Malspam pushing Quasar RAT

Malspam pushing Quasar RAT
Introduction Quasar is a publicly-available Remote Access Tool (RAT) for Windows hosts. Here is a link to the Github page for Quasar RAT. This RAT is occasionally distributed as malware through malicious spam (malspam). On Tuesday 2019-09-24 I found malspam with malware based on Quasar RAT. Today's diary reviews the infection activity. The email Shown above: Screenshot of the email. Shown above: The attachment and extracted Windows executable for Quasar RAT. *Infection traffic* Shown above: Screenshot of the infection traffic filtered in Wireshark. Post-infection forensics Shown above: Quasar RAT artifacts on the infected Windows host Indicators of Compromise (IOCs) The following infection traffic was seen on my infected lab host: 192.3.204[.]194 port 442 - www.tradersbolt[.]com - GET /126/invoice1.exe port 80 - ip-api[.]com - GET /json/ - IP address check (not inherently malicious) 92.99.135[.]246 port 4782 - greatest.ddns[.]net - attempted TCP connections but no response 45.74.60[.]135 port 4782 - greatest.ddns[.]net - Quasar RAT C2 traffic port 80 - puu[.]sh - GET /jMSLc.txt port 443 - puu[.]sh - HTTPS traffic port 80 - icanhazip[.]com - GET / - IP address check (not inherently malicious) port 587 - mail.totallyanonymous[.]com - Encrypted SMTP traffic from Quasar RAT-infected host The following items are malware associated with this infection: SHA256 hash: abc980ebd2463ff522ff090914cc21d02915f643f385ee0ea0af23d51a18e47f File size: 861,270 bytes File name: invoice1.zip File description: Zip attachment from malspam SHA256 hash: edcbbb59405b2bb97269ed5db32a15b57154221adb9504ff828ee367953cccc1 File size: 1,084,928 bytes File name: invoice1.exe File location: hxxps://www.tradersbolt[.]com/126/invoice1.exe File location: C:\Users\[username]\AppData\Roaming\filename.exe File description: Quasar RAT EXE extracted from zip attachment or retreived from link in the malspam SHA256 hash: 065ac3f23800921135b1794706aca86ab59c94ab463c5c17a4d3535bf9aab828 File size: 300,544 bytes File location: C:\Users\[username]\AppData\Local\Temp\4VBTZWE4Ngo6.exe File description: File created when Quasar RAT EXE was executed (1 of 2) SHA256 hash: 389863b056fa0c3d4ebf130103445bc56769824f1e6cecea9c950744b80752b0 File size: 422,139 bytes File location: C:\Users\[username]\AppData\Local\Temp\K8k8zyGhVEbc.exe File description: File created when Quasar RAT EXE was executed (2 of 2) Final words The email, a pcap of the infection traffic, and the associated malware is available here. Brad Duncan brad [at] malware-traffic-analysis.net	Brad 417 Posts ISC Handler Sep 25th 2019
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