Malware authors' continued use of stolen certificates isn't all bad news

Posted by   Martijn Grooten on   Jul 10, 2018

A malware campaign has been using code-signing certificates stolen from Taiwanese companies to sign its samples, ESET researcher and regular VB conference speaker Anton Cherepanov writes.

Malware signed with stolen certificates isn't a new phenomenon. Stuxnet famously used stolen certificates, also from Taiwanese companies, and in 2016 Symantec wrote about a malware campaign that used no fewer than nine stolen certificates. A year earlier, IBM's Limor Kessem looked at the phenomenon of code signing being offered as a service in the cybercrime underground.

In this particular case, two malware families were using the stolen certificates: the PLEAD backdoor (analysed by JPCERT/CC last month) and a password stealer that steals passwords from various browsers. Both malware families are linked to the BlackTech cyber espionage group that Trend Micro wrote about last year and whose activities focus particularly on Taiwan.

PLEAD_D-Link_Certificate.pngD-Link was one of the companies whose certificates was stolen. Source: ESET.

In his blog post, Cherepanov lists a number of indicators of compromise, including the serial numbers of the two affected certificates, both of which have now been revoked. This shows another, more positive side to the use of stolen certificates by malware authors: once the certificate theft has been discovered, it does help defenders find the malware more easily.

Something similar occurs with DKIM, which is used to sign emails and which plays an important role in the fight against unwanted and malicious emails. DKIM private keys can also be stolen, but doing so won't give an adversary more than a short-term advantage: once the malicious use of a DKIM key is discovered, which in the case of email often happens quickly and automatically, emails that are signed with with are actually more likely to be blocked.

twitter.png
fb.png
linkedin.png
hackernews.png
reddit.png

 

Latest posts:

Nominations opened for sixth Péter Szőr Award

Virus Bulletin is seeking nominations for the sixth annual Péter Szőr Award.

Haroon Meer and Adrian Sanabria to deliver VB2019 closing keynote

New additions to the VB2019 conference programme include a closing keynote address from Thinkst duo Haroon Meer and Adrian Sanabria and a talk on attacks against payment systems.

Free VB2019 tickets for students

Virus Bulletin is excited to announce that, thanks to generous sponsorship from Google Android, we are able to offer 20 free tickets to students who want to attend VB2019.

VB2018 paper: Lazarus Group: a mahjong game played with different sets of tiles

The Lazarus Group, generally linked to the North Korean government, is one of the most notorious threat groups seen in recent years. At VB2018 ESET researchers Peter Kálnai and Michal Poslušný presented a paper looking at the group's various…

Book your VB2019 ticket now for a chance to win a ticket for BSides London

Virus Bulletin is proud to sponsor this year's BSides London conference, which will take place next week, and we have a number of tickets to give away.

We have placed cookies on your device in order to improve the functionality of this site, as outlined in our cookies policy. However, you may delete and block all cookies from this site and your use of the site will be unaffected. By continuing to browse this site, you are agreeing to Virus Bulletin's use of data as outlined in our privacy policy.