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CISO Briefing: How Herodotus Trojan Steals Credentials Undetected by Mimicking User Interaction — by CyberDudeBivash

By CyberDudeBivash · 01 Nov 2025 · cyberdudebivash.com · Intel on cyberbivash.blogspot.com

LinkedIn: ThreatWirecryptobivash.code.blog

ANDROID TROJAN • HERODOTUS • BEHAVIORAL MIMICRY

Situation: A new, highly advanced Android banking trojan, dubbed “Herodotus,” is actively bypassing bank-side fraud detection. This is not a standard trojan. After stealing credentials via an overlay attack, it uses “human mimicry” to enter them, complete with human-like delays and “typing jitter,” to defeat User and Entity Behavior Analytics (UEBA) and anomaly detection.

This is a decision-grade CISO brief. Attackers are now actively training their malware to look human, rendering your expensive bot-detection and anomaly detection platforms blind. This is an “adversarial AI” attack in the wild. We are dissecting this TTP and explaining why the *only* defense is on the endpoint, not the server.

TL;DR — A new Android malware named “Herodotus” is stealing banking info, and it’s smart.

• TTP 1 (Theft): It uses a standard “overlay attack” (via Accessibility Services) to show a fake login screen over your *real* banking app, stealing your Customer ID and Password.
• TTP 2 (Evasion): This is the new part. Instead of “pasting” your credentials (a bot action), it “types” them in with randomized, human-like delays. It *mimics* your behavior to fool your bank’s AI-powered fraud detection.
• The Risk: Your bank will not detect the fraudulent login. It looks “human.” The malware also intercepts your SMS OTP, giving it full 2FA bypass.
• THE ACTION: The *only* defense is on your device. 1) Audit Accessibility Services NOW. 2) Never sideload apps. 3) Use a premium mobile security suite (like Kaspersky) to block the trojan.

Contents

1. Phase 1: The “Herodotus” TTP (Why it’s Smarter than other Trojans)
2. Phase 2: The Kill Chain (From .APK to Empty Bank Account)
3. Phase 3: Why Your Bank’s UEBA & Bot-Detection Fails
4. The Emergency “Hunt & Harden” Plan (for your device)
5. Tools We Recommend (Partner Links)
6. CyberDudeBivash Services & Apps
7. FAQ

Phase 1: The “Herodotus” TTP (Why it’s Smarter than other Trojans)

For years, the arms race has been simple: banking trojans (like Chameleon, Anubis) steal credentials, and banks use User and Entity Behavior Analytics (UEBA) to stop the fraudulent login. The bank’s AI is trained to spot anomalies.

The “Stupid Bot” (Old Attack):

• A trojan steals your login: `user123` / `pass456`.
• The trojan logs in by *pasting* the credentials.
• Total login time: 0.2 seconds.
• Result: The bank’s UEBA system flags this as a “bot,” a clear anomaly, and blocks the login.

The “Herodotus Bot” (New Attack):

Herodotus is a “smart bot.” It’s an “adversarial AI” attack. It understands the bank’s detection method and is built to defeat it. It uses behavioral mimicry.

• The trojan steals your login: `user123` / `pass456`.
• It then initiates its *own* login and “types” the credentials:
  • `u`… (wait 0.12s) … `s` … (wait 0.21s) … `e` … (wait 0.15s) … `r` …
• It may even add “jitter,” moving the mouse slightly or adding a longer pause, as if the “human” is thinking.
• Total login time: 5.8 seconds (which is in the “normal” human range).
• Result: The bank’s UEBA system sees a login attempt that looks *perfectly human*. It matches your normal behavioral baseline. The login is allowed.

This is a massive evolution. The malware is no longer just a “credential thief”; it’s a “behavioral impersonator.”

Phase 2: The Kill Chain (From .APK to Empty Bank Account)

This is how the full attack plays out on a victim’s device.

