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    Author Archive - Jay Yaneza (Technical Support)




    In the entry FlashPack Exploit Leads to New Family of Malware, we tackled the Flashpack exploit kit and how it uses three URLs namely (http://{malicious domain}/[a-z]{3}[0-9]{10,12}/loxotrap.php, http://{malicious domain}/[0-9,a-z]{6,10}/load0515p6jse9.php, http://{malicious domain}/[a-z]{3}[0-9]{10,12}/ldcigar.php) as its landing site.

    We monitored the abovementioned URLs and found out that the FlashPack exploit kit is now using free ads to distribute malware such as ZeuS/ZBOT, DOFOIL, and ransomware variants. This technique of using ad networks for malicious intent is called malvertising.

    Based on data from the Trend Micro™ Smart Protection Network™, the North American region has the most number of users who accessed these malicious URLs.

    Tables 1-3. Most affected regions per URL

    Distributing DOFOIL via Ad Networks

    Around the end of August, we observed that the detections for TROJ_DOFOIL (specifically TROJ_DOFOIL.WYTU, TROJ_DOFOIL.WYTV, TROJ_DOFOIL.WYTX, and TROJ_DOFOIL.SM01) took a sudden surge, which peaked last October. This threat is currently active in the wild and is known for its capabilities such as connecting to C&C URLs, dropping files, and detecting sandboxes.

    Read the rest of this entry »

     
    Posted in Bad Sites, Malware |



    We have been continuously monitoring the FlashPack exploit, especially with the recent attack which affected Japanese users. We recently looked at our Smart Protection Network feedback and found in a new development that majority of the infected systems of FlashPack exploit came from the U.S.

    zemot1

    Figure 1. Top infected countries for the FlashPack exploit (based on feedback from September 24-October 22)

    URL Usage and Malware Payload

    We checked the details of the URLs used by the FlashPack exploit and found that the exploit uses three combinations. We broke down the combinations in the table below.

    zemot2

    Figure 2.  Format of the URLs used by the FlashPack exploit

    Based on our analysis, one significant detail is that majority of the sites are employing bulletproof hosting, though some of the said sites have been taken down already. Furthermore, the domain registrations of the discovered sites are new and have been registered only between September and October 2014.

    Given these facts, having a very strong web filter that enforces an existing IT policy of only allowing access to known sites would be ideal as it effectively filters out unknown sites.  At the onset of infection, the URLs used in this attack may not be rated immediately as these are newly created websites and as such may not have been classified or visited yet by a web filter vendor.

    In one of the URLs that was used as a distribution point, the initial file upon its discovery (sha1: 909dc6764355625cb9a98ae45f986439cf3142a6) had little behavioral characteristics as it just launches calc.exe and is generally benign.

    zemot3

    Figure 3. Behavioral characteristics of the initial benign file (sha1: 909dc6764355625cb9a98ae45f986439cf3142a6), seen through sandbox execution in Deep Discovery Analyzer

    The files downloaded from the distribution sites are named this way:   e54 + [0-9,a-f]{10} + [0-9]{10}  + .exe.  Here are other examples:

    e5444ba64330cd1413790308.exe
    e54443e078e78a1413758471.exe
    e5441bf7a34d961413595002.exe
    e54419339d4cf11413583673.exe
    e544185e1ef4571413580257.exe
    e544183b3ccb0e1413579699.exe
    e544174fb9ca431413575931.exe
    e54416fe30fc2b1413574627.exe
    e544168f59c9c51413572853.exe
    e544165de20c9e1413572062.exe
    e544163fdad9d01413571581.exe
    (and so on …)

    Note that the file name seems to be generated by the affected sites. However, after monitoring these sites for a few days, we see that the payload changes and we were lucky enough to observe several files that distributed through web sites. One such sample (sha1: 987d17220ee8936d2dfb58b35a6adc17f7141d50) is detected by Trend Micro as TROJ_DOFOIL.WYTU. This malware has characteristics like sandbox checking for its evasion tactic, and process injection:

    zemot4

    Figure 4. Behavioral characteristics of TROJ_DOFOIL.WYTU, seen through sandbox execution in Deep Discovery Analyzer

    Aside from the behaviors mentioned above, we also did code analysis for TROJ_DOFOIL.WYTU and found the following details:

    1. This malware does not perform the intended routines if the following are seen:

    zemot5

    Figure 5. Screenshot of listed software

    These refer to actual software:

