A new wave of attacks linked to the Codoso ATP Group

Pierluigi Paganini January 26, 2016

According to Palo Alto Networks’ Unit 42 the Chinese APT group Codoso has been targeting organizations in various industries in a new wave of cyber attacks.

The group of experts at Palo Alto Networks Unit 42 have uncovered a new cyber espionage operation conducted by the Chinese AT Codoso  (aka C0d0so0 or Sunshop Group).

The Codoso hacking crew has been around since at least 2010 and targeted organizations in different industries, including the defense, energy, finance, government sectors and also political dissidents and think tanks. The researchers at Palo Alto Networks sustain that the Codoso group’s tactics, techniques, and procedures are more sophisticated compared to other APTs.

Early 2015, researchers from iSIGHT Partners published a detailed report on the cyber espionage campaigns managed by the Codoso group.

Security experts at Invincea and iSIGHT Partners in a joint investigation profiled the Chinese APT group that used two distinct zero-day flaws to compromise Forbes.com website. The intent of the group was to run a watering hole attack by exploiting the zero-day vulnerabilities in Adobe’s Flash Player and Microsoft’s Internet Explorer 9.

Among the objectives of the group was to gain access to computers at several U.S. defense and financial companies by exploiting the watering hole methodology, a technique that could be devastating if attackers had also access to zero-day flaws.

The hackers compromised a part of the Forbes.com’s website that displays to visitors before they’re redirected to articles they’ve clicked on, the segment of the web portal known as Forbes.com’s Thought of the Day is powered by a Flash widget.

Codoso APT forbes thought-of-the-day

The Chinese hackers were able to exploit a zero-day vulnerability to hijack the widget from Nov. 28 to Dec. 1.  In this time frame, the APT group targeted visitors who worked at a few unnamed financial firms and US Defense.

Now experts at Palo Alto Networks discovered a new wave of attacks linked to the Codoso APT group against organizations in the telecommunications, high-tech, legal services, education, and manufacturing industries. The attackers leveraged spear phishing emails and compromised websites used for watering hole attacks.

The new attacks mainly targeted server systems, instead of user endpoints, likely to reuse the same infrastructure for other attacks in the future. Also in this case, the hackers launched spear-phishing attacks and watering hole attacks against the victims.

The researchers analyzed also the C&C infrastructure composed of three domains belonging to the Chinese address space and all resolving to a Hong Kong IP.

“In these newly discovered C0d0s0 attacks, several of the targeted hosts were identified as server systems, instead of user endpoints, suggesting the possibility that these specific targets will be used in future attacks as additional watering holes. Both of the malware variants encoded and compressed the underlying network traffic to bypass any network-based security controls that were implemented,” experts noted.

The attacks leveraged at least on two strains of malware never seen before, but with many similarities with the Derusbi malware used by Comodo hackers in the past.

“The malware variants in question do not appear to belong to any known malware family, although the structure of the network communication does bear a resemblance to the Derusbi malware family, which has shown to be unique to Chinese cyber espionage operators. Past observations of Derusbi in various attack campaigns indicate the version used was compiled specifically for that campaign. Derusbi has had both the client and server variants deployed, using different combinations of configurations and modules. The newly discovered activity is consistent with this procedure, with compile times only a few days prior to the observed attacks” states a blog post from Palo Alto Networks.

In one case the hackers disguised the malware as a serial number generator for AVG AntiVirus, once it infects a system it gathers information on the target and tries to download additional plugins from the C&C server.

Codoso serial number generato -500x389

Another strain of the malware recently used by the Codoso ATP, dubbed PORT 22 variant, is disguised as a DLL file that is side-loaded by a legitimate McAfee application.

“This variant, which appears to be more recent than the HTTP variant, is delivered via the filename of ‘McAltLib.dll’ and is configured to be side-loaded with the legitimate McAfee mcs.exe executable.” continues the post.

The DLL file loaded by the legitimate McAfee application appears to be a newer variant of a DLL used by the Codoso ATP in the attack against Forbes, the researchers also discovered the same unique strings in both samples.

Experts at PaloAlto will continue to monitor the group’s activity because they suspect this may be the beginning of a new wave of cyber-espionage operations.

Pierluigi Paganini

(Security Affairs –  Codoso Chinese ATP, cyber espionage)

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