Stage 1: Initial Access (The “Sideload”)

The attack begins with a spear-phishing text (SMS) or WhatsApp message. This is *not* from the Google Play Store. The message creates urgency:

“Your electricity bill is overdue. Please install our new payment app to avoid disconnection.”

The user, in a panic, downloads the malicious `.apk` file (e.g., `payment.apk`) and “sideloads” it.

Stage 2: Permission Abuse (The “Master Key”)

The fake app opens. It’s a “loader.” It *immediately* pesters the user for two critical permissions:

1. Accessibility Services: It claims it needs this to “read the screen for you” or “auto-fill forms.” This is the master key. This permission allows the trojan to *see everything on your screen* and *perform actions on your behalf* (like drawing over other apps).
2. Read SMS: It claims it needs this to “auto-read OTPs for convenience.” This is the 2FA bypass.

Stage 3: Credential Theft (The “Overlay”)

The malware now lies dormant, waiting. The user, forgetting about the fake app, opens their *real* banking app (e.g., HDFC, ICICI, SBI).
The Herodotus trojan, using its Accessibility permission, *detects* the banking app opening. It instantly draws an *identical, fake* login screen *over* the real one.
The user, unsuspecting, types their Customer ID and Password into the *fake* screen. The trojan captures these keystrokes and sends them to the attacker’s Command & Control (C2) server.

Stage 4: Fraudulent Login (The “Mimicry”)

This is where Herodotus shines.

1. The attacker’s C2 server initiates a *new* login to the bank, either from the device or a server.
2. It uses the stolen credentials, but “types” them in slowly, using behavioral mimicry to look human.
3. The bank’s UEBA system approves the login. The bank sends an SMS OTP.
4. The Herodotus trojan on the phone *intercepts* the SMS, steals the OTP, sends it to the C2, and *hides the SMS notification*.
5. The attacker enters the OTP. They now have full 2FA-bypassed access to the account.

Phase 3: Why Your Bank’s UEBA & Bot-Detection Fails

This TTP is a direct assault on the anomaly detection models that banks and e-commerce sites rely on. These platforms are spending millions on “bot-detection” and UEBA. They are building behavioral baselines for every user.

Herodotus defeats this model by *becoming the baseline*.

• Defeats Timing Analysis: The login-time is not anomalous.
• Defeats Keystroke Dynamics: The “typing” has human-like jitter.
• Defeats Location (Potentially): If the fraudulent login is initiated *from the victim’s own device*, the IP address, device ID, and location are *all* correct.

This proves a critical CISO-level concept: You cannot trust the server-side analytics if the client-side endpoint is compromised. The bank’s AI is being fed “clean,” “human” data by the attacker. The entire model collapses.

Service Note: This is why BYOD (Bring Your Own Device) is your #1 corporate risk. This *exact* trojan on an employee’s phone can connect to your VPN. It can then use this *same mimicry* to steal their M365, Salesforce, or corporate SSO credentials. Our Mobile VAPT & Red Team engagements are built to simulate this exact threat.
Book a Mobile VAPT Engagement →

The Emergency “Hunt & Harden” Plan (for your device)

Since you cannot rely on your bank to catch this, the defense *must* be on your own device. This is a client-side problem.

Step 1: HUNT (Audit Accessibility Services NOW)

This is the master key. Go here immediately:

1. Go to Settings > Accessibility.
2. Find “Installed apps” or “Downloaded services.”
3. AUDIT THIS LIST. The *only* apps with this permission should be ones you 100% trust and require (e.g., a password manager like Bitwarden, or a trusted antivirus like Kaspersky).
4. If you see *any* “utility,” “cleaner,” “game,” or “payment” app you don’t recognize, TAP IT AND TURN IT OFF. This is non-negotiable.

Step 2: HARDEN (Audit SMS & Install Permissions)

• SMS Permissions: Go to Settings > Apps > Permission manager > SMS. Revoke this permission from *everything* except your main SMS app (e.g., Google Messages).
• Stop Sideloading: Go to Settings > Apps > Special app access > Install unknown apps. Make sure this is “Not allowed” for all your browsers and messaging apps.

