Evolution of the CookieBomb toolkit

An ongoing, large-scale injection campaign has been raging for the
last 6 months. This campaign utilises a toolkit, dubbed CookieBomb (due
to its signature use of cookies), which is fascinating not only in its
apathy toward a particular platform, but also the code used in the
injections, and way in which it has evolved to escape and evade
traditional AV platforms and structures. This blog will:

  • describe the evolution of not only the raw code involved in these
    attacks, but also the delivery mechanisms with which users are lured to
    infected, or outright malicious, pages
  • implicitly highlight the interaction between, and quid pro quo nature of, major threat-actors within the malware ecosphere
  • describe the use of session Cookies and the etymology of the toolkit name: CookieBomb
  • outline the use of CookieBomb to drive traffic toward EK infrastructure, directly or via TDS systems
  • cover the migration from  BHEK to competing EKs in light of the BHEK author’s arrest
  • detail the point at which the campaign forked into two distinct entities

…(read more)

PHP.net compromised, serving up obfuscated content

The Websense® ThreatSeeker® Intelligence Cloud has alerted us regarding content deployed on the web developer’s web site hxxp://php.net/.

Internet users may know that Google Safe Browsing has also alerted users to a possible infection or compromise of php.net, a site currently ranked 220 on the Alexa ranking system. A member of Google’s staff has posted on a number of forums (examples here and here) to confirm that this is, in fact, a true positive, as confirmed by our telemetry. Members of the same forums quickly compared versions of the script, identifying the following code as appended to at least 4 .js scripts within the hxxp://php.net/ domain:

 

 

The following screen shot shows the decoded obfuscation:

 

When we look at the resulting JavaScript, we can identify a URL in the .uk TLD space:

The iFrame source was hosted on a VPS owned by hxxp://webfusion.co.uk/, which should be applauded for swiftly taking the site down, soon after this compromise came to light. Before the takedown, the URL returned one of two types of content: a basic plugin detection script, or the simple string “not ready”, as shown below:

 

The code was served just once per IP and was dependent upon correct Referer and UA strings.

 

The ultimate goal of this injection was to redirect users to the Magnitude Exploit Kit (MEK), which attempts to exploit Adobe and Java platforms, among others, in order to serve up generic Ransomware.

 

Websense customers were, as always, protected against this type of attack by ACE™, our Advanced Classification Engine

Of the 7 Stages of Advanced Threats, Websense offered protection at the following stages:

  • Redirection stage
  • Exploit Kits stage
  • Command and Control URLs

 

Update (at the time of this blog posting): The malicious code has been removed from hxxp://php.net/.

Massive Russian Cyber-criminal Campaign Targets Business Services, Manufacturing, Government, and Transportation Industries

Websense Security Labs™ researchers have discovered a widespread cybercrime campaign utilizing the Mevade malware that appears to be originating from Russia and Ukraine and primarily targeting the business services, government, manufacturing, and transportation sectors in the US, UK, Canada, and India.

In this post we analyze the malware, command and control characteristics, and attack infrastructure used in this campaign.

 

Executive Summary

Websense research performed on 3rd party feeds indicates that this campaign has infected hundreds of organizations and thousands of computers world-wide and appears to be used for a variety of purposes, including redirecting network traffic and click fraud, as well as search result high-jacking. However, the extensible Mevade malware provides a very capable mechanism for data theft through reverse proxying capabilities. Websense customers are protected against attacks such as this at multiple stages of the attack cycle, including attack infrastructure and C2 protocol.

  • Websense Labs researchers have observed a massive cyber campaign that appears to have originated from Russia and the Ukraine beginning around July 23, 2013, and that continues today
  • Targeted industries include: Business Services, Government, Manufacturing, and Transportation
  • Targeted countries include: USA, United Kingdom, Canada, and India (among others)
  • The malware analysis of Mevade below shows use of a reverse proxy capability (similar to Shylock), indicating a very flexible dropper that is well suited to rerouting network traffic, targeted theft of information, and facilitating lateral movement through target networks by creating a network-level backdoor
  • We have observed the command and control infrastructure, detailed below, hosting malware and exploits such as CVE-2012-4681, dating back to August 2012
  • We have observed links with this campaign’s malware (7C5091177EA375EB3D1A4C4A2BBD5EB07A4CC5CC) are associated with the large spike in Tor (Onion Router) which was presumably providing anonymity for the cyber criminals C&C servers in August 2013
  • The heavy use of attack infrastructure (C2 servers) located in Ukraine and Russia and Mevade malware links this group to a potentially well-financed cyber-crime gang operating out of Kharkov, Ukraine and Russia

Special thanks to Websense Labs Researchers Jack Rasgaitis and Gianluca Giuliani for their contributions to this report.

