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Archive for the ‘Internet’ Category

Social Networking Abuse – Potent Threat

Thursday, August 20th, 2015

This blog intends to highlight some of the dangers faced by the general public associated with an ever expanding use of social networking sites, all set to grow at an even greater rate post the launch of government initiatives such as the Digital India campaign.

Social networking sites such as Twitter and Facebook provide an efficient interface for communication with multiple people in a user-friendly manner. People are connected to their friends, family and followers in real-time, on-the-go using mobile devices. The ugly side to this increasing use of social networking sites is the potential for controlled, targeted abuse within a very short space of time. Recently the Hindu newspaper reported the abuse of Twitter in the recruitment programme of banned organisations.

Users of social networking sites do not appear to think twice about sharing large amounts of their private Personally Identifiable Information (PII) online. This freely available PII, which includes date of birth, phone number, address, and so on allows malevolent actors to hone their attacks’ penetrative function. In addition, given the speed of transmission, it is possible for attackers to reach a large number of victims very quickly, potentially triggering a mass panic scenario, or spreading malware, or increasing recruitment for banned organisations, etc.

There is at least one documented case of the use of social networks to trigger mass panic in India through the use of doctored images and targeted, threatening messages. In August 2012 thousands of Indians from some North-Eastern states of the nation were made to feel threatened to the extent that they decided to flee in large numbers to their home states from other parts of the country; a grave situation indeed.

The above real-world example provides a stark reminder about the havoc that can be caused when malicious content goes viral, either intentionally or otherwise. Legislation related to IT in many countries provides for monitoring of online content, inclusive of social networking sites, especially given that national security could well be at stake. In the documented case mentioned above, the attack vectors were neutered and some semblance of normality restored only after the offending sites were temporarily blocked and bulk SMS/MMS were banned for a short time as per the provisions in law.

Some images (adapted to suit the article) are courtesy of several sites.

Samir Mody
Senior Manager, K7TCL

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Gone in 60 Seconds: Is the Internet Becoming Volatile?

Friday, August 14th, 2015

This blog intends to inform the general public about the impact on the Internet of an increase in the prevalence of self-destructing messaging services.

Almost everyone of us is so happy with more than one genie at hand; as we own a smartphone, tablet, laptop, etc … and a click of a button or a screen-touch can satisfy our cravings from food to knowledge. Also the communication world is never running short of new stuff popping up now and then with tweets, pokes, chats, likes, posts and so on.

Don’t we enjoy a twist in the movies we watch? One has to wonder if the Internet is the next ‘anterograde amnesia’ victim, where an unforeseen whirl takes over social networking services silently.

On one hand, Hadoop technology is booming to handle the exponential growth of data, and spiders are crawling over the internet to feed search engines. But there is a potential balance created by self-destructing communication methods important enough to discuss, as the number of apps and services providing this functionality are increasing with more number of users everyday. In addition the social networking giants’ competing feature is shifting focus from providing nearly unlimited storage space to providing an expiry time on demand. A silent balance is inching toward creating major chunks of the lost internet.

When communicating confidential information over the internet, there is a jolt in us. We think several times, whether we can trust the internet and its services. And for one reason or another, we compromise ourselves with the communication services we get online.

Now, the privacy jolt is taking a noticeable turn because it seems to give more power to the users like data wiping, evidence shredding, and “suicidal messages”. It is not strange for us to regret sending a wrong file or a message to an unintended recipient, for liking a wrong post or comment by mistake too. But it is also important to note that these auto-timed or customisable self-expiring messages are redefining secretive communication.

This trend seems to cure the privacy fever of social media with email bombs, ephemeral messages, auto-expiring tweets, timed chats, self-deleting pokes and much more; from its suffering to hold itself together with features like ‘recall’ or ‘undo’ a sent email, off the record chats, etc.

Such self-destructing email services promise to destroy their path traversed over the servers and the email itself in a prescribed amount of time. These promises are not new to us as we have been relying for years on strong encryption and secure channels.

