Security testing in mobile applications

Security testing in mobile
applications
José Manuel Ortega Candel

About me
 Centers Technician at Everis
 Computer engineer by Alicante University
 Frontend and backend developer in Java/J2EE
 Speaker site with some presentations in
mobile and security
https://speakerdeck.com/jmortega

Index
Security Testing for Mobile Apps
Risk Management & Security Threads
Vulnerabilities & Mobile Security Risks
Testing Components Security & Tools
Security Test Plan & Best Practices

White Box Testing
Static Analysis Code
Black Box Testing
Dinamyc Analysis at
Runtime

Static Application Security Testing
Source code Review Reverse engineering
Lint for Android
Studio
Sonar Plugins for
mobile
http://www.sonarqube.org

https://github.com/SonarCommunity/sonar-android

http://sourceforge.net/projects/agnitiotool
You can decompile APKs and
search calls dangerous functions.

Reverse engineering on Android
APK Tool /Dex2jar/Java Decompiler

Static analysis on iOS
Xcode Development environment
Apple Developer Tools
‘otool’ command provided by XCode can be used to
get information from iOS application binaries and can
be used to support security analysis.

Static analysis on iOS
Detect memory leaks with XCode
Clang Static Analyzer
http://clang-analyzer.llvm.org
Flawfinder(Security weakness in C/C++)
http://www.dwheeler.com/flawfinder

Dynamic Application Security Testing
Analyze Network
Traffic at runtime
Analyze Remote
Services
DroidBox for Android
Instruments for iOS
Discovering logical
vulnerabilities

 https://code.google.com/p/droidbox
Monitoring Actions
 Information leaks Network IO and File IO
 Cryptography operations SMS and Phone calls

Instruments for iOS applications
File Activity Monitoring
Memory Monitoring Process Monitoring
Network Monitoring

Application Security Analyser
python androwarn.py -i my_apk.apk -r html -v 3
Telephony identifiers exfiltration: IMEI, IMSI, MCC, MNC, LAC, CID, operator's
name...
Device settings exfiltration: software version, usage statistics, system settings, logs...
Geolocation information leakage: GPS/WiFi geolocation... Connection interfaces
information exfiltration: WiFi credentials, Bluetooth MAC adress...
Telephony services abuse: premium SMS sending, phone call composition...
Audio/video flow interception: call recording, video capture... Remote connection
establishment: socket open call, Bluetooth pairing, APN settings edit...
PIM data leakage: contacts, calendar, SMS, mails...
External memory operations: file access on SD card...
PIM data modification: add/delete contacts, calendar events... Arbitrary code
execution: native code using JNI, UNIX command, privilege escalation...
Denial of Service: event notification deactivation, file deletion, process killing, virtual
keyboard disable, terminal shutdown/reboot...

Risk Management
Intelligence
Gathering
Threat model
Vulnerabilities
OWASP
Security risks
Security
threads

Intelligence Gathering
Environmental
Analysis
Architectural
Analysis
Analyze internal
processes and structures
App [network interfaces, used
data, communication with other
resources, session management]
Runtime environment [MDM,
jailbreak/rooting, OS version]
Backend services [application
server, databases]

Intelligence Gathering
What type of device is it?
Determine Operating System version
Is the device already rooted?
Is the device passcode enabled?
What key applications are installed?
Is the device connected to network?

Thread model in Mobile applications

Functional Security threads
Authentication
Session
Management
Access Control
Input Validation
Cryptography
Error Handling and
Logging
Data Protection
Communication
Security

Security issues
Malicious Applications
– Rooting Exploits
– SMS Fraud
– Rapid Malware Production
Dynamic Analysis
– Sandbox
– Real-time Monitoring
– Mobile Specific Features
Static Analysis
– Permissions
– Data Flow
– Control Flow
Browser Attacks
– Phishing
– Click Through
Mobile Botnets
– Epidemic Spread
– Attacking Network Services
– Tracking Uninfected Devices
User Education
– Ignoring Permissions
– Phishing
– Improperly Rooting Devices
– Alternative Markets

Vulnerabilities
Third party
libraries
Components
WebView
[JavaScript+Cache]
SQLite DataBase
Multiplaftorm
libraries for hybrid apps
Shared Preferences

Vulnerabilities
1. Activity monitoring and
data retrieval
2. Unauthorized dialing,
SMS, and payments
3. Unauthorized network
connectivity (exfiltration or
command & control)
4. UI Impersonation
5. System modification
(rootkit, APN proxy config)
6. Logic or Time bomb
7. Sensitive data leakage
(inadvertent or side
channel)
8. Unsafe sensitive data
storage
9. Unsafe sensitive data
transmission
10. Hardcoded
password/keys

Vulnerabilities Analysis
Static methods
Dynamic
methods
Automatic and manual
source code analysis
Reverse Engineering
Forensic
methods
Network monitoring and
trafic analyzing
Runtime analysis
Log analysis
File permission analysis
File content analysis

Dynamic methods tools
Network monitoring and
traffic analyzing
Runtime analysis
Wireshark, BurpSuite
GNU debugger,
Snoop-it, Cycript
Mercury, Intent Sniffer,
Intent Fuzzer
File analysis androidAuditTools

Testing vulnerabilities
Data flow
Data Storage
Data leakage
Authentication
Authorization
Server-side

OWASP Mobile Security Risks
Insecure Data
Storage
Transport Layer
Protection,
HTTP/SSL
Authorization and
Authentication
Cryptography /
Encrypting data
Session handling
Weak Server Side
Controls in backend
services
Sensitive information
[passwords,API
keys,code ofuscation]
Data Leakage [cache,
logging, temp
directories]

Testing components security
Content Providers Data Storage
WebViewServices
NetWork Connections
[HTTP / SSL]
Certificates
Data Encryption
SQLite
Shared Preferences
File storage

HTTPS and SSL can protect against Man in the Middle
attacks and prevent casual snooping

Data Storage
Encrypt data
Never store user credentials
Tools like SQLCipher for storing
database in applications
No global permissions granted to
applications, using the principle of
"least privilege".