 

Targeted Industries

 

Targeted Locations vs. Command and Control Infrastructure

 

 

Malware Callbacks

The malware calls back with GET requests of the following example format: 

 

  • http://updsvc.net/updater/3ad219fe94fbcaba3687c5298358998d/2

 

A signature can be built with /updater/[32 random characters]/[1 or 2]

Examples:

 

  • /updater/28d949f1d82631dac4539d5d1ac21d6c/2
  • /updater/5eafaed947ea36a0ccec58e788a77b35/2
  • /updater/389b71b07d4d376a70952a1b1c571d68/2
  • /updater/01e8d75a7a368f854bcef52136985092/2
  • /updater/660c989f210fd7027085731478ab5922/2
  • /updater/fbd1375f6a9049ad9dbd0e0a38be4a8a/2
  • /updater/5122379f40e7431638125d6ee939827c/2
  • /updater/cd9d21a004c3a578ac0da997193315be/2
  • /updater/43028ea498e6ec76f5b69d47f0ede71e/2
  • /updater/5f3f651c20e5bfd5ddab74536ddb3b7b/2
  • /updater/bae58af607a8c88c08b9843aaec0327f/2

 

Domains being used for command and control:

 

  • service-stat.com
  • updservice.net
  • autowinupd.net
  • autoavupd.net
  • service-update.net
  • full-statistic.com
  • service-statistic.com
  • stetsen.no-ip.org
  • autodbupd.net
  • automsupd.net
  • titanium.onedumb.com
  • statuswork.ddns.info
  • fullstatistic.com
  • service-statistic.com
  • autosrvupd.net
  • full-statistic.com
  • fullstatistic.com
  • service-update.net
  • storestatistic.com
  • updsvc.net
  • fullstatistic.com
  • reservestatistic.net
  • srvupd.com
  • automsupd.net
  • stotsin.ignorelist.com
  • autosrvupd.net
  • autosrvupd.net
  • reserve-statistic.com
  • autodbupd.net
  • workstat.hopto.org
  • service-statistic.com
  • full-statistic.com
  • srvupd.com
  • updsvc.net
  • automsupd.net
  • autosrvupd.net
  • assetsstatistic.com
  • assetsstatistic.com
  • assetsstatistic.com
  • srvupd.com
  • updsvc.net
  • reserve-statistic.com
  • reserve-statistic.com
  • autodbupd.net
  • fullstatistic.com
  • reservestatistic.net
  • reserve-statistic.com
  • srvupd.com
  • updsvc.net
  • fullstats-srv.net
  • stats-srv.com
  • fullstats-srv.com
  • statssrv.com
  • reserv-stats.net
  • reserv-stats.com
  • pushstatistics.com
  • stats-upd.net
  • reservstats.com
  • push-statistics.net
  • push-stats.net
  • push-stats.com
  • fullstatistic.com

 

Interestingly, most of the domains above are registered with the following contact email address: gmvjcxkxhs@whoisservices.cn contact info: “Whois Privacy Protection Service|Whois Agent”, which indicates a single service was used to register these domains. A quick search of our domain registration database indicates that over 7,000 domains have been registered using this service. 


The majority of Command and Control related IP addresses can be attributed back to the following ASN:

AS44050

Country: RU

Registration Date: 2007-11-09

Registrar: ripencc

Owner: PIN-AS Petersburg Internet Network LLC

 

Malware Analysis

 

  • Malware sha1=7C5091177EA375EB3D1A4C4A2BBD5EB07A4CC5CC Size=369152
  • Historically seen hosted at: hxxp://service-stat.com/attachments/v4_sl.exe

 

Microsoft first detected this malware as Mevade.A on July 2, 2013.

 

Static Analysis of Malware (SHA1 7C5091177EA375EB3D1A4C4A2BBD5EB07A4CC5CC)

As you can see below, the malware is using an integrated services language based on SQL, called WQL (SQL for Windows Management Interface). Below you can see a snippet of code that queries the target system’s database to learn the security settings.

