Affected Platforms: Microsoft Windows
Impacted Users: Microsoft Windows
Impact: The stolen information can be used for future attack
Severity Level: High

Many game makers allow users to alter a game's appearance or behavior to increase its enjoyment and replay value. Players can often also download packages created by others. However, this is also a chance for attackers to distribute their malware. This article examines a batch stealer distributed via a crafted Minecraft source pack.

The zEus stealer malware has been added to a source pack that was being shared on YouTube. The name—zEus—is from a previous variant of this malware. The variant (d9d394cc2a743c0147f7c536cbb11d6ea070f2618a12e7cc0b15816307808b8a) is also distributed via a Minecraft source pack, but it’s embedded in a WinRAR self-extract file. The self-extract file mimics a Windows screensaver file. It runs the stealer and opens the image used as a file icon. It’s an image from the Internet with the string “zEus” added. This name is also found in a profile of the Discord webhook receiving stolen data.

Figure 2: The author’s name of the webhook is zEus

Infection Vector

When a victim executes the zEus stealer, it checks whether it is being analyzed. If not, it collects sensitive information and drops script files to make the attack more flexible. The zEus stealer creates folders in C:\ProgramData to save stolen data and malicious script files.

Figure 4: Aetherium.bat was added to an existing pack

Anti-analysis

zEus checks whether it is being analyzed by comparing the computer name and currently running processes with blacklists.

Computer name blacklist:

WDAGUtilityAccount, Abby, Peter, Wilson, hmarc, patex, JOHN-PC, RDhJ0CNFevzX, kEecfMwgj, Frank, 8Nl0ColNQ5bq, Lisa, John, george, PxmdUOpVyx, 8VizSM, w0fjuOVmCcP5A, lmVwjj9b, PqONjHVwexsS, 3u2v9m8, Julia, HEUeRzl, BEE7370C-8C0C-4, DESKTOP-NAKFFMT, WIN-5E07COS9ALR, B30F0242-1C6A-4, DESKTOP-VRSQLAG, Q9IATRKPRH, XC64ZB, DESKTOP-D019GDM, DESKTOP-WI8CLET, SERVER1, LISA-PC, JOHN-PC, DESKTOP-B0T93D6, DESKTOP-1PYKP29, DESKTOP-1Y2433R, WILEYPC, WORK, 6C4E733F-C2D9-4, RALPHS-PC, DESKTOP-WG3MYJS, DESKTOP-7XC6GEZ, DESKTOP-5OV9S0O, QarZhrdBpj, ORELEEPC, ARCHIBALDPC, JULIA-PC, d1bnJkfVlH, QDAVNJRH

Program blacklist:

httpdebuggerui, wireshark, fiddler, vboxservice, df5serv, processhacker, vboxtray, vmtoolsd, vmwaretray, ida64, ollydbg, pestudio, vmwareuser, vgauthservice, vmacthlp, x96dbg, vmsrvc, x32dbg, vmusrvc, prl_cc, prl_tools, xenservice, qemu-ga, joeboxcontrol, ksdumperclient, ksdumper, joeboxserver

Information Stealing

The zEus stealer grabs a wide range of information. It creates individual text files for each piece of information and saves them to corresponding folders. The folders for stolen information are in C: \ProgramData\STEALER, including the PCINFO, IPINFO, HARDWARE, BROWSERS, STEAL, LDB, and SESSION folders.

PCINFO

This folder contains two folders: IPINFO and HARDWARE. zEus looks up the victim’s IP address and related details using the online tools My External IP, ipapi, and ip-api. The results are saved as text files in the IPINFO folder. Using the IP address, zEus queries for further information from the tools, including the internet service provider, location details such as city, longitude, and latitude, and postal code. In addition, it collects the status of whether the victim is using a proxy server and if a mobile network is being used.

Figure 5: The data from online tools is saved to the IPINFO folder

Next, zEus uses command-line utilities and PowerShell to collect hardware information and saves the results in the HARDWARE folder, including currently running processes, OS version, product key, hardware ID, system configuration, installed programs, and WIFI password.

BROWSERS

zEus copies files for login data and user preferences from the browsers’ profile path and stores them in corresponding folders. Below are the target browsers:

Chrome, Opera, Brave, Vivaldi, Edge, Firefox

From these browsers, it grabs files for login data and an encryption key for a password (if necessary). It then steals cookies, history, shortcuts, and bookmarks.