    • v  sbiedll – Sandboxie, a sandbox security software for Windows
    • v  dbghelp – Debug Help Library, commonly used to for debugging when working with portable executable (PE) file format
    • v  qemu – a generic and open source machine emulator and virtualizer
    • v  virtual – commonly used to refer to VirtualBox
    • v  VMware – like VMware Workstation and other similar software from VMware
    • v  Xen – from the Xen Project, an opensource hypervisor

    2. It creates a mutex, which is a hashed computer name +  volume SN

    3. It drops/creates the following files:

    • %Appdata%\{random1}{random2}.exe
    • StartMenu\Programs\Startup\{random1}.lnk

    Where {random1} and {random2} are generated from hashed computer name

    4. Once active, it connects to the following URLs:

    • hxxp://kilopinkad[.]com/bimforum
    • hxxp://bulbushkinho[.]org/bimforum

    It also sends the following via HTTP request:

    &cmd={getload or grab or getproxy}
    &login={computer name hashed}{volume SN}
    &bits={value}
    &file={value}
    &run=ok
    &sel={malware version} –> ffbot
    &ver={malware version} –> 5.1
    &r=

    zemot6

    Figure 6. HTTP request parameters of TROJ_DOFOIL.WYTU

    After a few days, the site changed back to the original benign file (SHA1: 909dc6764355625cb9a98ae45f986439cf3142a6). Note that all file hashes with their detections are mentioned at the bottom of this article.

    As seen above, the exploit kit has the capability to load other malicious software that can be a launch pad of secondary attacks. The initial file that was used (which launched only calc.exe) can be viewed as a preliminary attempt during the first few days of this exploit kit’s discovery.

    Conclusion

    The risk of an exploit kit is that it is designed to serve as a ‘door’ opener of any malicious file: cybercriminals can change the malware payload to any that they wanted.

    We have already seen further evolution of this particular threat. Through the use of  the Trend Micro Smart Protection Network, we are able to examine files, some of which have new reference data that currently refers to an active malware. One example of is TSPY_ZEMOT.

    zemot7

    Figure 7. TSPY_ZMOT malware file

    ZEMOT is a malware family of Trojan downloaders frequently used by other malware, often to stage additional malware payload (secondary infections). It is known to be distributed via exploit kits. Based on our data (starting from October 13), the North American region is the most affected region by TSPY_ZEMOT.

    zemot8

    Figure 8. TSPY_ZMOT distribution according to region

    Trend Micro is closely monitoring this threat for any new developments. Our Smart Protection Network protects users from all threats associated with the FlashPack exploit kit.

    The following are the related hashes for this attack:

    • 987d17220ee8936d2dfb58b35a6adc17f7141d50 (TROJ_DOFOIL.WYTU)
    • 6b944b5a06e1dee2bd64d2a35d5c14b304a5eb35 (TROJ_DOFOIL.WYTU)
    • 41ff7407630e575d2b7544f79e8da3378d367470 (TROJ_DOFOIL.WYTU)
    • 2df93253f1aa7ab6e99660629ff58efeae9acbc3 (TROJ_DOFOIL.WYTU)
    • 12de009d00b5e543c9d0b6542f1b03516b076478  (TSPY_ZEMOT.SMN0)
    • 2e65dea705983a8ae2e9b4eecd42816bf4ef7a3a (TSPY_ZEMOT.SMN0)
    • 8792dc1f6351e103eac4662ad927b00b663ff08f (TROJ_FORUCON.BMC)
     
    Posted in Bad Sites, Exploits, Malware |



    Legitimate services are often used by cybercriminals to try and make their attacks more convincing. Recently, I spotted attacks that used services and platforms like Google Drive and Dropbox in order to look less suspicious to unwary users.

    I received a spammed message like the one shown right below that supposedly came from Gmail itself. It warned me that someone logged into my account from an unknown device. However, all of the links in it pointed to a Google Drive URL:

    Figure 1. Sample spam email

    Even though the email message is similar to a legitimate Gmail message, a careful user will note that the displayed e-mail address and the supposed source address did not match. Further examination of the email’s headers indicates that the email was, in fact, sent via a website’s mail form.

