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    Archive for March, 2014

    There are now less than two weeks left until Microsoft terminates support for the incredibly long-lived Windows XP. Rarely has a tech product lasted as long as XP has – from XP’s launch on  October 25, 2001 to its last Patch Tuesday on April 8, 2014 a total of 12 years, 5 months, and two weeks will have passed. Despite that, as of the month of February, StatCounter data indicated that almost one in five PCs still used Windows XP.

    There has been plenty of concern—and in some quarters, hysteria—over this event. When it would happen has been known for some time. Informed users also know that Windows XP was developed in very different circumstances—the famous Bill Gates trustworthy computing memo was sent after Windows XP had been developed and released to the public.

    The end of support for Windows XP concretely means two things: newly discovered vulnerabilities in Windows XP will not be patched anymore, nor will they be documented and acknowledged by Microsoft. This represents an increase in the risk of using Windows XP. Over time, this risk will increase as more issues are found and exploited –  although it may also fall, as the ever-decreasing numbers of Windows XP users means it will no longer be worthwhile to create exploits for an aging operating system.

    However, managing and mitigating risks is what security is all about. We will continue to provide our customers with the necessary tools to help manage the risks facing Windows XP systems. The most valuable tool in managing these risks is virtual patching/vulnerability shielding; products like Deep Security and OfficeScan with the Intrusion Defense  Firewall (IDF) module  scan and inspect network traffic before they reach the user’s applications, providing an opportunity to protect servers and endpoints from vulnerabilities.

    Another solution can be in hardening the endpoints. Endpoint security software will still protect users, if the security software vendor provides continued support for their products. (Trend Micro will continue to provide support for our endpoint software on Windows XP until 2017.) In addition, locking down these systems may be even more appropriate. For example, Trend Micro Endpoint Application Control can help lock down systems by preventing unwanted and unknown applications and processes from running.

    The underlying point is this: yes, Windows XP’s end of support is something that people should worry about—but it  is something that can be planned and prepared for. The tools and expertise are available for users to help protect their systems and networks as needed. We have prepared a primer titled Managing Your Legacy Systems to go into this topic in more detail.

    Posted in Vulnerabilities | Comments Off on Managing Windows XP’s Risks in a Post-Support World

    GnuTLS is a secure communications library implementing the SSL, TLS, and DTLS protocols. It provides applications a way to use the above protocols without having to create their own cryptographic code. It is aimed to be portable and efficient with a focus on security and interoperability. In many cases, it is used instead of other libraries because GnuTLS is distributed under the GNU Lesser General Public License.

    However, it was found that the GnuTLS X.509 certificate verification code fails to properly handle certain error conditions that may occur during the certificate verification process. While verifying the certificate, GnuTLS would report it as successful verification of the certificate, even though verification should have resulted in a failure. This means that invalid certificates may be accepted as valid,

    What makes this flaw truly problematic is that GnuTLS is used in many applications and software packages, including Exim, Weechat, Mutt, Lynx, CUPS, and gnoMint. It could be used for web applications, e-mail programs, and other code that use the library. Therefore, it’s very difficult to ascertain the number of affected applications. Some of the few operating systems that support GnuTLS include:

    • Red Hat Enterprise Linux Desktop (v. 6)
    • Red Hat Enterprise Linux HPC Node (v. 6)
    • Red Hat Enterprise Linux Server (v. 6)
    • Red Hat Enterprise Linux Server AUS (v. 6.5)
    • Red Hat Enterprise Linux Server EUS (v. 6.5.z)
    • Red Hat Enterprise Linux Workstation (v. 6)
    • Ubuntu 12.10
    • Ubuntu 12.04 LTS
    • Ubuntu 10.04 LTS
    • openSUSE 11.4

    An attacker can use a specially crafted invalid security certificate and it will be accepted as valid by an application (e.g., browser, email client, feed reader, etc.) that uses GnuTLS. This can lead to disclosure of confidential information and may lead to complete control of victim’s system through a combination with another vulnerability.

    A Brief Look at the X.509 Code

    The X.509 protocols rely on a hierarchical trust model. Certification Authorities (CAs) are used to certify entities. Usually, more than one certification authorities exist, and certification authorities may certify other authorities to issue certificates as well. One needs to trust one or more CAs for secure communications. In that case, only the certificates issued by the trusted authorities are accepted.

    The root cause is a simple coding flaw that might have been present in several applications, including Linux OSs, for many years. More specifically, the bug involves GnuTLS’s library functions which are used for processing certificate verification of X.509 certificates.

