After Babar and Bunny, Another Espionage Cartoon: Casper Malware

In March 2014, French newspaper Le Monde revealed that France is suspected by the Communications Security Establishment Canada (CSEC) of having developed and deployed malicious software for espionage purposes. This story was based on presentation slides leaked by Edward Snowden, which were then published by Germany’s Der Spiegel in January 2015.

According to the CSEC presentation, the malicious software in question is called “Babar” by its creators, likely after the famous French cartoon character “Babar The Elephant”. Since then, several malware researchers have begun to work on the enigma that is Babar. Marion Marschalek (Cyphort) struck first, with her report on the “Bunny” malware. Bunny shares some characteristics with the Babar malware described by CSEC. In mid-February, Marion published another report, this time on the actual Babar case, explaining in great detail its spying features. At the same time, Paul Rascagnères (G Data) published a blog post on the similarities between Babar and Bunny, and showed that they were very probably related to the malware described in the CSEC’s slides.

In this blog post, we lift the veil on another piece of software that we believe to have been created by the same organization that is behind Babar and Bunny. This component is called “Casper” by its authors – presumably named after yet another famous cartoon character.

Casper was used against Syrian targets in April 2014, which makes it the most recent malware from this group publicly known at this time. To attack their targets, Casper’s operators used zero-day exploits in Adobe Flash, and these exploits were – surprisingly – hosted on a Syrian governmental website. Casper is a well-developed reconnaissance tool, making extensive efforts to remain unseen on targeted machines. Of particular note are the specific strategies adopted against antimalware software.

Context

In mid-April 2014, Vyacheslav Zakorzhevsky (Kaspersky) observed that the website “jpic.gov.sy” was hosting two Flash zero-day exploits, targeting the vulnerability later labeled CVE-2014-0515. This website was set up in 2011 by the Syrian Justice Ministry apparently to allow Syrian people to ask for reparation for the damage of the civil war. The website is still online and apparently currently clean, although it was defaced in September 2014 by some “hacktivist”.

At the time of the events, Zakorzhevsky could not retrieve the payloads distributed by these Flash zero-days exploits. ESET researchers were able to find two of these payloads, thanks to ESET LiveGrid® threat telemetry systems. The URLs of these payloads and the dates when they were seen correspond to Zakorzhevsky’s description.

In a joint effort with Marion Marschalek, Paul Rascagnères, and researchers from the Computer Incident Response Center Luxemboug (CIRCL), we were recently able to determine that the payloads distributed were very likely developed by the same actors who developed the Babar and Bunny software.

How Does Casper Relate to the Other Cartoons?

Our best chance of establishing that the same developers are behind Bunny, Babar and Casper is to identify unusual code or algorithms shared between these various programs. In our comparison we also take into account the so-called “NBOT” malware (also known as the “TFC” malware), whose link with Babar and Bunny was established by Marion Marschalek in her Babar report. Here is a non-exhaustive list of such shared features we observed:

  • Casper hides its calls to API functions by using a hash calculated from the functions’ names, rather than the names themselves. The hashing algorithm is a combination of rotate-left (ROL) of 7 bits and exclusive-or (XOR) operations. NBOT uses the exact same algorithm for the same purpose, whereas Babar hides its API calls in a similar manner but with a different algorithm.
  • Casper fetches information about the running antivirus in a way similar to Bunny, Babar, and NBOT, namely through the same WMI request. Moreover, all these malwares compute the SHA-256 hash of the first word of the antivirus name, although in Casper it is actually never used.
  • Casper generates delimiters for its HTTP requests by filling a specific format string with the results of calls to the GetTickCount API function. The same code is present in some NBOT samples, as shown in the following array.
  • Casper removes its dropper by executing a Windows command created from the following format string:
  • Casper uses an “ID” value set to “13001”, whereas Babar samples contain an ID of “12075-01”. Also, the malware discovered in 2009 by the CSEC possesses an ID of “08184” (slide 8 of the CSEC slides). This similar format, and the increasing value in decimal, could indicate a familial link.

None of these signs alone is enough to establish a strong link but all the shared features together make us assess with high confidence that Bunny, Babar, NBOT and Casper were all developed by the same organization.

Victimology

According to our telemetry data, all the people targeted during this operation were located in Syria. These targets may have been the visitors of the “jpic.gov.sy” website — Syrian citizens who want to file a complaint. In this case they could have been redirected to the exploits from a legitimate page of this website.

But we were actually unable to determine if this were indeed the case. In other words, it is just as likely that the targets have been redirected to the exploits from another location, for example from a hacked legitimate website or from a link in an email. What is known for sure is that the exploits, the Casper binaries and the C&C component were all hosted on this website’s server.

This leads us to a second hypothesis: the “jpic.gov.sy” website could have been hacked to serve as a storage area. This would have at least two advantages for the attackers: firstly, hosting the files on a Syrian server can make them more easily accessible from Syria, a country whose Internet connection to the outside world has been unstable since the beginning of the civil war, as shown in Google Transparency Report. Secondly, it would mislead attribution efforts by raising suspicion against the Syrian government.

Conclusion

As previously explained, we are confident that the same group developed Bunny, Babar and Casper. The detailed analysis of Babar in the CSEC slides from 2009 indicates this group is not a newcomer to the espionage business. The use of zero-day exploits is another indication that Casper’s operators belong to a powerful organization. Finally, the narrow targeting of people in Syria shows a likely interest in geopolitics.

Nevertheless, we did not find any evidence in Casper itself to point a finger at a specific country. In particular, no signs of French origin, as suggested by CSEC for Babar, were found in the binaries.

Author Joan Calvet, ESET


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s