Authored by ChanUng Pak
McAfee’s Mobile Research team recently found a new Android malware, Elibomi, targeting taxpayers in India. The malware steals sensitive financial and private information via phishing by pretending to be a tax-filing application. We have identified two main campaigns that used different fake app themes to lure in taxpayers. The first campaign from November 2020 pretended to be a fake IT certificate application while the second campaign, first seen in May 2021, used the fake tax-filing theme. With this discovery, the McAfee Mobile Research team has been able to update McAfee Mobile Security so that it detects this threat as Android/Elibomi and alerts mobile users if this malware is present in their devices.
During our investigation, we found that in the latest campaign the malware is delivered using an SMS text phishing attack. The SMS message pretends to be from the Income Tax Department in India and uses the name of the targeted user to make the SMS phishing attack more credible and increase the chances of infecting the device. The fake app used in this campaign is designed to capture and steal the victim’s sensitive personal and financial information by tricking the user into believing that it is a legitimate tax-filing app.
We also found that Elibomi exposes the stolen sensitive information to anyone on the Internet. The stolen data includes e-mail addresses, phone numbers, SMS/MMS messages among other financial and personal identifiable information. McAfee has reported the servers exposing the data and at the time of publication of this blog the exposed information is no longer available.
Pretending to be an app from the Income Tax Department in India
The latest and most recent Elibomi campaign uses a fake tax-filing app theme and pretends to be from the Income Tax Department from the Indian government. They even use the original logo to trick the users into installing the app. The package names (unique app identifiers) of these fake apps consist of a random word + another random string + imobile (e.g. “direct.uujgiq.imobile” and “olayan.aznohomqlq.imobile”). As mentioned before this campaign has been active since at least May 2021.
Figure 1. Fake iMobile app pretending to be from the Income Tax Department and asking SMS permissions
After all the required permissions are granted, Elibomi attempts to collect personal information like e-mail address, phone number and SMS/MMS messages stored in the infected device:
Figure 2. Elibomi stealing SMS messages
Prevention and defense
Here are our recommendations to avoid being affected by this and other Android threats that use social engineering to convince users to install malware disguised as legitimate apps:
- Have a reliable and updated security application like McAfee Mobile Security installed in your mobile devices to protect you against this and other malicious applications.
- Do not click on suspicious links received from text messages or social media, particularly from unknown sources. Always double check by other means if a contact that sends a link without context was really sent by that person because it could lead to the download of a malicious application.
Android/Elibomi is just another example of the effectiveness of personalized phishing attacks to trick users into installing a malicious application even when Android itself prevents that from happening. By pretending to be an “Income Tax” app from the Indian government, Android/Elibomi has been able to gather very sensitive and private personal and financial information from affected users which could be used to perform identify and/or financial fraud. Even more worryingly, the information was not only in cybercriminals’ hands, but it was also unexpectedly exposed on the Internet which could have a greater impact on the victims. As long as social engineering attacks remain effective, we expect that cybercriminals will continue to evolve their campaigns to trick even more users with different fake apps including ones related to financial and tax services.
McAfee Mobile Security detects this threat as Android/Elibomi and alerts mobile users if it is present. For more information about McAfee Mobile Security, visit https://www.mcafeemobilesecurity.com
For those interested in a deeper dive into our research…
Distribution method and stolen data exposed on the Internet
During our investigation, we found the main distribution method of the latest campaign in one of the stolen SMS messages exposed in one of the C2 servers. The SMS body field in the screenshot below shows the Smishing attack used to deliver the malware. Interestingly, the message includes the victim’s name in order to make the message more personal and therefore more credible. It also urges the user to click on a suspicious link with the excuse of checking an urgent update regarding the victim’s Income Tax return:
Figure 3. Exposed information includes the SMS phishing attack used to originally deliver the malware
Elibomi not only exposes stolen SMS messages, but it also captures and exposes the list of all accounts logged in the infected devices:
Figure 4. Example of account information exposed in one of the C2 servers
If the targeted user clicks on the link in the text message, a phishing page will be shown pretending to be from the Income Tax Department from the Indian government which addresses the user by its name to make the phishing attack more credible:
Figure 5. Fake e-Filing phishing page pretending to be from the Income Tax Department in India
Each targeted user has a different application. For example in the screenshot below we have the app “cisco.uemoveqlg.imobile” on the left and “komatsu.mjeqls.imobile” on the right:
Figure 6. Different malicious applications for different users
During our investigation, we found that there are several variants of Elibomi for the same iMobile fake Income tax app. For example, some iMobile apps only have the login page while in others have the option to “register” and request a fake tax refund:
Figure 7. Fake iMobile screens designed to capture personal and financial information
The sensitive financial information provided by the tricked user is also exposed on the Internet:
Figure 8. Example of exposed financial information stolen by Elibomi using a fake tax filling app
Related Fake IT Certificate applications
The first Elibomi campaign pretended to be a fake “IT Certificate” app was found to be distributed in November 2020. In the following figure we can see the similarities in the code between the two malware campaigns:
Figure 9. Code similarity between Elibomi campaigns
The malicious application impersonated an IT certificate management module that is purposedly used to validate the device in a non-existent verification server. Just like the most recent version of Elibomi, this fake ITCertificate app requests SMS permissions but it also requests device administrator privileges, probably to make more difficult its removal. The malicious application also simulates a “Security Scan” but in reality what it is doing in the background is stealing personal information like e-mail, phone number and SMS/MMS messages stored in the infected device:
Figure 10. Fake ITCertificate app pretending to do a security scan while it steals personal data in the background
Just like with the most recent “iMobile” campaign, this fake “ITCertificate” also exposes the stolen data in one of the C2 servers. Here’s an example of a stolen SMS message that uses the same log fields and structure as the “iMobile” campaign:
Figure 11. SMS message is stolen by the fake “ITCertificate” using the same log structure as “iMobile”
Interesting string obfuscation technique
The cybercriminals behind these two pieces of malware designed a simple but interesting string obfuscation technique. All strings are decoded by calling different classes and each class has a completely different table value
Figure 12. Calling the de-obfuscation method with different parameters
Figure 13. String de-obfuscation method
Figure 14. String de-obfuscation table
The algorithm is a simple substitution cipher. For example, 35 is replaced with ‘h’ and 80 is replaced with ‘t’ to obfuscate the string.
Appendix – Technical Data and IOCs