    The main issue of the bug is the goto statement along with an uninitialized variable. goto is an infamous statement which has been criticized by many security researchers. In this instance, if the goto statement is being executed under certain error conditions, it can short-circuit the verification checks and bypass the certificate authentication process, allowing certificates to be presented as verified.

    In the verify.c function, check_if_ca returns “true” or rather 1, when the certificate is genuine or issued by the certified authority (CA). The return value should be zero if the certificate is not genuine or not issued by a certified authority. Few other functions return a negative value when they fail. In most programming languages, 0 evaluates to “false” and any other [integer] value to “true” . So the function is used by gnutls_x509_crt_verify, which verifies X509 certificates, passes the invalid certificate as genuine.

    In C, the programming error handling return codes are checked through the following:

    1. Return zero for success and non-zero (or less than zero mostly) for failure.
    2. Return code explicitly and check them later (for example, “yes”, “no,” etc.)
    3. Return 1 for success and 0 for failure.

    It appears that for GnuTLS , methods 1 and 3 are used together for return codes.

    For the bug fix, the “goto cleanup;” is replaced with “goto fail;”

    Label fail is defined as under
    result = 0;

    Before the bug fix, the cleanup label is defined as under cleanup:

    gnutls_datum_t cert_signed_data = { NULL, 0 };
    gnutls_datnum_t cert_signature = { NULL, 0 };
    gnutls_x509_crt_t issuer = NULL;
    int issuer_version, result;

    After the bug fix, the cleanup label has been changed as under cleanup:

    gnutls_datum_t cert_signed_data = { NULL, 0 };
    gnutls_datnum_t cert_signature = { NULL, 0 };
    gnutls_x509_crt_t issuer = NULL;
    int issuer_version, result=0;

    A comparison of of the fix can be viewed below:

    Figure 1. Screenshot of corrected return codes taken from Gitorious

    Methods of Attack

    An attacker could exploit this issue in many ways, depending on the usage of the vulnerable library. The bug may be exploited in man-in-the-middle attacks. If a victim tries to log in to a site, the attacker can present his own certificate, pretending to be that site. The fake certificate will pass the verification process and will be presented as an authentic certificate. It will thus appear as normal to the victim while the attacker will be able to intercept confidential data. Attacks like these are highly effective and often difficult to detect.

    An attacker could also host his own web server, with some web application having a fake certificate pretending to be any site of his choice. Through social engineering, he can then exploit this vulnerability.

    Mitigating Attacks 

    GnuTLS developers has issued an advisory regarding this issue. Any application using digital certificate verification libraries with other than latest patched version of GnuTLS are affected by this vulnerability. Users of GnuTLS are advised to upgrade to the following version to address the issue:

    • GnuTLS version (3.2.12 or 3.1.22)

    Users can also apply the patch for GnuTLS 2.12.x. All applications linked to the GnuTLS library must be restarted for the update to take effect.


    Hat tip to Nikos Mavrogiannopoulos of the Red Hat Security Technologies Team for spotting this flaw.

    Posted in Vulnerabilities | Comments Off on A Look at the GnuTLS X.509 Verification Code Flaw

    Malware targeting Word and Excel files has been around for some time, but we recently encountered a new malware family, CRIGENT (also known as “Power Worm”) which brings several new techniques to the table. (We detect these files as W97M_CRIGENT.A and X97M_CRIGENT.A.)

    Most significantly, instead of creating or including executable code, CRIGENT uses the Windows PowerShell to carry out its routines. PowerShell is a powerful interactive shell/scripting tool that is available for all current versions of Windows (and is built-in from Windows 7 onwards); this malware carries out all its behavior via PowerShell scripts. IT administrators that are normally on the lookout for malicious binaries may overlook this, as malware using this technique is not particularly common.

    Arrival and Additional Components

    This particular threat arrives as an infected Word or Excel document, which may be dropped by other malware or downloaded/accessed by users. When opened, right away it downloads two additional components from two well-known online anonymity projects:  the Tor network, and Polipo, a personal web cache/proxy.

    The attacker disguised both what these files were (by changing their file name), and where they are hosted by hiding this information in DNS records. Copies of these files are stored using legitimate cloud file hosts (in this case, Dropbox and OneDrive). The URLs of these files were hidden in DNS records. How was this done?

