More Brazil malspam pushing Astaroth (Guildma) in January 2023
Introduction
Tuesday 2023-01-03 and Wednesday 2023-01-04 revealed four Portuguese language emails targetging Brazil. These messages are pushing the same type of Astaroth (Guildma) malware I've seen for the past several months.
2023-01-05 update at 20:24 UTC: list of indicators, malware samples, and packet catpures (pcaps) from two infections related to this diary are now available here.
On an infected Windows host, Astaroth malware is an AutoIt v3 script run by an AutoIt executable. The executable is not inherently malicious on its own. But AutoIt is so closely associated with malware that AutoIt's website has a wiki article noting legitimate AutoIt binaries are often detected as malicious by antivirus vendors (reference).
I've already posted ISC diaries about Astaroth malware in February 2022 and August 2022. Today's diary presents two email templates from recent waves of malspam, and it briefly reviews artifacts from a persistent infection using AutoIt.
Shown above: I should proabably say this is "so hot in Brazil right now."
Show above: Flow chart for recent Astaroth (Guildma) infections.
Malspam Examples
Shown above: Malspam from Tuesday 2023-01-03 pushing Astaroth malware.
Shown above: Malspam from Wednesday 2023-01-04 pushing Astaroth malware.
Post-Infection Artifacts
Astaroth malware infects a vulnerable Windows host through AutoIt script. The malicious file is an AutoIt v3 compiled script made persistent through a Windows shortcut under the Startup Menu --> Programs --> Startup directory. The malicious script is run by a legitimate AutoIt executable.
Shown above: Astaroth malware infection made persistent, early on Wendesday 2023-01-04.
Final Words
The following are links from the four emails I've collected so far in 2023.
Links from first email on Tuesday 2023-01-03:
- hxxp://pka77.biagdum[.]review/X17pHJRhHlUB4/.qHANWxMqBxURxuh3O2/328883/CBM_Ref0770590
Links from second email on Tuesday 2023-01-03:
- hxxp://i5ai2h.azuissu[.]directory/E07sWa0JVF3yJz3/ioJFa1sroWslVs3y7I1/357247/CBM_Ref7732548
Links from first email on Wednesday 2023-01-04:
- hxxp://o6a3e.ulafeohash[.]world/Q13hCFaXNQ64X56/lzXQFOhWzChrNh642S5/93886/Imprimir_DACTES
- hxxp://o6a3e.ulafeohash[.]world/Q13hCFaXNQ64X56/lzXQFOhWzChrNh642S5/8276833/4105_CTe_3360277200093886
- hxxp://o6a3e.ulafeohash[.]world/Q13hCFaXNQ64X56/lzXQFOhWzChrNh642S5/8276833/4105_CTePDF_3360277200093886
Links from second email on Wednesday 2023-01-04:
- hxxp://w1oieg.uripawuy[.]town/V19lKMAuK1WH6/r5KPQJkC5HkWAkxu9E1/22356/Imprimir_DACTES
- hxxp://w1oieg.uripawuy[.]town/V19lKMAuK1WH6/r5KPQJkC5HkWAkxu9E1/5134464/4105_CTe_3360277200022356
- hxxp://w1oieg.uripawuy[.]town/V19lKMAuK1WH6/r5KPQJkC5HkWAkxu9E1/5134464/4105_CTePDF_3360277200022356
These URLs are geo-fenced, so they will not provide malware to an English language Windows host from an IP address based in the United States.
A zip archive containing the four emails is available here. Today's diary is a heads-up for this wave of Astaroth/Guildma activity. I will soon post more technical details about the infection traffic on my blog at www.malware-traffic-analysis.net.
2023-01-05 update at 20:24 UTC: list of indicators, malware samples, and packet catpures (pcaps) from two infections related to this diary are now available here.
---
Brad Duncan
brad [at] malware-traffic-analysis.net
Comments
Anonymous
Dec 3rd 2022
9 months ago
Anonymous
Dec 3rd 2022
9 months ago
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<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
Anonymous
Dec 26th 2022
9 months ago
Anonymous
Dec 26th 2022
9 months ago
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Anonymous
Dec 26th 2022
9 months ago
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Anonymous
Dec 26th 2022
9 months ago
Anonymous
Dec 26th 2022
9 months ago
https://defineprogramming.com/
Dec 26th 2022
9 months ago
distribute malware. Even if the URL listed on the ad shows a legitimate website, subsequent ad traffic can easily lead to a fake page. Different types of malware are distributed in this manner. I've seen IcedID (Bokbot), Gozi/ISFB, and various information stealers distributed through fake software websites that were provided through Google ad traffic. I submitted malicious files from this example to VirusTotal and found a low rate of detection, with some files not showing as malware at all. Additionally, domains associated with this infection frequently change. That might make it hard to detect.
https://clickercounter.org/
https://defineprogramming.com/
Dec 26th 2022
9 months ago
rthrth
Jan 2nd 2023
8 months ago