack size (e.g. -Xss60m).