There is always more than one solution to a problem. Few apps use temporary hyperlinks. Some provide a one-time password to access the timed webpage. The passwords and the websites are not available after the expiry time. Some store the contents temporarily in servers until the message is delivered to all the intended recipients and delete the contents from the servers and from the recipient’s inbox once the message is read. Some use external apps and browser extensions too.

Some apps face issues like screenshots being taken, accessed via different modes instead of viewing the content via the app, and message ID vulnerability hacks on related sites too. Some apps have already fallen victims to cyber forensic studies as they save the images and videos in hidden folders or rename the files to unknown file extensions; because researchers are ready to spend a number of hours and thousands of dollars for their research. But competitors release newer products with upgraded versions which offer more sophisticated artificially-intelligent communication systems.

Cyber criminals use such service widely to communicate their secrets or threaten victims. Of course anyone can use this service for having a legitimate conversation as well. One need not forget self-expiring attachments are also joining hands with this feature which prevents the messages from being copied, forwarded, edited, printed, or saved.

With competitors focusing on providing the self-destruction feature, the following questions certainly arise:

  • Will the internet become erasable?
  • Will social networking become the most secret communication method going forward?
  • Did we just discover invisible data or communication?
  • Will these mortal messages force cybercrime lexicology to accept its demise?
  • Will the expansion of SMS be changed to Short-lived Messaging Service?
  • Will the cyber crime investigators exclaim: “Eureka! But where did the evidence go?”?

Looks like we just have to wait and watch what surprises the future brings.

Images courtesy of:
cdn-media-1.lifehack.org/wp-content/files/2014/04/7557deec.jpg
blog.ericgoldman.org/wp-content/uploads/2014/08/shutterstock_167170781.jpg

Ayesha Shameena P
Threat Researcher, K7TCL

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Let’s Get Edgewise

Friday, August 7th, 2015

This article intends to inform the general public about ‘Edge’, the newest browser from Microsoft shipped with Windows 10. It sheds some light on what’s new, what’s changed and why Edge was considered necessary.

It has been more than a week since Windows 10 started hitting users’ PCs; it has however been around for a couple of months via the Windows Insider program as a public beta. Reviews on the operating system have been trending in the tech review sites. Opinions in general have been on the positive side for Microsoft’s la(te)st operating system. One of the features that is generating interest is the new browser “Edge” offered in Windows 10.

Microsoft finally bid goodbye to its ageing browser, Internet Explorer (‘IE’). Antiquated design, interoperability issues and security holes riddled IE, warranting a better, modernized browser. Codenamed as project Spartan it finally shaped up as Edge. Microsoft reworked its browser almost from scratch, borrowing bits of goodness from its competitors while being unique in its own way by having a personal assistant or being able to annotate on webpages and share them; most important of all, though, improvements to security were made.

Security was probably one of the main concerns that pushed Microsoft to reimagine its browser design. So from a security perspective, Microsoft has got rid of its ActiveX support, infamous for its security vulnerabilities. Added to the “gone” list were BHOs (Browser Helper Objects, which went on to be synonymic to toolbars) and VBScript support. Over the years support for these three features caused numerous security headaches for Internet Explorer.

Edge would remain sandboxed from the rest of the Operating System, hence attempting to prevent any malicious scripts or code from affecting the OS itself. SmartScreen introduced in IE8 is also a part of the Windows 10 shell and is supported by Edge. This can filter out phishing sites by performing reputation checks and blocking them out. The new rendering engine would greatly eliminate interoperability problems for web developers, thereby allowing them to devote more time to security and stability.

Most security features that had been an opt-in in IE until now have been made mandatory and will always be on and protecting users. Though Edge looks promising it is a bit rough-edged at the moment. Microsoft is in the process of embracing the extensions model like its competitors, Google’s Chrome and Mozilla’s Firefox, which is said to roll out by the end of this year. Once this is done, Edge would be in a better position to handle the internet; at least way better than IE, one would hope.

