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Summary
Affected platforms
The following platforms are known to be affected:
Threat details
Introduction
First observed in 2015, Agent Tesla is a .NET-based spyware. It has gone through numerous updates to add extra functionality and is commonly seen being sold on dark net sites.
First observed in the wild in 2014, Agent Tesla is delivered via malicious Microsoft Word documents distributed in spam or phishing campaigns. Once opened these documents ask the user to enable macros, at which point the infection process is initiated. An executable file, POM.exe, is extracted to act as an installer. It drops two further files, filename.exe and filename.vbs, before executing filename.vbs and exiting itself. This file will then add itself to the registry before executing filename.exe.
Agent Tesla collects keystrokes, screenshots and clipboard files. It will also attempt to gather passwords and credentials from a number of applications. This information is then sent to a command and control server using either HTTP POST or SMTPS.
Delivery
Agent Tesla is delivered via malicious Microsoft Word documents distributed in spam or phishing campaigns. Once opened these documents ask the user to enable macros, at which point the infection process is initiated. An executable file, POM.exe, is extracted to act as an installer. It drops two further files, filename.exe and filename.vbs, before executing filename.vbs and exiting itself. This file will then add itself to the registry before executing filename.exe.
Activities
Agent Tesla collects keystrokes, screenshots and clipboard files. It will also attempt to gather passwords and credentials from a number of applications. This information is then sent to a command and control server using either HTTP POST or SMTPS.
Threat updates
| Date | Update |
|---|---|
| 4 Feb 2021 |
Agent Tesla ramps up its game in bypassing security walls, attacks endpoint protection.
On Tuesday, Sophos researchers said that two new variants of the Remote Access Trojan (RAT) are targeting Microsoft Anti-Malware Software Interface (AMSI), scanning and analysis software designed to prevent malware infections from taking hold. Agent Tesla operators will now attempt to tamper with AMSI to degrade its defences and remove endpoint protection at the point of execution. If successful, this allows the malware to deploy its full payload. |
Remediation advice
To prevent and detect an infection, NHS Digital advises that:
- Secure configurations are applied to all devices.
- Security updates are applied at the earliest opportunity.
- Tamper protection settings in security products are enabled where available.
- Obsolete platforms are segregated from the rest of the network.
- IT usage policies are reinforced by regular training to ensure all users know not to open unsolicited links or attachments.
- Multi-factor authentication (MFA) and lockout policies are used where practicable, especially for administrative accounts.
- Administrative accounts are only used for necessary purposes.
- Remote administration services use strongly encrypted protocols and only accept connections from authorised users or locations.
- Systems are continuously monitored, and unusual activity is investigated, so that a compromise of the network can be detected as early as possible.
Please note that the NCSC maintains guidance for securely configuring a wide range of end user device (EUD) platforms. For further details refer to their end user device security guidance pages.
Indicators of compromise
Last edited: 5 February 2021 9:22 am