    As I mentioned earlier, all the links provided in the email actually go to an HTML file hosted on Google Drive. This HTML file is used to detect the operating system and browser of the user. For example, this particular code is used to determine what operating system the user is running:

    function nav() {
    var OSName="UnknownOS";
    if (navigator.platform.indexOf("Win")!=-1) OSName="W";
    if (navigator.platform.indexOf("Mac")!=-1) OSName="M";
    if (navigator.platform.indexOf("X11")!=-1) OSName="U";
    if (navigator.platform.indexOf("Linux")!=-1) OSName="L";
    if (/Android/.test(navigator.userAgent)) OSName="A";
    return OSName;

    Note that the above code is comprehensive and considers various platforms: Windows, Mac, Unix, Linux, and even mobile platforms (Android). Further code also differentiates what payloads are delivered based on the user’s browser. This is what the user would see (here, running Firefox):

    Figure 2. Fake plugin download page

    However, while the HTML code can differentiate between different configurations, a relatively limited number of payloads are actually delivered. These are detected as BKDR_PERCS.A.  This backdoor steals email credentials and user names and passwords. It also logs keystrokes as part of its information theft routines. As a backdoor, it can also accept remote commands from the attackers.

    Examining the infection chain in Deep Discovery Advisor makes the infection chain a little clearer:

    Figure 3. Deep Discover Advisor screen (Click to enlarge)

    On systems with Firefox, the backdoor is sent in the form of an XPI file (used by Firefox extensions). This binary file contains the backdoor itself, as well as associated malware components.

    The actual malicious payloads are hosted on Google Drive as well. The attackers upload new files to be used in this attack on a fairly regular basis, although the behavior remains the same. For example, on the first day I saw this, this attack distributed files with the following hashes:

    • 012BCE75BCACDAE0CCCB37B6740A925F769F5547
    • D18C7C42236171C37A6A3B7C1DEE6E0A6381AC4E

    Two days later, the links were changed and now pointed to files with the following hashes:

    • 711AFD18ACCF650F6AEC42F836380EE158D4F8D5
    • A7F8F8A251534867CC9FE56636CFAB26D12C03C4

    Several days after that, the same behavior happened and the new files had the following hashes:

    • 711AFD18ACCF650F6AEC42F836380EE158D4F8D5
    • A7F8F8A251534867CC9FE56636CFAB26D12C03C4

    As these files are located on legitimate services, they are also sent via HTTPS, which helps evade some web filtering techniques. In addition, it used a compromised website’s mailer system and an IPv6 address, which can also evade email reputation services.

    gmailspam_image6

    Figure 4. Screenshot of the email headers of the spam email

    gmailspam_smtp

    Figure 5. Screenshot of the name resolution of the sending email server

    Trend Micro protects users from this spam run by detecting malicious files and blocking all related malicious URLs. We also contacted Google about the malicious files that have been uploaded so they can be removed.

     
    Posted in Malware, Spam | Comments Off



    Last week, in the previous part of this post, we went over the behavior of Control Panel (CPL) malware before the actual infection. In this second part, we go over what happens after the malware has reached a system. (Note: much of this analysis was carried out with Deep Discovery Advisor, so some of the screenshots will have been taken from this product.)

    This particular CPL malware (detected as TROJ_BANLOAD.ZAA) appears to be targeted at Windows 7 users – specifically, those using the 32-bit version. How do we know this? Based on previous research, we know that CPL malware is frequently used as a downloader for other malware. We see this behavior in 32-bit Windows 7:

    Figure 1. Behavior under 32-bit Windows 7
    (Click above image to enlarge)

    However, on other platforms (like 64-bit Windows 7), we do not see that behavior.

    Figure 2. Behavior under 64-bit Windows 7

    So, let’s look into what this malware does when it is run in its “right” target environment.

    It accesses four URLs, two of which are non-malicious and Microsoft-related. One is the Compatibility View list for Internet Explorer 9; the other is the browser icon (favicon.ico) for Bing. Two are potentially malicious, with Deep Discovery Advisor flagging one as malicious.

    Figure 3. URLs accessed by CPL malware

    Let’s look at the first potentially malicious domain. It is a .com domain; the WHOIS records also identify a Spanish man as both the registrant and the technical contact for the domain. It was first registered in 2010.

    All this site does is return a simple text string: “NTFD!”. It’s possible that this may be used for command-and-control, although no definitive evidence either way is present. However, by itself, there’s nothing here that indicates malicious behavior, so it is not flagged as such.

    The other domain is more interesting. It appears that it is a compromised site belonging to an Israeli company – the domain is under the .co.il top-level domain, it is hosted in Israel, and the content clearly belongs to the company as well.

    However, the malware downloaded an executable file directly from this server. While it has a different name – 07-03.exe.exe instead of morph.exe – it has the same hash as the dropped file identified earlier. The file name itself is also intriguing, as if read in a day-month format , it reads “March 7″, which was just days before I actually analyzed this particular attack.

    Once on the system, this particular malware drops multiple copies of itself and proceeds to carry out its information theft routines.