 

 

Here is the direct WQL query to the Windows Management Interface to learn more about installed AntiVirus.  

 

 

The malware authors were kind enough to leave us a list of AV engines that they were attempting to detect.

 

 

Interestingly, the malware attempts to detect the existence of the “Sandboxie” tool commonly used by researchers to analyze malware. Below is a check executed by the malware for the presence of Sandboxie DLLs.

 

 

Below, we see a direct check executed by the malware to search for Oracle/Sun VirtualBox services.

 

 

AV and Security checks complete, install the malware service…

The malware contains a “Resources” section that is used by the code as shown below.

 

 

This confirms our suspicion that the software we have analyzed so far is a loader program to install the malware service.

 

 

The obfuscated code below is used to confirm that the security checks above executed correctly.

 

Once the security checks have been validated and the resources section properly decoded, the loader attempts to install the malware as a service. Below is the sequence of functions offered by the installer.

 

Interestingly, the buffer below contains references to the “3proxy” open source proxy software that we have previously seen associated with the Shylock/Caphaw malware.

 

 

3proxy is a tiny proxy which can be installed on Windows-based systems (hxxxp://www.3proxy.ru/) .  More information about 3proxy below. 

 

 

Why Embed 3proxy in Malware?

A lightweight proxy such as 3proxy provides functionality in advanced malware to allow attackers to tunnel traffic directly through the malware and directly onto a target network. In these cases, the Proxy is configured as a reverse proxy, with the ability to tunnel through NAT (Network Address Translated) environments to create a connection to the attacker’s infrastructure and initiate a backdoor directly into the target network (in this case, using SSH over port 443). The use of reverse proxies indicates that the cyber-criminals plan to manually scan a network and move laterally towards more critical apps and information (such as databases, critical systems, source-code, and document repositories) than might exist on the original machine that has been compromised. 

Details on Shylock’s use of 3proxy:

 

 

Historical Similarities

IP addresses associated with the Command and Control domains above have been associated with hosting the Java 0-day CVE-2012-4681 in August, 2012.

 

Malware sample associated with the recent spike in Tor (Onion Router) traffic observed in September 2013

 

Zero-Day Attack for Internet Explorer (CVE-2013-3897) Goes High Profile

Websense® Security Labs™ has seen a new zero-day exploit for Internet Explorer (CVE-2013-3897) used in highly targeted, low-volume attacks in Korea, Hong Kong, and the United States, as early as September 18th, 2013. The publication of the vulnerability details (CVE-2013-3897) were shared by Microsoft in advance of today’s patch for the vulnerability that is now available for download. Websense ThreatSeeker® Intelligence Cloud was able to correlate those attacks and create a profile about targeted geographical locations where attacks began as well as targeted industries, which will be described later in this post. In addition, we found the targeted attacks that utilized the exploit for CVE-2013-3897 also included older exploits in their attacks like CVE-2012-4792 for certain targets.

 

Executive Summary

  • Websense ThreatSeeker Intelligence Cloud has seen a new zero-day exploit for Internet Explorer (CVE-2013-3897) used in highly targeted, low-volume attacks in Korea, Hong Kong, and the United States, as early as September 18th, 2013. 
  • Websense
    telemetry indicates that the attack campaign using the same infrastructure
    and the exploit (CVE-2012-4792) began as early as August 23rd 2013 before
    transitioning to CVE-2013-3897 in mid-September
    • A patch has been supplied by Microsoft and is available for download.
    • Microsoft took this opportunity to patch a previous vulnerability for Internet Explorer CVE-2013-3893. The patch for both vulnerabilities can be found at this link: ms13-080.
    • Our ThreatSeeker Intelligence Cloud reported that the attacks targeted primarily financial and heavy industries in Japan and Korea.
    • Our telemetry shows that the actors behind these attacks used their infrastructure to launch older exploits for Internet Explorer, such as CVE-2012-4792, which was first seen at the start of 2013.
    • Websense has protected our customers from the recent Microsoft Internet Explorer CVE-2013-3897 and CVE-2013-3893 exploits observed in the wild by using real-time analytics that have been in place for nearly three years.

     

    Vulnerability Details for CVE-2013-3897

     

    The vulnerability is caused by a “use-after-free” error when processing “CDisplayPointer” objects within mshtml.dll and generically triggered by the “onpropertychange” event handler; the vulnerability could be exploited remotely by attackers to compromise a system via a malicious web page. The specific exploit that has been seen uses heap-spray to allocate some memory that employs an ROP technique around the 0x14141414 address (as confirmed by the Microsoft Security Response Center).

