Likely eCrime Actor Uses Filenames Capitalizing on July 19, 2024, Falcon Sensor Content Issues in Operation Targeting LATAM-Based CrowdStrike Customers

Summary

On July 19, 2024, an issue present in a single content update for the CrowdStrike Falcon® sensor impacting Windows operating systems was identified, and a fix was deployed.¹

CrowdStrike Intelligence has since observed threat actors leveraging the event to distribute a malicious ZIP archive named crowdstrike-hotfix.zip. The ZIP archive contains a HijackLoader payload that, when executed, loads RemCos. Notably, Spanish filenames and instructions within the ZIP archive indicate this campaign is likely targeting Latin America-based (LATAM) CrowdStrike customers.

Details

On July 19, 2024, a ZIP archive named crowdstrike-hotfix.zip (SHA256 hash: c44506fe6e1ede5a104008755abf5b6ace51f1a84ad656a2dccc7f2c39c0eca2) was uploaded to an online malware-scanning service by a Mexico-based submitter. 

The ZIP file’s accompanying Spanish-language instructions appear to pose as a utility for automating recovery for the content update issue. The instructions prompt the user to run Setup.exe (SHA256 hash: 5ae3838d77c2102766538f783d0a4b4205e7d2cdba4e0ad2ab332dc8ab32fea9) to start the patch installation.

Figure 1. Content of instrucciones.txt

When executed, Setup.exe will load and execute the HijackLoader first-stage inside madBasic_.bpl (SHA256 hash: d6d5ff8e9dc6d2b195a6715280c2f1ba471048a7ce68d256040672b801fda0ea) via DLL search-order hijacking. 

HijackLoader — advertised as a private crypting service, ASMCrypt — is a modular multi-stage loader highly focused on evading detection. The HijackLoader configuration file named maidenhair.cfg (SHA256 hash: 931308cfe733376e19d6cd2401e27f8b2945cec0b9c696aebe7029ea76d45bf6) contains data that the loader leverages to execute the final RemCos payload, which contacts the command-and-control (C2) server at 213.5.130[.]58[:]433.

Following the content update issue, several typosquatting domains impersonating CrowdStrike have been identified. This campaign marks the first observed instance in which a threat actor has capitalized on the Falcon content issue to distribute malicious files targeting LATAM-based CrowdStrike customers.  

Recommendations

CrowdStrike Intelligence recommends that organizations ensure they are communicating with CrowdStrike representatives through official channels and adhere to technical guidance the CrowdStrike support teams have provided.

Falcon LogScale Queries

This Falcon LogScale query detects the activity described in this report:

// Hunting query for indicators (CSA-240835)

case { in("SHA256HashData", values=["931308cfe733376e19d6cd2401e27f8b2945cec0b9c696aebe7029ea76d45bf6", "c44506fe6e1ede5a104008755abf5b6ace51f1a84ad656a2dccc7f2c39c0eca2", "48a3398bbbf24ecd64c27cb2a31e69a6b60e9a69f33fe191bcf5fddbabd9e184", "d6d5ff8e9dc6d2b195a6715280c2f1ba471048a7ce68d256040672b801fda0ea"]); in("RemoteAddressIP4", values=["213.5.130.58"]) } | table([cid, aid, #event_simpleName, ComputerName])

Indicators of Compromise (IOCs)

Table 1. Campaign IOCs

Additional Resources

• For more information, this blog post is being updated regularly: Statement on Falcon Content Update for Windows Hosts.
• Read this message from George Kurtz, CrowdStrike Founder and CEO: To Our Customers and Partners.
• For technical information, see this blog post: Technical Details: Falcon Content Update for Windows Hosts.
• Read another blog post from CrowdStrike Intelligence regarding the Falcon content issue: Falcon Sensor Content Issue from July 19, 2024, Likely Used to Target CrowdStrike Customers.