[SANS ISC] How the “Contact Forms” campaign tricks people, (Thu, Dec 16th)


This diary is based on an infection I started on Monday 2021-12-13 at 21:45 UTC that ran until Tuesday 2021-12-14 at 17:17 UTC.  The infection generated traffic for IcedID (Bokbot), DarkVNC, and Cobalt Strike.  A pcap of the network traffic and the associated malware samples are available here.

“Contact Forms” is a campaign that uses a web site’s contact form to email malicious links disguised as some sort of legal complaint.  We’ve seen this campaign push BazarLoader malware and distribute Sliver, but recently it’s been pushing IcedID (Bokbot).  Most of the time, the Contact Forms campaign uses a “Stolen Images Evidence” theme, with emails stating a supposed violation of the Digital Millennium Copyright Act (DMCA).  Below is an example seen on December 9th, 2021.

Shown above:  Contact form email spoofing someone from slack.com.

A website’s contact form is easy method for cyber criminals to reach an organization.  They can enter any name, email, and message text in these forms to deliver.  With anonymous browsing methods like tor or VPN, criminals can hide their true location when filling out these forms.

In this case, the link is a googleapis URL that abuses Google services to distribute malware.  I checked the link in a web browser, and it was a “Stolen Images Evidence” themed web page.  The page automatically presented an ISO file named Stolen_Images_Evidence.iso.

Shown above:  “Stolen Images Evidence” page sending an ISO file.

ISO files have been used by cyber criminals for years, and the Contact Forms campaign started consistently delivering ISO files from these pages as early as November 30th, 2021.  Prior to that, this campaign almost always sent zip archives.

Shown above:  Stolen_Images_Evidence.iso downloaded on 2021-12-13.

Double-clicking an ISO file on a Windows host will mount the file as a drive, then it will open Windows Explorer to view its contents.  In this example, the double-clicked ISO file appears at F: as a DVD drive, and it contains a Windows shortcut.

Shown above:  Windows Explorer shows the ISO file mounted as a DVD drive at F:.

By default, Windows Explorer does not show hidden files, so we should reveal hidden files from the Explorer menu.

Shown above:  Revealing hidden items in Windows Explorer.

Revealing hidden files, we find a DLL and a JavaScript (.js) file hiding in the ISO.  The Windows shortcut runs both files.  It runs the DLL using regsvr32.exe, and it also runs the .js file separately.

Shown above:  Hidden DLL and JS file, and the Windows shortcut designed to run them both.

Examining the Windows shortcut in a hex editor, we find a Windows user account named lamar that may have been used when creating the shortcut.

Shown above:  Windows user account name lamar seen in the Windows shortcut.

The account name lamar has been consistent in each shortcut I’ve examined from these ISO files since they started appearing from the Contact Forms campaign on 2021-11-30.

Indicators of Compromise (IOCs)

The following are IOCs are from an infection run I started on Monday 2021-12-13 at 21:45 UTC that ran until Tuesday 2021-12-14 at 17:17 UTC.

URL for the “Stolen Images Evidence” page:


Domain called by above googleapis page:

172.67.195[.]237 port 443 – maruadix[.]top – HTTPS traffic

Traffic generated after double clicking Windows shortcut in downloaded ISO file:

Caused by the .js file:

104.21.68[.]138 port 80 – maruadix[.]top – GET /stis1.php

Caused by the DLL (an installer for IcedID):

port 443 – aws.amazon.com – HTTPS traffic (not inherently malicious)
192.236.177[.]53 port 80 – hdgravity[.]com – GET /

IcedID (Bokbot) post-infection traffic:

194.180.174[.]136 port 443 – asrspoe[.]com – HTTPS traffic

DarkVNC activity starting on 2021-12-13 at 23:33 UTC:

88.119.161[.]88 port 8080 – encoded/encrypted TCP traffic

Cobalt Strike activity starting on 2021-12-14 at 06:30 UTC and ending at 11:55 UTC:

149.91.89[.]17 port 80 – 149.91.89[.]17 – GET /soft/musicbee.dll
104.41.145[.]218 port 443 – api.musicbee.getlist.destinycraftpe[.]com – HTTPS traffic