     

    A sample of one of the specific exploit pages that has been spotted in the wild shows Javascript code that appears to target Microsoft Windows XP 32-bit with these languages: Japanese or Korean and Internet Explorer 8.

     


     

    The attacks were served by directly browsing to raw IP addresses and were spotted served by selected IP addresses in the network range of 1.234.31.x/24, which is geolocated in the Republic of Korea. The attack lure pages (starting point of the exploit chain) on that network range share the same URL patterns and they all consist of the URL structure <x.x.x.x>/mii/guy2.html.

     

    We also spotted that a URL with that same structure on the same network range was used to serve an older and disclosed exploit for Internet Explorer CVE-2012-4792 also in a low-volume and targeted way. Those attacks were launched at the end of August this year. Here is a snippet of the page located at hxxp://1.234.31.142/mii/guy2.html. In the case of CVE-2012-4792 in this campaign, it looks like there were no conditional checks for the operating system, browser, and language prior to serving the exploit, which means it was served to the target unconditionally.

     

     

     

       

      Telemetry

       

      Looking at the broader picture and taking into account all the related attacks that we’ve seen served from the IP range 1.234.31.x/24, we found some interesting information that can shed more light on the high-level agenda held by the perpetrators in this campaign. The next pie chart shows the different industries that we saw being targeted with this campaign in the last month. The chart reveals that the interest of the perpetrators in this case is broad as they aim to compromise different type of industries that aren’t necessarily related to each other:

       


       

      Another interesting find is that this attack campaign is global; although, as described earlier, attack pages check whether the operating system’s language is either Japanese or Korean before issuing the CVE-2013-3897 exploit. It looks like the geolocation of targeted entities of Korean or Japanese origin are not just limited and based in those countries. For example, one entity that belongs to the Engineering and Construction industry has been targeted in the U.S. as one of its locations. In addition, as mentioned before, those who use CVE-2012-4792 didn’t employ any conditional checks before issuing the exploit, so that meant the potential targets in that case could be more varied. Indeed, we found that with this campaign, a government entity located in the U.S. was targeted with CVE-2012-4792.The next pie chart shows the popularity of the different targeted geographical locations of this campaign:

       

       

       

       

      Exploit Locations vs. Targets

      Websense telemetry indicates that the CVE-2013-3897 exploit has been hosted on servers in Seoul, South Korea at IP addresses 1.234.31.153, 1.234.31.142 and 1.234.31.154. We have seen this exploit targeting computers located in the United States, Hong Kong, and Seoul, South Korea.

       

      Summary

       

      In this blog, we’ve taken a look at a targeted attack campaign that has been in circulation for the past month. It appears that the perpetrators behind this campaign target entities that belong to different industries over a selected set of geolocations, which reaffirms the notion that these kinds of campaigns operate on a global scale and focus on a variety of industries that are not necessarily related. The perpetrators behind these campaigns are innovative and employ zero-day exploit code, but it also appears that their work is customized for their targets since we witnessed older exploits that have already been patched being used in selected attacks.

       

      Update 10/10/2013 – Websense Researchers have confirmed that the attacks seen from this threat actor beginning August 23rd, 2013 were utilizing the CVE-2012-4792 exploit. The first observed use of CVE-2013-3897 as part of this campaign was on September 18th, 2013.


      Cybercriminals Behind CVE-2013-3893 Launched Attacks Earlier Than Previously Reported; More Widespread

      Websense Security Labs™ Websense ThreatSeeker® Intelligence Cloud has discovered that attacks utilizing the most recent Internet Explorer zero-day (CVE-2013-3893) are more prevalent than previously thought.  In this write up we shall analyze the exploit code and perform analysis on the dropped malicious file.

       

      Executive Summary

      • We have seen the CVE-2013-3893 exploit targeting
        Japanese firms in the financial industry hosted on a Taiwanese IP
        address.
      • Our ThreatSeeker Intelligence Cloud reported a potential victim organization in Taiwan attempting to communicate with the associated malicious command and control server as far back as July 1, 2013. These C&C communications predate the widely-reported first use of this attack infrastructure by more than six weeks, and indicates that the attacks from this threat actor are not just limited to Japan.
      • Commonalities in C&C infrastructure, domain registrations, exploit techniques and malware link this threat actor to the Operation DeputyDog and Hidden Lynx attack crew.
      • This alleged hackers-for-hire crew has committed ongoing attacks against businesses, stealing vital information, allegedly dating back to 2009.
      • Our telemetry indicates that these attacks have enough variations to indicate that different high-profile attack teams may be using the same tool sets.
      • Websense has protected our customers from the CVE-2013-3893 exploit observed in the wild using real-time analytics that have been in place for nearly three years.

