Description of Campaign
RustyBuer is a loader malware and is a new variant of the original Buer Loader that first appeared 2019. The new variant differs from the previous Buer Loader as it is written in the Rust programming language. It is often delivered through spear-phishing with malicious attachments or links and is often used to collect system information to upload to a C2 and receive additional malware to further infect the target. RustyBuer functions in many of the same ways as the original Buer; checking for signs of debugger software, virtual machine or sandbox presence to evade detection and checks the language and localization settings of the system to assure it doesn't run on computers located in CIS. Although the malware has been rewritten it is developed to maintain backward compatibility with previous infrastructure.
The McAfee Enterprise ATR Team gathers and analyzes information from multiple open and closed sources before disseminating intelligence reports.
This campaign was researched by Proofpoint and shared publicly.
How to use this article:
- If a Threat Hunting table has been created, use the rules contained to search for malware related to this campaign.
- Review the product detection table and confirm that your environment is at least on the specified content version.
To download the latest content versions, go to the Security Updates page.
- Scroll down and review the "Product Countermeasures" section of this article. Consider implementing them if they are not already in place.
- Review KB91836 - Countermeasures for entry vector threats.
- Review KB87843 - Dynamic Application Containment rules and best practices.
- Review KB82925 - Identify what rule corresponds to an Adaptive Threat Protection and Threat Intelligence Exchange event.
This Knowledge Base article discusses a specific threat that is being tracked. The list of IOCs will change over time; check MVISION Insights for the latest IOCs.
Campaign IOC
| Type |
Value |
| SHA256 |
3ABED86F46C8BE754239F8C878F035EFAAE91C33B8EB8818C5BBED98C4D9A3AC |
| DOMAIN |
serevalutinoffice.com |
| DOMAIN |
orderverification-api.com |
| DOMAIN |
gerstaonycostumers.com |
| DOMAIN |
authcert-ca.com |
| DOMAIN |
ocumentssign-api.com |
| DOMAIN |
docusigner-api.com |
| DOMAIN |
miyfandecompany.com |
| URL |
https://cembank-api.com |
| URL |
http://213.252.244.114/ayhtvcgcfcfrgcdxdxdrcrhj |
| URL |
https://techlog.xyz/page.icore |
| IP-DST |
213.252.244.114 |
Minimum Content Versions:
| Content Type |
Version |
| V2 DAT (VirusScan Enterprise) |
9977 |
| V3 DAT (Endpoint Security) |
4429 |
Detection Summary
| IOC |
Scanner |
Detection |
| 3ABED86F46C8BE754239F8C878F035EFAAE91C33B8EB8818C5BBED98C4D9A3AC |
AVEngine V2 |
Buer-injector.a |
| AVEngine V3 |
Buer-injector.a |
| JTI (ATP Rules) |
JTI/Suspect.196612!65d160b89f6f |
| RP Static |
- |
| RP Dynamic |
- |
Minimum set of Manual Rules to improve protection to block this campaign
IMPORTANT: Always follow best practices when you enable new rules and signatures.
When you implement new rules or signatures, always set them to Report mode first and check the alerts generated. Resolve any issues that arise and then set the rules to Block. This step mitigates against triggering false positives and allows you to refine your configuration.
For more information, see KB87843 - List of and best practices for Endpoint Security Dynamic Application Containment rules.
Endpoint Security - Advanced Threat Protection:
Rule ID: 4 Use GTI file reputation to identify trusted or malicious files
Aggressive set of Manual Rules to improve protection to block this campaign
IMPORTANT: Always follow best practices when you enable new rules and signatures.
When you implement new rules or signatures, always set them to Report mode first and check the alerts generated. Resolve any issues that arise and then set the rules to Block. This step mitigates against triggering false positives and allows you to refine your configuration.
For more information, see KB87843 - List of and best practices for Endpoint Security Dynamic Application Containment rules.
Host Intrusion Prevention:
Rule ID: 1148 CMD Tool Access by a Network Aware Application
Rule ID: 6010 Generic Application Hooking Protection
Rule ID: 6011 Generic Application Invocation Protection
