In November 2022, CYFIRMA detected a cyber-attack on an intelligence operative in India. In this attack, the threat actor was seen leveraging a strategic social engineering attack to deliver and install the .APK on the victim’s mobile. The threat actor requested the victim to share unknown files in encrypted form via an android app, which was malicious. The malicious app was instantly attached with a direct message on telegram. Upon installing, the malicious Android Package, an app with a random icon led to a dummy sign-up and login page, followed by setting up a new pattern lock. The icon after installation and the icon after opening the app were both different from each other. The threat actor has created the app as a decoy of an encrypted file-sharing app. However, the malicious .APK is just a dummy app with a pattern lock, login page, and sign-up page. The layer of the pattern lock page is inserted to make the victim believe the app is a genuine encrypted file-sharing platform.
Research revealed the threat actor Bahamut was behind the attack. Our team with high confidence attributed the attack to Bahamut APT. Through our investigation, we have found that IOCs that we fetched from the malicious android package were earlier associated with the Bahamut. The threat actor is known for conducting cyber strikes in the middle eastern region and South Asian region. The code in previous malicious apps that was used by Bahamut is similar to the .APK that was used in the recent attack. Earlier .APK with the name “SecureVpn” ( b65a8edc06bbeb598e495ccc44dc40e77ab2ef0ab11e136a0a10c24970640b42) was widely used for mass attacks on Android users. However, this is the first time, we have observed Bahamut using a fake Secure File sharing app in a strategic social engineering attack. This is the first time CYFIRMA observed the threat actor Bahamut targeting intelligence operatives, in fact, cyber-attack on intelligent assets is a rare occurrence in cyber espionage operations. Bahamut is specialized in targeting individuals with strategic social engineering attacks, they take time and showcase the ultimate level of patience while engaging with victims.
The threat actor leveraged strategic social engineering. CYFIRMA was able to get the screenshot of actual the attack taking place through telegram. In the below screenshot, the threat actor asks the victim to use the app to share the files in encrypted form. The threat actor kept the engagement going for the past few days and suddenly took leverage of earned trust to make the victim install the app. However, the attack was detected and dismantled before it could leave any damage.
Figure 1. Screenshots of Bahamut delivering .APK payload.
System: Android System
SHA256: 45a6a0b2b02a9d288afba1ff41c689be9b9bd40ee862aa4bd6b036e3f0a4c3ab Package Name: com.secure.vault
File Type: APK
Upon Installation, an app with the name Vault reflects on Apps Menu.
Figure 2. Vault application stationed in App Menu.
The below figure shows that the Android Vault Application requests access permission at the start.
Figure 3. Usage access permission.
After opening the app, it takes the victim to set the pattern lock. This page was added to make the victim believe that the app is a legitimate secure file-sharing app.
Figure 4. Setup Pattern Lock
After setting the pattern lock, the app opens up the next page with login and Sign-Up options.
Figure 5. Login Activity.
This is the last page, where the victim is supposed to register for the service.
Figure 6. Dummy Sign-Up Page.
Application Certificates and Signatures
The META-INF folder contains the signature file and self-signed public key certificate. GOOGLE.RSA certificate can be viewed using the key tool.
Figure 7. Keytool.
This XML contains the necessary essential information about the application and its components, required permissions, used libraries and Java packages, and more, to run on the Android System.
As the manifest file is encoded, decode the file contents using the apktool with the d option.
Figure 8. Apktool d option.
The apktool decodes all binary XML files, including Android manifests and resources, but also disassembles the DEX file with baksmali. The apktool generates, [.]smali files, which can be examined by any text editor.
The apktool output shows the below files/folders structure.
Figure 9. APKtool Output.
Application main activities (activities are nothing but pages in the App) & icon information from the manifest file.
Figure 10. Main Activity & Icon.
SDK & API Level information from the manifest file.
Figure 11. SDK & API Level information.
Permissions from the manifest file. The permissions clearly indicate the malicious .APK was put on the job to fetch maximum information from the victim’s mobile.