       

        A Reminder…

        In our previous post (Up to 70% of PCs Vulnerable to Zero-Day: CVE-2013-3893) we covered a remote code execution vulnerability (CVE-2013-3893) that exists across all versions of Internet Explorer. This vulnerability exploits the way that Internet Explorer accesses an object in memory that has been deleted or not properly allocated, allowing an attacker to execute arbitrary code affecting current users with Internet Explorer.

        An exploit leveraging this vulnerability was first discovered in very targeted attacks located in Japan. First disclosed in a Wepawet security advisory on August 29th, 2013, Microsoft released a security advisory (KB2887505) providing details on the vulnerability and a Fix-It solution on September 17th, 2013. Websense researchers reviewed our third-party telemetry feeds to determine the potential attack surface and risk associated with this exploit, and determined that nearly 70% of Windows-based PCs are vulnerable. While the vulnerability can theoretically affect all versions of Internet Explorer, the exploit is targeting only users of IE8 and IE9 who are running the Windows 7 and XP operating systems.

        The Exploit

        On September 25th, 2013, at 00:39 PST, Websense real-time security analytics stopped an exploit against one of our customers (a major financial institution based in Japan) leveraging CVE-2013-3893 being hosted on a Taiwanese IP address (220.229.238.123). The exploit was hosted at the following URL (hxxp://220.229.238.123/tn/images/index.html). It is worth noting that in addition to specific analytics designed to stop this exploit, three different Websense real-time analytics protected our customers from this threat dating back for more than 3 years.

        Below is a screenshot of the Exploit code for CVE-2013-3893 that is hosted on the Taiwanese IP (220.229.238.123). It is interesting that the JavaScript exploit is not obfuscated and is delivered in clear-text, while the shell code and dropper discussed below are both obfuscated.

         

         

        Screen shot of the exploit’s obfuscated shell-code:

         

         

        We were quickly able to recover the XOR key (9F) and de-obfuscate the shellcode with a clear-text  attack to reveal the dropper file. While the delivery mechanisms are very similar, it is interesting to note that the URI path, IP address and image file names are different than those noted in the analysis of the Operation DeputyDog attacks, as this shell code attempts to drop “./tn/logo.jpg” from the IP address (220.229.238.123).

        Analysis of the JPG file, when XORed with 0x95 reveals an executable titled “runrun.exe” (38db830da02df9cf1e467be0d5d9216b):

         

         

        A clear-text attack on the logo.jpg file revealed that it is actually a Windows executable (when XORed with 0x95) with the following attributes:

        $ time ~/obfuscation/xray.pl logo.jpg 

        Opening file: “logo.jpg”

          94BC: [^95] “runrun.exe”

          782C: [^95] “user32.dll”

          79D6: [^95] “KERNEL32.dll”

          7A14: [^95] “ADVAPI32.dll”

            E0: [^95] “PE”

            4D: [^95] “!This program cannot be run in DOS mode.”

          776C: [^95] “Microsoft Visual C++ Runtime Library”

          7C76: [^95] “GetProcAddress”


        Network Analysis

        The runrun.exe immediately performs a DNS lookup for login.momoshop.org

         

         

        Next, runrun.exe initiates an HTTPS connection handshake to login.momoshop.org (210.17.236.29), which is terminated by the server. For some reason, the client never sends a SYN/ACK to continue the HTTPS handshake. More on this when we finish reversing the malware. 

         

         

        Interestingly, momoshop.org was registered on March 16, 2013, by the registrant listed above. This domain is unusually old (6 months) in the context of the other C&C domains that we have seen associated with the malware and that were registered just days before the attacks.

         

        Telemetry Data

        Websense Labs researchers are currently confirming telemetry from the ThreatSeeker network with possibly compromised Taiwanese hosts communicating to the C&C server (180.150.228.102) associated with malware variants (8aba4b5184072f2a50cbc5ecfe326701 and bd07926c72739bb7121cec8a2863ad87) dating back to July 1st, 2013, indicating that attacks from the threat actor identified in the Operation DeputyDog report may have started earlier than previously thought and may not be limited only to Japan.  More on this soon.