STEAL

This folder contains login data copied from the following software:

Steam, osu!, Roblox, Growtopia, Discord

The files are mostly copied from the software’s data path. In addition, zEus also searches for discord_backup_codes.txt in the Downloads folder. Discord_backup_codes.txt contains backup code that helps users log in when they lose their devices for multi-factor authentication (MFA). As a result, the zEus stealer tries to get the backup code from a default location for downloaded files.

LDB

The LDB folder only stores .ldb files copied from %appdata%\discord\Local Storage\leveldb. From these .ldb files, the attacker can extract Discord tokens containing account and password information and then log into the victim’s account.

SESSION

zEus also copies various data from the following path to the SESSION folder. Not only do these files contain credentials, but the attacker also collects information about the victim. For example, it copies the Logs folders from the parent folder of EpicGamesLauncher, which contains debug logs about EpicGamesLauncher. Additionally, it copies the parent folders of game companies like Battle.net and Electronic Art. With this knowledge, the attacker can know which games are popular with the victim and how to disguise the malware to achieve the next attack.

zEus stealer also drops KEYWORDSEARCHER.bat and Keyword.txt to the STEALER folder. The batch file helps users search for keywords they want in a folder, and the text file is its README. After data collection, the STEALER folder is compressed into a zip file—STEALER.zip—and deleted. KEYWORDSEARCHER.bat and Keyword.txt are not used by the zEus stealer.

Finally, zEus organizes the attack result and sends it with STEALER.zip attached. The result shows whether it has successfully stolen the items that should be in the STEALER folder, along with the following information:

Execution date, user name, computer name, processor, anti-virus software, clipboard content, installed XBOX games, cryptocurrencies, sensitive files

zEus stealer also checks whether the victim uses any of the following cryptocurrencies:

Zcash, Armory, Bytecoin, Jaxx, Exodus, Ethereum, AtomicWallet, Guarda, Coinomi

It also searches the Downloads folder for files whose names contain one of the following keywords: 

2fa, mdp, motdepasse, mot_de_passe, login, seed, key, data, db, password, secret, account, acount, paypal, banque, metamask, wallet, code, exodus, memo, compte, token, backup, recovery

These keywords are related to login mechanisms, such as 2FA (two-factor authentication), seed, and key. There are also some French keywords meaning password, bank, and account. 

Figure 6: A part of the attack result

Features in Dropped Files

Apart from information stealing, there are features performed by the script files that are dropped to C:\ProgramData\{ComputerName}:

Among these files, debugerkiller.bat, Screen.bat, and RAT.bat are executed immediately, and their paths are registered under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run to achieve persistence. To avoid suspicion, the names of Windows system files and folders are used as the value name.

Figure 7: Key values for auto-run

Kill Task Manager

zEus stealer drops debugerkiller.bat and obscures its execution to keep terminating Task Manager. This is set to auto-run to ensure the screen lock mechanism works.

Figure 8: Code in debugkiller.bat

Send Screenshot

zEus drops Screen.bat to keep sending a screenshot to the webhook every five seconds. This is executed automatically at startup to keep monitoring the victim’s computer.

Screen Lock

SYSTEMLOCK.bat and configSYSLOCK.vbs are dropped to perform this task. configSYSLOCK.vbs is the launcher for SYSTEMLOCK.bat. The attacker can execute configSYSLOCK.vbs via C2 communication. SYSTEMLOCK.bat pops up a message box telling the victim not to restart the computer and closes explorer.exe to stop the victim from interacting with most Windows items. The SYSTEMLOCK.bat then keeps executing bsod.hta, which it dropped to the ProgramData folder. This HTA file just shows a full-screen blank window. However, debugkiller.bat prevents the victim from opening Task Manager, so most well-known methods to stop a program are blocked.

Chat Box

CHATBOX.bat is dropped to allow the victim to send at most five sentences to the attacker. This can be executed via C2 communication.

Figure 9: The chat box for the victim

C2 Communication

zEus stealer drops RAT.bat to build C2 communication. RAT.bat downloads command-line instructions from onlinecontroler[.]000webhostapp[.]com to COMMANDS.txt. If the instruction is not duplicated, it will be executed, and the result will be written to HISTORY.txt later. The executed instruction is sent to the attack’s webhook to show the current situation. In addition, special messages for screen lock and chat box help the attacker with troubleshooting. RAT.bat is set to auto-run to continuously control the computer.