A word of caution to our readers; while you may be impatient to upgrade your operating systems to Windows 10, beware of a new wave of spam emails doing the rounds. These are bogus emails offering users a free Windows 10 upgrade; even if you are not a Windows 7 or 8 user (free upgrades are given by Microsoft to genuine Windows 7 and 8 users only). These mails mostly come with a malware of the nasty ransomware category. Microsoft states that users will be informed of the upgrade on their screens and not via emails. Kindly refrain from clicking on such fraudulent emails.

Some images (adapted to suit the article) are courtesy of several sites.

Kaarthik RM
Threat Researcher, K7TCL

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Shell Team Six:Zero Day After-Party (Part III)

Monday, February 23rd, 2015

This is the third part of a six-part blog based on the paper submitted by my colleague Gregory and myself on Advanced Persistent Threats (APT), for AVAR 2014.

Continuing from the second part of our paper…

Exploiting Popular Applications

Popular applications such as web browsers, word processors, etc. in an attempt to provide rich functionality, at times fail to handle untrusted data properly. The attackers probe these applications with a variety of mechanisms such as fuzzing, reverse-engineering, study of any stolen code, etc. in order to discover bugs that allow them to execute malicious code without any user interaction.

Lack of buffer boundary checks in the application’s code is exploited, critical memory area is over written to hijack the control flow of the program and  execute the attacker’s shell code.

Likewise, bugs in handling multiple references to the same object have lead to Use-After-Free class of vulnerabilities which after seeding memory areas with malicious code can be exploited to execute the attacker’s shell code.

Data Execution Prevention (DEP) Bypass

DEP is a security feature provided by the operating system to thwart buffer overflow attacks that store and execute malicious code from a non-executable memory location. The OS leverages the No-eXecute technology in modern day CPUs to enforce hardware assisted DEP that prevents memory areas without explicit execute-privilege from executing. Attempts to transfer control to an instruction in a memory page without execute-privilege will generate an access fault, thereby rendering the attack ineffective.

Bypassing the DEP feature in a process involves locating already existing pieces of executable code from process memory space and manipulating them to use attacker controlled data to achieve arbitrary code execution. This is accomplished using one of the following techniques:

  • Return-to-libc
  • Branch Oriented Programming (BOP)
    • Return Oriented Programming (ROP)
    • Jump Oriented Programming (JOP)

Return-to-libc

This evasion technique involves replacing the return address on the call stack with that of an existing routine in a loaded binary. The parameters/arguments that are passed to such routines are controlled by the exploit data strategically placed on the stack.  A system function like WinExec() can be invoked to load and run a malicious component without running non-executable exploit data.


Fig.6: The stack layout when using return-to-libc attack to invoke system() in GNU Linux (32-bit).

Branch Oriented Programming

This bypassing method involves an attacker gaining control of the call stack and executing carefully stitched pieces of executable code called “gadgets”. These gadgets contain one or two instructions which typically end in a return instruction (ROP) or a jump instruction (JOP) and are located in a subroutine within an existing program or a shared library. Chained together, these gadgets allow an attacker to perform arbitrary operations on a machine.

Fig.7: ROP gadget execution sequence based on exploit controlled stack layout

Address Space Layout Randomization (ASLR) Bypass

In order to thwart BOP attacks, the concept of randomizing executable code locations, by randomizing the base address of the loaded binary, on every system reboot was introduced. This security measure known as ASLR made it difficult for the attacker to predict where the required gadget sequence resides in memory. However, APTs have been observed bypassing this protection using the following techniques:

Loading Non-ASLR modules

Dynamic-Link Libraries compiled without the dynamic-base option cannot take advantage of the protection offered by ASLR and as a result, are usually loaded at a fixed memory space. For example, Microsoft’s MSVCR71.DLL shipped with Java Runtime Environment 1.6 is usually loaded at a fixed address in the context of Internet Explorer making it easy to construct the required gadget chain in memory.

Fig.8: An ASLR incompatible version of MSVCR71.dll

DLL Base Address calculation via Memory Address Leakage

This technique involves determining the base address of any loaded ASLR-compatible DLL based on any leaked address of a memory variable or API within that DLL. Based on the address of this known entity, the relative addresses of all the required gadgets can be calculated and a ROP attack constructed.