         

        Conclusion

        1. We have seen the CVE-2013-3893 exploit targeting Japanese firms in the financial industry, being hosted on a Taiwanese IP address (hxxp://220.229.238.123/tn/images/index.html) as of September 25th at 00:39 PST.

        2. Websense has three real-time analytics (one has been in place for nearly three years) that blocked the CVE-2013-3893 exploit from compromising customers.

        3. ThreatSeeker Intelligence Cloud reports a potential victim organization in Taiwan attempting to communicate with the malicious C&C server (180.150.228.102) associated with the CVE-2013-3893 exploit as early as July 1st, 2013.

        4. The C&C server above can be associated with the Bit9 compromise. The contact email address 654@123.com was used to register the domain blankchair(dot)com which points to the malicious C&C server (180.150.228.102). The same email address was used to register a C&C server downloadmp3server(dot)servemp3(dot)com (66.153.86.14) associated with the Bit9 attacks.  

        5. Websense Threat Intelligence indicates that the threat actor’s attacks were not limited only to Japan as previously reported. The use of separate IP addresses, domain registrations, and permutations to dropper locations indicates a high degree of segmentation between attacks and different teams using the same tool sets, exploits and C&C infrastructure.

         

        The real-time analytics deployed in ACE (our Advanced Classification Engine) were able to detect and stop the attack above at three stages independent of the zero-day exploit (CVE-2013-3893) for which we had built specific protection. These analytics were able to detect the techniques used to deliver and obfuscate the exploit and malware, protecting our customer from being compromised. This is a great example of how offering protection from multiple stages of an attack can stop even highly targeted, low volume threats with cutting edge exploits.

        Low Volume, High Payoff Attacks Target Financial Services Industries in Asia

        Executive Summary

        • Malicious email found targeting financial institutions in the Middle East, Pakistan, and Nepal.
        • Very low volume and advanced penetration techniques applied aiming for stealthy payoff.
        • Websense®  ThreatScope™ sandboxing reveals the attack most likely seeks monetary gain through the use of a banking Trojan variant.

         

        Details

        A few days ago, researchers from Websense Security Labs™ were reviewing data in the Websense ThreatSeeker® Intelligence Cloud and noticed a very small volume email attack targeting companies dealing with currency transfer/exchange located in Asia. Countries that were affected were the UAE, Pakistan and Nepal, but it’s possible that other countries in the region were also targeted. The email messages were spoofing an email account that belongs to a remittance and currency exchange company. They were sent to recipients from the same company and a few other financial organizations in Asia. Some of the headers reveal they were most likely sent from compromised accounts in India and Pakistan. Websense Cloud Email Security proactively blocked the messages, and the data was stored in the ThreatSeeker Intelligence Cloud for review.

        The messages carried a zip attachment containing an executable that is a variant of the Trojan.Zbot.

         

        So how is this campaign different?

        Normally, we see large-scale attacks sent using the Cutwail spambot, and the intended recipients are varied in location and industry. Frequently, we see these type of attacks sent to spamtrap addresses and even honeypot domains. The volume we see across the Websense ThreatSeeker Intelligence Cloud is tens of thousands or sometimes hundreds of thousands for each “brand” attack. In the small campaign we encountered, we saw about 10 instances and a few single references in non-delivery reports. All of the targets were related to the financial sector, and all were in Asia.

        The small volume attack used plain text email with no attempt to clone the appearance of a known bank/financial organization (as is often done in large-scale attacks). The body of the message is simple and the grammar not very out of the ordinary. The subject is suspicious (notice the redundant zero):

         

        Subject: FW: Urgent Money transfer USD $52,1000

         

         

        The zip attachment contains an executable file named:

        Transfer money.doc.exe:

         

        If you look at the icon, you can see that it’s not the typical fake MS Office or Adobe Reader type of icon that we normally see in large-scale attacks. In this case, it seems like the icon uses obfuscation to get around signature-based detection, not a new technique, but less common in typical large-scale attacks these days.

        The malware itself is a variant of a common Trojan. We will review a few highlights later in the text to show the similarities.