Figure 12. Permissions.
Below are a few dangerous permissions that are malicious. .APK is gaining access to them.
|1||READ_SMS||This allows attackers to delete and read outgoing and incoming SMSs|
|2||READ_CALL_LOG||This allows actors to read and fetch call logs.|
|3||READ_CONTACTS||This permission allows TA to read and fetch contacts.|
|4||READ_EXTERNAL_STORAGE||This allows threat actors to explore and fetch data from the file manager.|
|5||WRITE_EXTERNAL_STORAGE||This allows threat actors to delete and move files.|
|6||GET_ACCOUNTS||This allows the threat actor to extract emails and usernames used for login into various internet platforms|
|7||CAMERA||This allows the threat actor to use a front and back camera.|
|8||ACCESS_FINE_LOCATION||Allows the threat actor to fetch precise locations and track the live movement of mobile phones.|
|9||WRITE_CALL_LOG||This allows the threat actor to make calls and delete them from call logs.|
|10||WRITE_CONTACTS||This allows the threat actor to delete and add contacts.|
Android Vault Application collects information on the device’s contacts, SMS, and call logs in the initial stage.
Figure 13. Lock service for collecting information.
Below is the module, which exploits “android.permission.ACCESS_FINE_LOCATION” permission to fetch the precise location of the hacked user.
Figure 14. Exploiting one of the permissions.
Below is the module, revealing what sort of information this malicious .APK collects, and sends to the C2. It fetches call logs, SMS logs, and live coordinates and tracks messages by keystrokes, by abusing accessibility from apps like Telegram, Signal, Viber, IMO, and Conion.
Figure 15. List of Information, the malicious app steals from compromised users.
Analyze the code from SplashActivity, as the app execution starts from the main activity & Application subclasses.
Figure 16. Usage Access Setting
Android APIs used in this sample is based on static analysis.
Get SIM Serial Number
Get System Service
UDP Datagram Socket
Query Database of SMS, Contacts, etc. TCP Socket
Get Device ID, IMEI, MEID/ESN etc. Crypto
Java Reflection Method Invocation
URL Connection to file/http/https/ftp/jar Local File I/O Operations
The const-string is being used to move a value (string value) into the registers (v0, v1, etc.). The invoke- direct is used to invoke the instance methods. The invoke-direct accepts two arguments (po register and a reference to the method that needs to be called).
Figure 17. Smali Code Analysis.
The below screenshot shows the module collects data in SQL queries.
Figure 18. SQL queries.
The module contains DNS and IP which belongs to the command-and-control server.
Figure 19. URL & IP.
|1||TA0003: Persistence||T1398: Boot or Logon Initialization Scripts|
|2||TA0032: Discovery||T1418: Software Discovery
T1420: File and Directory Discovery
T1426: System Information Discovery
|3||TA0009: Collections||T1430: Location Tracking
T1429: Audio Capturing
T1512: Video Capture
T1417.001: Input Capture: Keylogging
T1636.002: Protected User Data: Call logs
T1636.004: Protected User Data: SMS Messages
T1636.003: Protected User Data: Contacts List
|4||TA0011: Command and Control||T1437: Application Layer Protocol: Web Protocols|
|5||TA0010: Exfiltration||T1646: Exfiltration Over C2 Channel|
Bahamut is Iran’s state-sponsored Advance Persistent threat group, communicating in the Urdu language for strategic social engineering attacks. This indicates the threat actor knows its target very well and is focused to compromise the individual target by going a bit far. In another example, the threat actor injected code to track keystrokes entered on Conion. Conion is a Tor-based chatting app, that is currently considered to be an alternative to Signal, which is not well known to many, which again proves the threat actor is clear with their aim. The mobile campaign operated by the Bahamut APT group is still active. Further, the spyware code, and hence its functionality, is the same as in previous campaigns, including collecting data to be exfiltrated in a local database, before sending it to the operators’ server, a tactic rarely seen in mobile cyberespionage apps.