Attack techniques such as modifying the BSTR length or null termination allows access to memory areas outside the original boundaries, leading to the memory address of known items being revealed to the exploit code. This can then be used to pinpoint the DLL’s location to use ROP gadgets within it. Array() object also has a length component that can be overwritten to leak memory addresses beyond its bounds.

Browser Security Bypass

Leveraging the operating system’s security, popular web browsers run certain parts of their code, JavaScript execution and HTML rendering for example, as a sandboxed background process. This process runs with limited privileges and has restricted access to the file system, network, etc.  A master controller acting as an intermediary interacts with the user and manages these sandboxed processes. By using this master-slave architecture and providing a controlled environment, users are protected from exploit attempts by limiting a shell code’s capability to access host system resources and confining its damage to within the sandbox.

Since these browsers rely on the operating system’s security model, exploiting unpatched kernel vulnerabilities will result in the malicious code escaping its confined environment. The infamous Duqu malware relied on vulnerability (CVE-2011-3402) in the Win32k.sys driver that improperly handles specially crafted True Type Font (TTF) files. This allowed the malware to escape a user-mode sandboxed environment implemented by the Microsoft Word process and compromise the host.

Fig.9: Vulnerable code snippet from win32k.sys that lead to the Duqu TTF exploit

Enhanced Mitigation Experience Toolkit (EMET) Bypass

EMET is a Microsoft tool that provides additional security to commonly-exploited third-party applications such as web browsers, word processors, etc. It extends the operating system’s protection mechanisms to these vulnerable applications and makes exploitation attempts extremely difficult.

The following table lists the protections offered by EMET and known bypassing techniques [4]:

Click here to read the fourth part of this blog

References:
[4] http://bromiumlabs.files.wordpress.com/2014/02/bypassing-emet-4-1.pdf
[5] http://0xdabbad00.com/wp-content/uploads/2013/11/emet_4_1_uncovered.pdf

Lokesh Kumar
K7 Threat Control Lab

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Shell Team Six:Zero Day After-Party (Part II)

Wednesday, February 11th, 2015

This is the second part of a six-part blog based on the paper submitted by my colleague Gregory and myself on Advanced Persistent Threats (APT), for AVAR 2014.

Continuing from the first part of our paper

Initial Compromise

Armed with information obtained from the previous stage, the perpetrators may adopt several techniques to sneak into the organization. Traditional attacks involve actively targeting vulnerable applications and exploiting Internet facing resources like webservers, SQL servers, FTP servers, etc. As log analysis and security around these external resources have caught on, the attackers have had to evolve their tactics in order to be successful.

Infiltration Methodology

The attackers now target the most vulnerable element of any organization – the human. Social engineering tactics are used to entice an individual or a group of users into running code, which will allow the attackers to introduce their malware into the organization’s network. The most commonly used attack techniques are:

  • Spear Phishing
  • Watering Hole

Spear Phishing

Spear phishing involves the attacker compromising a machine by sending a well-crafted email to a targeted user and convincing him/her to:

  • Open an embedded link that points to a website loaded with zero-day exploits, or
  • Open a malicious attachment (EXE, PDF, DOCX etc.)

both of which exploit the rendering application to drop or download, and execute a payload with backdoor capabilities

Watering Hole

 

Watering hole attack involves the attacker placing exploits, possibly zero-day in nature, on a trusted website which is frequented by the users of the organization.  When a targeted user visits the site, the exploit code is automatically invoked and the malware installed on his/her machine.

Case Study

The U.S. Veterans of Foreign Wars’ website was recently compromised to serve a zero-day exploit (CVE-2014-0322). A similar watering hole attack exploiting zero-day vulnerabilities has occurred in the past targeting a specific group of people by compromising the website of the Council for Foreign Relations.

Fig.2 shows publicly available website access logs of users along with their non-routable IP addresses. This information can be used to evaluate the browsing habits of individuals in the company and eventually to execute a watering hole attack.