    Figure 4. Analysis of payload
    (Click above image to enlarge)

    From there, the usual information theft routines as discussed in our earlier research proceed, targeting the user’s personal information, as outlined in the threat diagram below. We detect this malware as TSPY_BANKER.ZAA.

    Figure 5. CPL malware threat diagram

    Detection and Prevention

    By providing details on how this attack was able to reach user systems, we hope that this can help others from becoming victims of this threat. Our previous research has indicated that Internet users in Brazil are the most common victims of CPL malware, and that has not changed here.

    Beyond common best practices, this incident allows us to see some possible defenses against attacks like these. For emails, checking the sender IP address is already standard behavior. However, defenses and policies against attachments should be considered – these should be scanned for malicious content, and some potentially risky tile types can be blocked.

    As for the potentially malicious URLs, it may be worth considering to block the download of executable files. In this particular case, doing so would have prevented the download of the main payload by the initial CPL downloader. Failing that, endpoint software should be in place to check the reputation of any downloaded files.

    Trend Micro solutions protect against all aspect of this attack, as well as other similar incidents using CPL malware.

     
    Posted in Malware, Spam | Comments Off



    Recently we’ve discussed how Control Panel (CPL) malware has been spreading in Latin America. In the past, we’ve analyzed in some detail how CPL malware works as well as the overall picture of how this threat spreads. In this post, we shall examine in detail how they spread, and how they relate with other malicious sites and components.

    Recently, while I was checking my spam mailbox, I found one of these messages there. Specifically, I found this email sample:

    Figure 1. Spam message

    This roughly translates to:

    From: {Dear Customer} (delivery-receipt@outlook.com)
    Subject: As requested, the Invoice of Payment is Below
    Message Body:
    Good Morning  Sir/Madam customer,
    As requested, the following is the invoice for payment

    [PDF icon] Click here to download.

    The email address used in this attack may look authentic at first glance, but it is actually just an address from Outlook.com, Microsoft’s free webmail service. In the message itself, there are two highlighted items: the PDF icon, and a link after the PDF icon.

    The PDF icon is actually a hot-link of an image hosted by Google which is a PDF download icon. When clicked, this leads to a fake “access denied” website.

    However, if the user does click on the link, as opposed to the icon, they are directed to a document that is hosted on a Google Drive. From this document, the user is redirected to a malicious page, as seen below:

    Figure 2. Google Drive document

    After more redirections, the user is sent to the URL of a malicious archive. Inside this downloaded archive named Fature.zip one finds the Control Panel malware.

    Figure 3. Malicious archive

    Redirection Details

    As seen, there are actually three malicious sites necessary to get to the malicious file. The overall infection chain is:

    1. Spam message
    2. Google Drive URL
    3. http://{malicious domain #1}/Pdf/Visualizar.php
    4. http://{malicious domain #2}/Fatura.zip

    Both of the mentioned malicious domains above are hosted in Brazil, and use the .br top-level domain.

    Using a Google Drive URL as the initial infection vector was a clever decision, as network traffic with Google will not be found malicious, and URL scanners will frequently whitelist a Google-related URL as well.

    The page at this Google URL is actually an HTML document that uses the META tag to redirect users to the first malicious site, as shown in Figure 2.

    Note that at malicious domain #1, there is also one redirect within the site: the URL from Google only goes to the Pdf directory; the site itself redirects users to the Visualizar.php page.

    Figure 4. Malicious site redirection

    From here, how did it download the malicious payload Fatura.zip? It used HTTP status code redirection, as was used by malicious domain #1:

    Figure 5. HTTP status redirection

    The HTTP Location header field (highlighted above) is provided to the web browser under two circumstances:

    • To ask the browser to load a different page. In this case, the Location header would sent with the HTTP 302 status code, and then would provide a “Moved Temporarily” status. This is what was described above. The user has no choice in the matter, as this is part of the HTTP protocol itself.
    • To provide information about the location of a newly created resource, but this would go with an HTTP status code of 201 or 202.

    We can see how the attacker designed this attack to make it more difficult to block: by using a Google-related URL, it makes blocking these URLs very difficult. Even its misuse of the Google Drive service would be tricky to deal with, since the attacker did not actually use the service to host malicious content, but instead used it as a redirector. The multiple redirections can make detecting the “right” URL to block more difficult if no network monitoring is conducted. (A casual inspection might lead someone to believe that the malicious URL came from Google, which is clearly not the case.)

    In the next part, we will look at how this attack proceeds once it has been installed on an affected system.

     
    Posted in Bad Sites, Malware | Comments Off


     

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