Secure Storage on Android
The access permission of the created file was set to
WORLD_READABLE / WORLD_WRITABLE
Other app could read /write the file if the file path is known.
Application data (private files) should be created
with the access permission MODE_PRIVATE
FileOutputStream fos = openFileOutput(“MyFile",
Context.MODE_PRIVATE);
fos.write(“contenido”.getBytes());
fos.close();

Insecure Data on Android
Look for file open operations using
Context.MODE_WORLD_READABLE
(translates to “1”)

Secure Storage on iOS
NSFileManager class
NSFileProtectionKey attribute
 NSFileProtectionNone – Always accessible
 NSFileProtectionComplete – Encrypted on disk
when device is locked or booting
[[NSFileManager defaultManager] createFileAtPath:[self
filePath]
contents:[@"super secret file contents“
dataUsingEncoding:NSUTF8StringEncoding]
attributes:[NSDictionary
dictionaryWithObject:NSFileProtectionComplete
forKey:NSFileProtectionKey]];

DataBase Storage
Support iOS / Android
https://www.zetetic.net/sqlcipher/open-source
256-bit AES Encrypt SQLite database
Secure Preferences on Android
https://github.com/scottyab/secure-preferences
3rd-party extensions

Cryptography
Android and iOS implement standard crypto libraries such as AES
algorithm
try{
PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt,
PBE_ITERATION_COUNT, 256);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(PBE_ALGORITHM);
SecretKey tmp = keyFactory.generateSecret(keySpec);
// Encrypt
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher encryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM);
IvParameterSpec ivspec = new IvParameterSpec(initVector);
encryptionCipher.init(Cipher.ENCRYPT_MODE, secret, ivspec);
encryptedText = encryptionCipher.doFinal(cleartext.getBytes());
// Encode encrypted bytes to Base64 text to save in text file
result = Base64.encodeToString(encryptedText, Base64.DEFAULT);
} catch (Exception e) {
e.printStackTrace()
}
Android provides the javax.crypto.spec.PBEKeySpec
and javax.crypto.SecretKeyFactory classes to facilitate
the generation of the password-based encryption key.

Avoid Data Leackage on Android
public static final boolean SHOW_LOG =
BuildConfig.DEBUG;
public static void d(final String tag, final String msg) {
if (SHOW_LOG)
Log.d(tag, msg);
}
Don't expose data through logcat on production
-assumenosideeffects class android.util.Log
{
public static *** d(...);
public static *** v(...);
public static *** i(...);
public static *** e(...);
}
Proguard configuration

Permissions in mobile apps
AndroidManifest.xml on Android
 Try to minimize permissions
<manifest package="com.example.android" …>
<uses-permission android:name=“android.permission.
ACCESS_FINE_LOCATION"/>
<uses-permission
android:name="android.permission.INTERNET" />
<uses-permission
android:name="android.permission.READ_CONTACTS" />
…
</manifest>

Permissions in mobile apps
info.plist on iOS

Vulnerability scanner on Android

Security test plan
Test cases Example
Test Title /level Encryption /critical
Test
Description
When connections are used encryption
is used for sending / receiving sensitive
data.
Details and
tools
All sensitive information (personal data,
credit card & banking information etc.)
must be encrypted during transmission
over any network or communication
link.
Expected
result
It has been declared that the
Application uses encryption when
communicating sensitive data.

Security test plan
Test cases Example
Test Title /level Passwords /critical
Test
Description
Passwords and sensitive data are not
stored in the device and not echoed
when entered into the App, sensitive
data is always protected by password.
Details and
tools
The objective of the test is to minimize
the risk of access to sensitive
information should the device be lost,
by ensuring that no authentication data
can be re-used by simply re-opening
the application

Security test plan
Test cases Example
Test Title /level Passwords /critical
Expected
result
1. Entering a password or other
sensitive data will not leave it in
clear text if completion of the fields
is interrupted but not exited.
2. Passwords, credit card details, or
other sensitive data do not remain
in clear text in the fields where they
were previously entered, when the
application is reentered.
3. Sensitive personal data should
always need entry of a password
before it can be accessed.

Best Practices
Integrate security in Continuous
Integration (CI) process
Apply encryption /decryption techniques
used for sensitive data communication
Detect areas in tested application that have
more risks to detect vulnerabilities
Install an automated security vulnerability
scanner, integrated with your continuous
integration tool

Attacker vs Defenders
Defenders Attackers
Often have limited time to
put defences in place
Can take time to plan their
attack
Have limited opportunities
to improve their defences
Can invent new ways to
attack
Need to defend against a
range of possible attacks
Need only pick the most
effective one
Need to defend all entry
points
Can choose where to
attack
Has limited resources to
defend
Can be multiple attackers

References
https://www.owasp.org/index.php/OWASP_Mobile_Security_
Project
http://developer.android.com/training/articles/security-
tips.html
OWASP Mobile Security Project
Android Security Best Practices

References
https://github.com/secmobi/wiki.secmobi.com
Tools
IOS Application Security Testing
https://www.owasp.org/index.php/IOS_Application_Security_
Testing_Cheat_Sheet

Security testing in mobile applications

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