    He had access to the DNS records of two separate domains, and created one subdomain under each of these domains. However, he did not point the subdomains to any particular IP address at all. Instead, he stored text inside the DNS records and queried specifically for TXT records. (To evade local DNS blocking, he made these queries directly to public Google DNS servers.) The command to do so in Windows would have been:

    • nslookup -querytype=TXT {malicious domain}

    Each of the two queries returned a text string with a URL pointing to a legitimate cloud storage provider. One of these links went to Dropbox, the other to Microsoft’s OneDrive. To someone examining the network traffic without looking at the actual files, all that would have been apparent was a pair of DNS queries to Google’s public DNS servers, and a file downloaded from two well-known cloud services. Neither would be found particularly suspicious.

    Command and Control

    Using the installed Tor and Polipo software, it accesses its command-and-control server. The URL it uses contains two GUIDs, as seen below:

    • {C&C server}/get.php?s=setup&mom={GUID #1}&uid={GUID #2}

    Curiously, if the above website is accessed with missing or incorrect GUIDs, the C&C server delivers the following slightly profane message in German:

    Figure 1. C&C server

    However, if the fields are correct, a PowerShell script (detected as VBS_CRIGENT.LK or VBS_CRIGENT.SM) is downloaded which includes all the code necessary to carry out CRIGENT’s malicious behavior. For starters, the following information about the user’s system is sent back to the C&C server:

    • IP Address
    • Country code
    • Country name
    • Region code
    • Region name
    • City
    • Zipcode
    • Latitude
    • User account privilege
    • OS version
    • OS architecture
    • Domain
    • OS Language
    • Microsoft Office applications
    • Microsoft Office versions

    In addition to the above behavior, the script also communicates with the server at every system startup where it listens for commands. Ports related to Polipo and Tor are also opened.

    Infecting Word and Excel files

    The downloaded PowerShell script also contains the necessary code to infect other Word and Excel documents with the malicious CRIGENT code. To do this, it uses PowerShell scripts to modify registry entries, which lowers the security settings of Microsoft Office.

    Figure 2. Script modifying registry entries

    It then searches for all document files of either Microsoft Word or Microsoft Excel – *.DOC, *.DOCX, *.XLS, and *.XLSX – in all available drives. It also disables the ‘alerts’ and ‘macros’ of the files to be infected, so as not to alert the users.

    Any existing .DOCX and .XLSX files are converted to the previous .DOC and .XLS formats, respectively, with the originals being deleted. A Visual Basic module (which contains the malicious macro) is created and saved together with all the .DOC and .XLS files; opening any of these restarts the infection chain.

    Figure 3. Script searching for Word/Excel files

    Aside from compromising the security of the infected system, CRIGENT also infects documents (which may contain critical information) and may render them useless due to their new “format”. Enterprises and individual users may lose crucial data.

    Detecting CRIGENT

    There are several ways to detect the presence of CRIGENT within a network. For starters, the presence of Polipo and Tor within an internal network should be suspicious. We had earlier discussed how to detect and block Tor traffic; this is something that network administrators should consider looking into to deter CRIGENT and other threats using TOR.

    In addition, it’s worth noting that the file extensions that CRIGENT uses to save infected files as – .DOC and .XLS – are no longer the default file types. The versions of Office from Office 2007 onward use, by default, the .DOCX and .XLSX file extensions, with support for the earlier file formats being kept for legacy and backward compatibility purposes. The presence of large numbers of new files using older formats may be a possible sign of the presence of CRIGENT.

    We noted in our 2014 Security Predictions that cybercriminals will use Tor to hide their activities more deeploy, which is what happened here. They also used PowerShell, a key feature of versions of Windows from Windows 7 onwards, to carry out their routine. That, combined with the use of legitimate cloud storage sites, highlights how cybercriminals want to use legitimate services and features for their attacks.

    Trend Micro protects users from this malware via blocking all related URLs and detecting the malware involved.

    Update as of 2:30 AM PDT, March 28, 2014

    The hashes of some of the files used in this attack are:

    • DE59D4F265599C1931807DF6D506BA11E1DBA2DC
    • FFEF3D961C9729660A0009AFC8A149800B84D8F1

    Just six months after mobile malware and high risk apps reached the one million mark, we have learned that that number has now doubled.

    Figure 1. The number of malicious and high risk apps reaches the 2M mark

    This milestone comes at the heels of the “tenth anniversary” of mobile malware. 2004 saw the first mobile malware—a proof-of-concept (PoC) malware named SYMBOS_CABIR—which infected Nokia phones. But it wasn’t until during the start of the smartphone era that mobile malware exploded onto the threat landscape. From relatively harmless pop-up messages, mobile malware has since evolved to include premium service abuse, information theft, backdoors, and even rootkits.

