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    Archive for June 9th, 2014




    Threats like UPATRE are continuously evolving as seen in the development of the techniques used so as to bypass security solutions. UPATRE malware are known downloaders of information stealers like ZeuS that typically spread via email attachments. We recently spotted several spam runs that use the popular file hosting service Dropbox. These use embedded links lead to the download of UPATRE malware variants. What is noteworthy in these spam attacks is that it is the first instance we saw TROJ_UPATRE being deployed via URL found in an email message.

    In one of the spam samples we saw, it poses as an eFax notification mail with a Dropbox link in the message body.  Once unsuspecting users click on the link, it will redirect to a Dropbox URL, leading to the download of a malicious file detected as TROJ_UPATRE.YYMV. When executed, it downloads a ZBOT variant, detected as TSPY_ZBOT.YYMV, which, in turn, drops a rootkit detected as RTKT_NECURS.MJYE. The NECURS variants are known to disable security solutions on infected systems, causing further infection.

    140606comment01

    Figure 1. Sample of these spam emails

    legit_efax2

    Figure 2. Legitimate copy of email message from eFax

    The other spam sample we saw pretended to be an email with a Dropbox link that came from NatWest Bank containing a supposed NatWest Financial Activity Statement, but is actually a TROJ_UPATRE malware. Similarly, it follows the UPATRE- ZBOT- NECURS infection chain.  Based on our investigation, this spam run also uses names of legitimate companies, such as Lloyds Bank, eFax, Intuit, ADP, BBB, and Skype, among others. We also came across spammed messages with embedded Dropbox links but redirects to Canadian pharmacy websites.

    We have been monitoring this spam campaign since it started last May 23 and began to increase a week later. Dropbox was already informed of this incident as of posting.  We have also notified and submitted the current list of affected accounts that seem to be hosting malware in Dropbox.

    Last April, we reported tax-themed spammed messages that also follow the same infection combination of UPATRE, ZBOT, and NECURS.  Based on our data, UPATRE remains as the top malware distributed via spam from January to May 2014.

    140606comment02

    Figure 2. Top 5 distributed malware via spam mail, Jan-May 2014

    Cybercriminals often go with what’s hot and popular for their social engineering lures. In this case, the bad guys abused legitimate Dropbox links in order to trick users into downloading various malware, which can lead to system infection and information theft.

    Trend Micro protects users from this threat by detecting all spam-related samples and malicious files.

    Special mention to Maydalene Salvador for finding this new spam samples, and to Mark Manahan for analyzing this malware

    Update as of 12:15 AM, June 13, 2014

    A few days after we discovered the UPATRE malware that abuse Dropbox links, we found another spam mail that downloads a malicious file from Dropbox.

    SIB_140612comment01

    Figure 3. Sample of the spam mail leading to a CryptoLocker’s variant, Cryptowall

    Here, the spam mail is disguised as a voice mail and the final payload is a CryptoLocker‘s variant, Cryptowall, detected as TROJ_CRYPWALL.D. TROJ_CRYPWALL.D directly opens a Tor website that asks for payment; previous CryptoLocker has its own GUI for payment. Trend Micro protects users from this threat by detecting all spam-related samples and malicious files.

    With analysis from Maydalene Salvador and Rhena Inocencio

     
    Posted in Malware, Spam | Comments Off


    Jun9
    5:04 am (UTC-7)   |    by

    With the 2014 FIFA World Cup in Brazil about to kick off in less than a week, it should be no surprise that phishing sites have intensified their own spam campaigns targeting Brazilians as well.

    Some of these spam runs are fairly basic, as far as these go. This particular one, for example, tries to lure users with a lottery with a jackpot prize of 5 million Brazilian reais (just short of 2.2 million US dollars).

    Figure 1. Lottery phishing message

    A typical phishing attack like this consists of three stages. First, the user visits the phishing site where their information is collected. In this particular case, the stolen information includes:

    • Credit Card Number
    • CVV code
    • Month and year of card expiry
    • Name of issuing bank
    • Online banking password
    • Owner’s email address

    In the second stage, a PHP file stores all of the captured information in a text file stored on the malicious site.

    Figure 2. PHP code

    In this particular case, the text file is named CCS.TXT. In the third stage, this file is emailed to an address under the control of the attacker.

    Figure 3. Stored information

    We have found other attacks that use similar bait, although they are more obviously tied to the World Cup. Here is an example, which we first saw about a month ago:

    Figure 4. World Cup-related phishing site

    In addition to the usual information stolen in phishing attacks, the persons behind this also targeted two pieces of information that are not commonly stolen:

    • the card’s credit limit
    • the user’s Cadastro de Pessoas Físicas (CPF, or personal identification number)

    The CPF is an 11-digit identification number used to identify taxpayers (both Brazilians and resident aliens) in Brazil. Like credit cards, the CPF has a defined format and algorithm that checks if the number is valid.

    How big are these scams? Through our underground research, we were able to identify the size of the “hoard” of stolen credentials one of the cybercriminals using these attacks possessed. We believe that this particular cybercriminal has approximately 5000 credit cards available to sell at any given time. Some of these cards are identified by their network (i.e., Visa or Mastercard), while others are identified by their issuing bank (Bank of America was explicitly mentioned).

    For stolen e-mail accounts, our cybercriminal has plenty of those too. We identified more than 80,000 accounts whose credentials had been stolen. It is particularly telling that almost 83% of these credentials were for providers with domain names in the .br top-level domain. The most common domains for these stolen credentials are in the table below:

    Table 1. Distribution of stolen e-mail account credentials

    This should not be a surprise, as many of these phishing scams are explicitly targeted at users in Brazil. The first example cited here used the name of the largest payment card operator in Brazil, Cielo. The CPF, as we noted earlier, is something issued only to Brazilians or foreigners who live in the country. As is the case with other scams, spam runs are the favored way to spread these attacks to users.

    We are closely monitoring the threat actors behind some of these attacks, and will release more information in future blog posts.

    The Race to Security hub contains aggregated TrendLabs content on security stories related to major sporting events, including the 2014 FIFA World Cup.

     
    Posted in Bad Sites, Spam | Comments Off


     

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