MVISION Insights: Microsoft Exchange Servers Under Attack
Technical Articles ID:
KB94748
Last Modified: 8/10/2021
Environment
IMPORTANT: This Knowledge Base article discusses a specific threat that is being automatically tracked by MVISION Insights technology. The content is intended for use by MVISION Insights users, but is provided for general knowledge to all customers. Contact us for more information about MVISION Insights.
Summary
Description of Campaign
A financial institution in the EMEA region was targeted by an unknown threat actor. The adversary leveraged vulnerabilities in Microsoft Exchange classified under CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065. Successful exploitation allowed the actor to install a webshell on the server which was possibly a variant of the China Chopper server-side JScript. The IP addresses used in the operation for command and control do not appear to be actor-owned but more likely proxies, VPNs, and compromised servers. Multiple techniques were used including PowerShell, batch scripts, encoding, and automation to enumerate running processes and harvest credentials.
The McAfee Enterprise ATR Team gathers and analyzes information from multiple open and closed sources before disseminating intelligence reports.
This campaign was reported by researchers at Palo Alto Networks and shared publicly.
How to use this article:
- Scroll down and review the Product Countermeasures section of this article. Consider implementing them if they are not already in place.
- Review the following articles:
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 |
| IP-DST |
156.194.127.178 |
| IP-DST |
112.160.243.172 |
| IP-DST |
221.179.87.175 |
| IP-DST |
73.184.77.174 |
| IP-DST |
41.237.156.15 |
| IP-DST |
223.16.210.90 |
| IP-DST |
63.76.255.110 |
| IP-DST |
218.103.234.104 |
| IP-DST |
83.110.215.7 |
| IP-DST |
121.150.12.35 |
| IP-DST |
164.68.156.31 |
| IP-DST |
45.77.140.214 |
| IP-DST |
78.141.218.225 |
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: 5 Use GTI URL reputation to identify trusted or malicious processes
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