Step 3: PROTECT (Install Mobile Security)

You need a real-time security scanner on your phone that can *block* the trojan `.apk` file *before* you can even install it. This is what a Mobile EDR or Mobile Antivirus does.

The Tool We Recommend: This is the exact threat Kaspersky Premium is built for. Its Android app provides real-time, automated malware scanning that finds these trojans *before* they can ask for permissions. It also blocks the phishing links used to spread them.
Get Kaspersky Premium (Partner Link) →

Recommended by CyberDudeBivash (Partner Links)

You need a layered defense. Here’s our vetted stack for this specific threat.

Kaspersky (Premium/EDR)
The #1 defense. Its Android agent blocks the malicious `.apk` on download. This is your best protection.Hardware Keys (via AliExpress)
The *ultimate* fix. This malware can steal an SMS OTP. It *cannot* steal a physical FIDO2/YubiKey.TurboVPN
The initial phish can be delivered via Man-in-the-Middle on public Wi-Fi. A VPN encrypts this channel.

Edureka — Mobile Security Training
Train your SecOps team on Mobile Threat Hunting and how to detect these TTPs in a BYOD environment.Alibaba Cloud (Global)
If you are a FinTech, build your *own* secure-by-design mobile backend on isolated, secure cloud infra.Rewardful
Run a bug bounty program on your mobile app. Pay white-hats to find these flaws before attackers do.

CyberDudeBivash Services & Apps

We don’t just report on these threats. We hunt them. We are the expert team you call when your BYOD policy becomes your biggest liability. We find the blind spots.

• Mobile VAPT & Red Teaming: We will simulate this *exact* Herodotus attack on your corporate-enrolled devices to see if your MDM/EDR can detect it.
• Managed Detection & Response (MDR): Our 24/7 SecOps team becomes your “human sensor,” hunting for the TTPs of a compromised mobile device on your VPN.
• Emergency Incident Response (IR): If you suspect a mobile-based breach, our digital forensics team can trace the attack and eradicate it.
• PhishRadar AI — Our app to detect and block the initial SMS/WhatsApp phishing text *before* the user can click it.
• SessionShield — Protects your corporate app sessions *even if* the user’s credentials and OTP are stolen and mimicked.

Book a Mobile VAPT EngagementExplore 24/7 MDR & IR ServicesSubscribe to ThreatWire

FAQ

Q: How is Herodotus different from other Android trojans (like Chameleon or Anubis)?
A: The behavioral mimicry. Most trojans are “smash and grab”—they steal credentials and paste them as fast as possible, which is a clear bot signal. Herodotus is “slow and smart”—it *impersonates* your human typing behavior to bypass the bank’s AI-powered bot detection.

Q: I use an iPhone. Am I safe?
A: From *this specific* TTP, yes. Apple’s iOS is sandboxed differently and does not allow this kind of “Accessibility Service” overlay attack. It also does not allow “sideloading.” This is a purely Android-based threat.

Q: I just found a weird app in my Accessibility settings! What do I do NOW?
A: 1. Revoke the permission. 2. Uninstall the app. 3. Call your bank *immediately* from a *different, clean device*. Tell them you suspect a mobile breach and have them review all recent transactions. 4. From a clean device, change your banking password. 5. Run a full scan with a tool like Kaspersky.

Q: How does this affect my *company*?
A: This is a critical BYOD (Bring Your Own Device) threat. The same trojan on your employee’s phone (which is connected to your corporate VPN) can use the *same TTPs* to steal their M365, Salesforce, and SSO credentials. It will “mimic” their typing to bypass *your* UEBA. This is why you need a Mobile VAPT to test your defenses.

Next Reads

• [Related Post: The 5 “Fileless” Attack TTPs Your EDR is Missing]
• Daily CVEs & Threat Intel — CyberBivash
• CyberDudeBivash Apps & Services Hub

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