    And the threats continue to evolve. After hitting the 1M mark, we are now seeing mobile malware veer into pioneer territory. These malware could very well be the bellwether for the kinds of malware we’ll be seeing in the following months.

    Anonymity with TORBOT

    The Onion Router (more commonly known as TOR) is known as one way for users to become “anonymous” online. It’s also known for its connection to underground markets. Cybercriminals are now using TOR to hide their malicious mobile routines. ANDROIDOS_TORBOT.A is the first mobile malware to use TOR to connect to a remote server. Once connected, it performs routines like make phone calls, intercept and read text messages, and send text messages to a specific number. The use of the TOR network makes it more difficult to track down the activity and trace the C&C server.

    Proliferation with DENDROID

    We’ve often discussed how the number of mobile malware keeps increasing at a rapid pace. The creation of a particular remote access Trojan (RAT) mobile malware may soon become a significant contributor to that number.

    ANDROIDOS_DENDROID.HBT can take screenshots, photos, and video and audio recordings. It can also record calls. But what makes DENDROID notable is that it is also peddled as a crimeware tool. DENDROID is being sold in underground markets for US$300 with the promise of easily “Trojanizing” legitimate apps. DENDROID provides an APK binder tool, an APK client, and a background control panel for would-be buyers to repack created apps. Perhaps making it more alarming is that DENDROID was actually found in the Google Play Store.; the malware was able to bypass Google Bouncer and avoid detection.

    Mobile Devices Are Now Miners

    Cybercriminals have also branched out to making miners out of mobile devices. ANDROIDOS_KAGECOIN.HBT has the ability to mine cryptocurrencies like Bitcoin, Dogecoin, and Litecoin. The mining only occurs once the mobile device is charging so the excess usage will not be noticeable. However subtle the routine might try to be, the routine takes a definite toll on the mobile device. Mining for digital currencies requires a lot of processing power that most phones do not have so users will end up with phones with sluggish performance.

    The New Frontier for Mobile Threats

    One thing to note is that the malware discussed in this entry involve topics that are pretty popular within the tech landscape. TOR continues to gain popularity and awareness due to concerns over online privacy. Cryptocurrencies, like Bitcoin and Dogecoin, are fast becoming popular with the public as their monetary values continue to rise (and fall). This only shows that cybercriminals are willing to tap into anything remotely feasible in order to gain new victims.

    With mobile threats reaching the 2 million mark , it’s important that users take the time to secure their devices. Scrutinizing apps, avoiding unknown URLs, and deleting suspicious messages and emails can contribute to a device’s security. Paying close attention to reported software vulnerabilities and flaws—such as the ones involving custom permissions and a system crash vulnerability—is also needed as cybercriminals are wont to exploit these. The Trend Micro Mobile Threat Hub provides helpful information about mobile threats and other security tips for smartphones, tablets and other gadgets.

    Posted in Malware, Mobile | Comments Off on Mobile Malware and High Risk Apps Reach 2M Mark, Go for “Firsts”

    Microsoft has released a security bulletin announcing of a zero-day vulnerability affecting Microsoft Word. Furthermore, the company states that there are “limited, targeted attacks directed at Microsoft Word 2010.” If exploited, this vulnerability (CVE-2014-1761) could allow a remote attacker to execute commands remotely via specially crafted files and email messages.

    Microsoft has also released preliminary details of the vulnerability and the exploit code. The vulnerability is exploited if a user opens an RTF file in Microsoft Word or previews or opens an RTF email message in Microsoft Outlook using Microsoft Word as the email viewer. It should be noted that Microsoft Word is the default email reader for Microsoft Outlook 2007, Microsoft Outlook 2010, and Microsoft Outlook 2013.

    Several workarounds were included in Microsoft’s initial bulletin, including disabling opening of RTF files and enforcing Word to always open said type of file in Protected View. A fixtool has also been made available to help address the vulnerability while Microsoft works on a more permanent solution.

    What’s interesting is that Microsoft Word 2003 is listed as one of the affected software for this particular vulnerability—just a couple of weeks before support for Microsoft Office 2003 ends on April 8th.  We advise users to upgrade to later versions of the software to continue receiving security updates.

    We are currently looking into this vulnerability and will provide further information as appropriate. Trend Micro Deep Security has released a new deep packet inspection (DPI) rule to protect against exploits leveraging this vulnerability:

    • 1005990 – Microsoft Word RTF Remote Code Execution Vulnerability (CVE-2014-1761)

    Update as of April 4, 2014, 3:08 P.M. PDT

    Exploits related to this vulnerability are detected by Trend Micro as the following:



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