Figure 10: The message for screen lock

Conclusion

zEus stealer has a relatively simple attack flow, but it collects a wide variety of information that provides data for the next attack and contributes to social engineering. This is a reminder about the dangers of downloading and using files from an unknown source. Even a source pack, usually loaded by the software, can be a carrier for malware.

In addition to only downloading files from reputable sources and checking reviews of a file and author, FortiGuard Labs recommends enabling MFA as an additional protection layer. MFA prevents unauthorized account access if a password has been compromised and can also alert users to unusual account activities. We also recommend subscribing to a service like FortiRecon that automatically scans the web for leaked data.

Fortinet Protections

The malware described in this report is detected and blocked by FortiGuard Antivirus as:

BAT/Agent.DI!tr

FortiGate, FortiMail, FortiClient, and FortiEDR support the FortiGuard AntiVirus service. The FortiGuard AntiVirus engine is part of each of these solutions. As a result, customers who have these products with up-to-date protections are protected.

FortiGuard IP Reputation and Anti-Botnet Security services proactively block these attacks by aggregating malicious source IP data from the Fortinet distributed network of threat sensors, CERTs, MITRE, cooperative competitors, and other global sources that collaborate to provide up-to-date threat intelligence about hostile sources.

FortiRecon is a SaaS-based Digital Risk Prevention service backed by FortiGuard Labs cybersecurity experts. It scans the dark web to provide timely threat intelligence on threat actor activity, including leaked data, so organizations can respond rapidly to and shut down active threats. It can also detect evidence of attacks in progress and provide critical information about threat actor motivations and TTPs.

If you believe this or any other cybersecurity threat has impacted your organization, please contact our Global FortiGuard Incident Response Team.

IOCs

C2 Server

onlinecontroler[.]000webhostapp[.]com/

panel-controller[.]000webhostapp[.]com/

Discord Webhooks

hxxps[:]//discord[.]com/api/webhooks/1212818346157015070/2v0xe2vrxFGv65
MRE9qvICmsJw-5e_pq_28xscGybiY1ScEyEiSKMC_zFffr3KkuAimX

hxxps[:]//discord[.]com/api/webhooks/1212821302671581224/L30ylYucowXO_
rm7sUpdwA8DLbYet6NyvUsNV60EP1o1HnF-2M-UPsvatVGQY0ctO9Vk

hxxps[:]//discord[.]com/api/webhooks/1212818346157015070/2v0xe2vrxFGv65
MRE9qvICmsJw-5e_pq_28xscGybiY1ScEyEiSKMC_zFffr3KkuAimX

hxxps[:]//discord[.]com/api/webhooks/1212821302671581224/L30ylYucowXO_
rm7sUpdwA8DLbYet6NyvUsNV60EP1o1HnF-2M-UPsvatVGQY0ctO9Vk

hxxps[:]//discord[.]com/api/webhooks/1212818346157015070/2v0xe2vrxFGv65
MRE9qvICmsJw-5e_pq_28xscGybiY1ScEyEiSKMC_zFffr3KkuAimX

hxxps[:]//discord[.]com/api/webhooks/1216834085205311708/2Rx-yUIHeCnuhu
Lskpz25Ghf-YWeP6Si6oiUSN4SMQYNkeJfVJiYNC4Xy_Oj0ZNQ1qTC

hxxps[:]//discord[.]com/api/webhooks/1117543783714787458/U_DdPjJm7rM7Q
2asPiMISLTrbd3oGw3oVQ25_XU37HCmM6QIQ804SJAH4_h0AT2Vr_cv

hxxps[:]//discord[.]com/api/webhooks/1191890861622050848/iJVVE3x3xilf4Te
ZNiERydXZPF5TRE1UhM4Ew06uHn95b0k0KDViw3YnhdynrXn17OKa

hxxps[:]//discord[.]com/api/webhooks/1215746939635892344/CmKTGdIvizEpR
4FgvvLJm3Bcbjg3AKlNGlwd2S-yIO-GRBXZZbn0OwG39kKnx7mDur4T

hxxps[:]//discord[.]com/api/webhooks/1223978005127364659/3E0hHtDqDOHQ
JBaG8ifspilk2mY8E1s4KeQY36inBq-tq5q6aZex8U0YJVxVlloFJj5X

hxxps[:]//discord[.]com/api/webhooks/1224075124005929020/kA4IFZrIXBl_d1Y
4I0sMHhF1cZzXvC-yEo5HzSk6Jzq_I0k1PCc1idn4FmqSC2UMljdD

Files

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