         

        For now, let’s dig deeper into the email headers and see if we can get some additional information about the attack:

        All the messages were being spoofed to appear to be coming from the same address (anonymized to protect customer information):

        xm@custdomain1

        The logs in Websense Cloud Email Security show that the spoofing was identified:

        “The sender address is probably forged since its domain is configured in Hosted Email Security but the sending relay is not associated with that domain”

         

        We had 10 messages, 1 non-delivery receipt (NDR), and one complaint from a recipient thinking custdomain1 was the actual address that sent them malware:

         

         

         

         

        As we can see, the mail relays are all associated with hosting companies across multiple locations. So probably not much help there. When we examine the received lines in the headers, we can see that some have a user IP of 46.37.180.217 both on evirtualservers.net (Germany) and on ukfast.net (UK). However, checking that IP address leads to BurstNET Limited (UK), another hosting/cloud/data center company that has no direct connection to the attacks. A few messages appear to come through mail.altlastravels.com (atlastravels.com is a Travel company in India), which looks suspicious (notice the extra “l” added). Some messages had Anti-Abuse headers added. Let’s see if they give us more info (the user names have been anonymized):

         

         

         

         

        We can see that the attackers might have used a few compromised accounts of companies in India and Pakistan. We can see that one of the messages was also intended for another currency exchange/transfer company in the UAE.

        The intended recipients we see are on custdomain1, custdomain2 (UAE), smartexchange.ae (UAE), mcb.com.pk (Pakistan) and prabhumoneytransfer.com.np (Nepal). All are involved in financial transactions, so the content of the email might appear relevant. In addition, the tool, a banking Trojan, fits the job.

        This attack seems a lot more targeted than what we see from the threat actors that use Zbot in large scale, but the motive seems to be the same: use of common crimeware for monetary gain.

         

        Malicious Attachment Details

        One of the most popular pieces of Crimeware,  the Trojan.Zbot, is frequently used in large-scale email attacks, either as attachments, or using URLs leading to exploit kits that ultimately drop Zbot on the victim’s computer. Zbot can specifically target banking credentials and other personally identifiable information (PII).

        Zbot (Zeus) source code was leaked in 2011, so it’s quite easy for cyber criminals to compile new variants to get around many AV solutions, before they close the detection gap.

        At the time of the attack, the executable was not previously seen in VirusTotal.com. A day later we tested and saw some minimal AV coverage via generic heuristics, 13/47:

        https://www.virustotal.com/en/file/8750c27c58467b1c05e9912ce80ecce524ff3c38/analysis/1378380234/

         

        Here’s a summary of the Websense ThreatScope Analysis Report

         

         

         

         

        The malware is requesting URLs that are already known to be related to Zbot in the past:

         

        If we examine the behavior we can see created Mutexes* on shared memory, which have been associated with Zbot in the past:

        gcc-shmem-tdm2-use_fc_key (successful)

        gcc-shmem-tdm2-sjlj_once (successful)

        gcc-shmem-tdm2-fc_key (successful)

        * Mutex (Mutual Exclusions) are lock mechanisms used by software to control access to shared resources in order to prevent deadlock. They can be used to identify variants of known malware based on commonality. More on the subject can be found in this computer forensics blog on SANS.ORG

         

        The attachment also drops a copy of itself in the user profile directory, and just as before, at the time of the attack, no VT info, a day later some minimal coverage, detection ratio 9/46:

        https://www.virustotal.com/en/file/f0937ba9cb179dfc8075e1b545e6fccb15a79d4bf784382be3d75a049884738f/analysis/1378380235/

         

        Websense Protection

        Since the attack uses email attachments, it corresponds with some of the stages outlined in our white paper describing the 7 stages of Advanced Threats.

        Lures – Websense Cloud Email Security provides proactive protection against email carrying executables or other suspicious attachments, based on multiple analytics: In this case, the built-in AV engine had generic detection, but in addition, the ThreatSeeker Intelligence Cloud would have quarantined the messages even without AV detection, based on several attributes.

        Dropper File – Websense ThreatScope recognizes the malicious behavior of the dropper file, Websense ACE, our Advanced Classification Engine, offers protection against the executable.

        Call Home -ACE blocks the hosts associated with the call home functions.

        Dropped Files – ACE protects against the URL hosts and blocks the files.

        Data Theft – Websense DLP (data loss prevention) tools can detect and stop the exfiltration of sensitive information, like the banking credentials and PII that are targeted by Zbot.

         

         

        Thanks to Victor Chin for helping with the binary analysis.