Corebot
Table of Contents
Overview
Trojan:Win32/Corebot is a highly sophisticated, modular **Banking Trojan** and **Infostealer**. Originally discovered in 2015 acting as a generic credential stealer, Corebot rapidly evolved, integrating a massive web-inject plugin that allowed it to specifically target online banking portals, intercept two-factor authentication (2FA), and steal financial data in real-time. Its highly modular architecture means the botmaster can deploy custom plugins to adapt to new security measures instantly.
Understanding the Corebot Threat
To an end-user, Corebot operates invisibly. When they attempt to log into their bank, the website looks perfectly normal, but the trojan is actively manipulating the HTML content (Web-Injects) to harvest credentials. For a security operations center (SOC), Corebot represents a critical, high-severity breach. Its modular nature (`T1129`) means it can download secondary modules to act as a point-of-sale (POS) scraper, a cryptocurrency wallet thief, or a VNC backdoor.
Execution and Web-Inject Mechanics
Corebot is primarily distributed via highly targeted spear-phishing campaigns or exploit kits (`T1189`). Upon execution (`T1204.002`), it establishes persistence via Registry Run keys (`T1547.001`). Its core functionality relies on advanced process injection (`T1055.001`). It injects its malicious DLL into all active web browsers (`chrome.exe`, `iexplore.exe`, `firefox.exe`). Once injected, it hooks into the browser's networking APIs (like `HttpSendRequest`). When the user visits a targeted banking URL, Corebot intercepts the traffic *before* it is encrypted via SSL/TLS (`T1185`). It then uses its Web-Inject configuration file to modify the DOM of the banking page, presenting the user with fake login forms or requests for 2FA tokens, routing the stolen data directly to the C2 server.
Indicators of Compromise & Impact
The primary impact is catastrophic financial fraud, credential theft, and total compromise of the user's digital identity. Host-based IoCs include EDR alerts for DLL injection into browser processes and the presence of hidden, randomly named directories in `%AppData%` containing encrypted configuration files. Network IoCs include encrypted C2 traffic utilizing custom domain generation algorithms (DGAs).
MITRE ATT&CK Techniques
Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1185 | Browser Session Hijacking (Man-in-the-Browser Web-Injects) | Collection | ATT&CK ↗ |
T1055.001 | Process Injection: Dynamic-link Library Injection | Defense Evasion | ATT&CK ↗ |
T1129 | Shared Modules (Modular plugin architecture) | Execution | ATT&CK ↗ |
T1552.001 | Credentials In Files (Stealing stored browser passwords) | Credential Access | ATT&CK ↗ |
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-DIA | DLL Injection Analysis | Detect | T1055.001 | Monitor remote thread creation (CreateRemoteThread) and unauthorized DLL loading into core Windows processes (svchost.exe, explorer.exe). |
D3-MitBA | Man-in-the-Browser Analysis | Detect | T1185 | Deploy browser extension whitelisting and hardware-backed session binding to prevent rogue DOM and socket injection. |
D3-FPA | File Permission Auditing | Harden | T1552.001 | Scan filesystem repositories for plaintext configuration files and restrict access via Least Privilege RBAC controls. |
Tiered Detection Rules (Cisco CAIRN Model)
Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_COREBOT_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Corebot"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "corebot" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Corebot (Trojan) Execution & Triage
id: 37814a6d-4e8b-5f24-a7f7-069c377a766a
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Corebot malware family. Detects suspicious execution from temporary user
directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/corebot
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1129
- attack.t1185
- attack.t1055_001
- attack.t1552_001
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \cmd.exe
- \powershell.exe
- \cscript.exe
- \wscript.exe
CommandLine|contains:
- AppData\Local\Temp
- -WindowStyle Hidden
- /e:jscript
- bitsadmin /transfer
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_COREBOT_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Corebot tradecraft"
tier = "T3 - Attribution Fingerprint"
confidence = "High (Confirmed Family Signature)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
// Core family identifier & heuristic payload signatures
$attrib_str = "corebot" ascii wide nocase
$pe_magic = "MZ" ascii
$net_marker = "http" ascii nocase
condition:
uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}Containment & Response Steps
Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.
- Isolate the endpoint immediately to prevent the exfiltration of credentials and sever the C2 connection.
- Reset all passwords for any account accessed from the infected endpoint, prioritizing financial institutions, corporate VPNs, and email accounts.
- Capture a live memory image (RAM dump) to extract the injected Corebot modules and decrypt its web-inject configuration file to determine which banks were targeted.
- Wipe the infected system entirely and restore from a known-clean baseline image.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not assume changing passwords on the infected machine is sufficient; the trojan will simply intercept the new passwords in real-time.
- Avoid relying on standard antivirus removal; banking trojans deeply hook into the OS and often leave persistent backdoors if not properly wiped.
References & External Analysis
- Search "corebot" on VirusTotal (External Analysis)
- Search "corebot" on Any.Run (Sandbox Sandbox)
- Search "corebot" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Corebot and what threat category does it belong to?
Corebot is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Corebot establish persistence and evade defensive controls?
Corebot typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Corebot compromise?
Security teams responding to Corebot should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What secondary payloads and staging behaviors are commonly associated with Corebot?
Corebot frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors.
How can security operations teams effectively detect and hunt for Corebot across enterprise endpoints?
Defenders should hunt for Corebot by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries.
How do I remove Corebot from Windows?
Manual removal of Corebot is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
What are the main symptoms of a Corebot infection?
Symptoms of Corebot can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Trojans
Want to prevent Corebot and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/corebot.json
Ecosystem & Interactive Environments
This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.