Pierluigi Paganini
June 16, 2013
Security experts at TrendMicro revealed to have detected the RARSTONE RAT studying targeted attacks across Asia (e.g. India, Malaysia, Singapore, and Vietnam) conducted against various companies belonging to different sectors such as telecommunications, energy, governments, media, and others.
The APT campaign has been called Naikon, based on the common user agent strings found in related attacks (NOKIAN95/WEB). RARSTONE was spread with a spear-phishing attacks against the target entities, the messages sent attempted to deceive victims proposing diplomatic discussions in the Asia-Pacific region.
RARSTONE is a Remote Access Tool (RAT) discovered early this year by TrendMicro, it’s characterized by a great affinity with the other RAT know as Plug is and was used in April for phishing campaigns that followed the dramatic attack to the Boston Marathon.
The predecessor PlugX was used last year in various high-profile APT campaigns due the efficiency of the malware thanks its capability to hide its “malicious codes by decrypting and loading a backdoor “executable file” directly into memory, without the need to drop the actual ‘executable file’”.
During further investigation researchers detected a RAT, dubbed BKDR_RARSTONE. A, using the same method of loading the backdoor “file” directly in memory without dropping any other “file”.
Another feature of this backdoor is the implementation of SSL to encrypt communication with C&C and masquerading its traffic.
TrendMicro describes the phishing attack in this way:
“The spear-phishing email contains a malicious document as an attachment, which exploits CVE-2012-0158, a dated vulnerability in Windows common control. This vulnerability was also used in other targeted attacks, most recently the “Safe” campaign that compromised several government agencies, media outlets and other institutions.
When the target opens the attachment, a decoy document is dropped into the system, so as to make the victim think that the decoy document is the file they opened. However, in reality, opening the attachment also triggers the dropping of BKDR_RARSTONE. The malware downloads its backdoor component from a C&C server and loads it directly into memory. This behavior makes RARSTONE difficult to detect using ordinary, file-based scanning technologies.”
The use of RAT is very common for cyber espionage campaigns, one year ago Kaspersky Labs that have identified a new variant of the malware used in Tibet against Uyghur hacktivists, a Turkic ethnic group living in Eastern and Central Asia, that infects OS X machines and that was spread with a consolidated schema for politically motivated APT attack (advanced persistent threat). The used malware was a variant of Gh0st RAT, a well know remote access Trojan, that enables to acquire the total control of the target allowing documents theft and cyber espionage.
Also Syrian Government used similar malware against dissidents were using Skype to communicate, it has used the same channel to spread the backdoor “Xtreme RAT”. The schema of the targeted attacks was simple, after the arrest of some dissidents, the government has used their Skype accounts to spread a malware hidden in a file called MACAddressChanger.exe that was accepted by others activists. The dissidents were confident in the MACAddressChanger usage that they have used i the past to elude the monitoring system of the government.
Xtreme Rat is a malware that belongs to the Remote Access Tool category really simple to retrieve on line at a low price (Full version Price: €100 EUR). To confirm that backdoor has been installed by the Syrian Government is the IP address of the command server that belongs to Syrian Arab Republic — STE (Syrian Telecommunications Establishment).
RARSTONE is considered unique from other RATs due its ability to get installer properties from Uninstall Registry Keys, the malicious agent in fact is able to detect which applications are installed on the infected host that could interfere with its functions and then uninstall them.
According TrenMicro experts the attackers behind Naikon used dynamic DNS domains and used registrars with privacy protection, but researchers are convinced that the attacks are part of a broader espionage campaign.
The suggestion for enterprises, principal targets for this type of attacks, is to adopt a layered approach to security to detect in time anomalous behavior that could reveal an ongoing attack.
Pierluigi Paganini
(Security Affairs – Cyber espionage, RARSTONE)
