Rewterz Threat Alert – Squirrelwaffle Exploits ProxyLogon and ProxyShell Infect Systems

November 23, 2021

Severity

Medium

Analysis Summary

Squirrelwaffle is a malspam loader that emerged in September, 2021 which utilizes malicious links or Microsoft Office files spread through spam campaigns that trigger and infection chain upon being opened. ProxyLogon and Proxyshell were two exploits used in the attacks.

Vulnerabilities CVE-2021-26855 (ProxyLogon), CVE-2021-34473and CVE-2021-34523 (ProxyShell) were used in the exploitation of the servers. ProxyLogon is a server-side request forgery (SSRF) vulnerability that allows threat actors to access an exchange server by sending a specially crafted web request. The ProxyShell vulnerability on the other hand abused URL normalization of explicit Logon URLs to access the exchange machines. The other PowerShell vulnerability can be used to impersonate a local administrator to run PowerShell commands.

The malicious emails contain malicious Microsoft Excel or Word files which lead to downloading ZIP files on the system and executes the malicious DLL.

Impact

Unauthorized Access
Data Exfiltration
Exposure of Sensitive Data

Indicators of Compromise

Domain Name

aayomsolutions[.]co[.]in
agoryum[.]com
arancal[.]com
constructorachg[.]cl
decinfo[.]com[.]br
dongarza[.]com
grandthum[.]co[.]in

Hostname

aparnashealthfoundation[.]aayom[.]com

IP

108[.]179[.]192[.]18
108[.]179[.]193[.]34
23[.]111[.]163[.]242
24[.]229[.]150[.]54

MD5

d868b389f2f824a32367767a17b397b8

SHA-256

4bcef200fb69f976240e7bc43ab3783dc195eac8b350e610ed2942a78c2ba568

SHA-1

41a0834524ce0df8a18cc94b6a1eba6eebf6f397

URL

http[:]//24[.]229[.]150[.]54[:]995/t4
http[:]//aayomsolutions[.]co[.]in/etiste/quasnam-4966787
http[:]//aparnashealthfoundation[.]aayom[.]com/quasisuscipit/totamet-4966787
http[:]//arancal[.]com/HgLCgCS3m/be[.]html
http[:]//decinfo[.]com[.]br/s4hfZyv7NFEM/y9[.]html
http[:]//grandthum[.]co[.]in/9Z6DH5h5g/be[.]html
http[:]//iperdesk[.]com/JWqj8R2nt/be[.]html
http[:]//omoaye[.]com[.]br/Z0U7Ivtd04b/r[.]html

Remediation

Block all threat indicators at your respective controls.
Search for IOCs in your environment.
Download patches for all the CVEs mentioned above at
https://msrc-blog.microsoft.com/2021/03/05/microsoft-exchange-server-vulnerabilities-mitigations-march-2021/
Use Detection and Protection services like XDRs, SOARs, and EDRs