Cobalt Strike activity starting on 2021-12-14 at 15:33 UTC and continued through the end of the pcap at 17:17 UTC:

192.34.109[.]104 port 80 – 192.34.109[.]104 – GET /download/HI1FA3OB3N7D9.dll
192.34.109[.]104 port 443 – bqtconsulting[.]com – HTTPS traffic

SHA256 hash: 0e1fa8cc5697d60664e9bf5fb4ef6af14d63d7f31f0b1565e0ff0e7ce86af735

File size: 1,376,256 bytes
File name: Stolen_Images_Evidence.iso
File description: ISO file downloaded from googleapis page.

SHA256 hash: 5b2751fa6c0c93f8f625375a87c8f235d7b61eb9941633f59cf2ec18352f915a

File size: 2,113 bytes
File name: Stolen_Images_Evidence.lnk
File description: Windows shortcut contained in ISO

SHA256 hash: c7d3cabf68151b9207d6262f3fd739f70f18a736a5a8d04479150f08448bd7bf

File size: 1,164 bytes
File name: kf.js
File description: JS file contained in ISO
Analysis: https://tria.ge/211216-ecnb5sbbe2

SHA256 hash: b71f914f40d146462cafac5f360f816d59366be377268b33d0d4688917950223

File size: 221,184 bytes
File name: data.dll
File description: installer DLL for IcedID contained in ISO
Run method: regsvr32.exe [filename]
Analysis: https://tria.ge/211216-ebwbcsbbd7

SHA256 hash: 0cc2afa847096e322c014f04f54b405902ce2613c555fb6b36fc4f93d53ba2a5

File size: 497,278 bytes
File location: hxxp://hdgravity[.]com/
File description: binary of gzip compressed data retrieved by IcedID installer DLL
File type: gzip compressed data, was “Artwork.txt”, from FAT filesystem (MS-DOS, OS/2, NT), original size modulo 2^32 2063440

SHA256 hash: cfc202b44509f2f607d365858a8218dfdc6b26f8087efcc5e46f4fef9ab53705

File size: 341,898 bytes
File location: C:Users[username]AppDataRoamingTrueLendlicense.dat
File description: data binary used to run persistent IcedID DLL

SHA256 hash: 4fbf01e80561ac1528b50e3a49b7b7bf8139decf62c3653672a545cfec7deee5

File size: 154,624 bytes
File location: C:Users[username]AppDataLocalukudhe3ojfepp.dll
File description: IcedID DLL persistent through scheduled task
Run method: rundll32.exe [filename],DllMain –fi=”[path to license.dat]
Analysis: https://tria.ge/211216-d9t1hsbhcm

SHA256 hash: fba9dd0ebb8d838fa394cda10dca50450d8c0fc6158deff38904072140d64507

File size: 154,624 bytes
File location: hxxp://149.91.89[.]17/soft/musicbee.dll
File location: C:Users[username]AppDataLocalTempoben32.dll
File description: 64-bit DLL for Cobalt Strike retrieved by IcedID-infected host
Run method: regsvr32.exe [filename]
Analysis: https://tria.ge/211214-q5xl3afgf6

SHA256 hash: f9c4a119234df78e1ad71b10fb0bf18622fd5245b72b93e5b71992f20cb9fd2e

File size: 413,696 bytes
File location: hxxp://192.34.109[.]104/download/HI1FA3OB3N7D9.dll
File location: C:Users[username]AppDataLocalTempIhopot2.dll
File description: another 64-bit DLL for Cobalt Strike retrieved by IcedID-infected host
Run method: rundll32.exe [filename],[unknown entry point]
Analysis: https://tria.ge/211214-vw9mgsgbe3

Final words

This and similar IcedID infections have led to Cobalt Strike, which can lead to other malicious activity like ransomware as reported in this real-world example.

A pcap of the network traffic and the associated malware from this infection are available here.

Brad Duncan
brad [at] malware-traffic-analysis.net

(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.

Source: Read More (SANS Internet Storm Center, InfoCON: green)

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