 
Fig.2: Publicly available map of internal IP addresses and their website logs

Security Bypassing

Email attachments, file downloads, HTTP requests, etc. originating from users undergo rigorous checks at various layers that include:

  • Network/Gateway layer scanners
    • Email/File/URL scanners
    • Sandboxed file analysis
  • Endpoint/Desktop layer scanner
    • Anti-Virus/HIPS/firewall
    • Application security features
    • Operating system security features

Once the human element falls prey to social engineering, and is coaxed into downloading a file/email or visiting an exploit site, the attackers are faced with challenge of defeating a series of network and end point security solutions before conquering the victim’s machine. Listed below are some of the tactics used by the perpetrators to bypass these layers of security.

Attachment Archive File Format Abuse

Discrepancies in the way in which a security product handles a compressed file versus that of an un-archiving application has led to abuse of the popular ZIP file format.  Un-archiving apps identify ZIP file types by scanning the last 64KB of the file for a special magic marker. Security scanners on the other hand, with a need for speed, identify the file type by inspecting only the first few bytes from the beginning of the file.

An attacker abuses this disparity by creating a malicious ZIP file and manipulating its headers by adding junk data at the beginning of the ZIP file. This specially crafted file deceives security scanners into thinking that it is of an unknown type and escapes detection, but un-archiving applications are able to successfully extract the malicious code at the end point.

Fig.3 shows a Proof-of-Concept [2] archive file that is capable of evading security scanners

Fig.3: Crafted ZIP file with NULL data prefixed.

Gateway Sandboxing Bypass

Suspicious files that match certain criteria are typically executed within a sandboxed environment for a short period of time. Depending on their behavior, the files are either blocked from the user or released to him/her.

Attackers can craft malicious files which detect such controlled settings by looking for specific registry keys, in-memory code changes, mouse pointer movement, etc.

For example if the malicious file identifies that it is being executed in a sandboxed environment, it stays idle without performing any activity thereby bypassing this check. The Up-Clicker Trojan [3] attempts to evade sandbox analysis by staying idle and waiting for a mouse click before activating itself.

Fig.4: Code showing Up-Clicker Trojan set to activate on mouse click

Browser Multi-Purpose Internet Mail Extensions (MIME) Sniffing

This attack exploits differences in the way in which security scanners and web browsers identify the content returned by an HTTP server.

Security scanners parse the magic headers available at the beginning of a file returned by the web server, to identify the file type. This means that a specially crafted malicious HTML file containing the magic marker commonly found in a GIF image will be identified by the scanner as an image file, exempted from scanning and let through into the network.

Web browsers on the other hand, depend on the MIME type in the HTTP response header returned by the web server to identify the file type. When this information is absent as is the case of a response from an attacker controlled web server, the web browser resorts to content sniffing to determine the MIME type. So, the same malicious HTML containing the GIF magic marker will now be identified as HTML content by the user’s browser and rendered accurately to execute the exploit code.

Fig.5: Malicious script containing bogus RAR and GIF magic markers.

Click here to read the third part of this blog

References:
[2] http://www.reversinglabs.com/news/vulnerability/reversinglabs-vulnerability-advisories.html
[3] http://www.infosecurity-magazine.com/news/trojan-upclicker-ties-malware-to-the-mouse

Lokesh Kumar
K7 Threat Control Lab

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Shell Team Six:Zero Day After-Party (Part I)

Wednesday, January 21st, 2015

This is the first part of a six-part blog based on the paper submitted by my colleague Gregory and myself on Advanced Persistent Threats (APT), for AVAR 2014. This first part introduces the reader to the different phases of an APT and discusses the methodology, prevention and detection techniques of the initial phase of an attack in detail.

The IT security industry is faced with the challenge of dealing with old invasion tactics that have been reborn in new avatars as Advanced Persistent Threats (APTs). APT attacks are tenacious at pursuing their targets and are played out in stages, possibly over a long period of time. With financial backing from state actors and criminal rings, APTs tend to be compound, sophisticated and difficult to detect. Each facet of the intrusion, in an idealist scenario, may be refined to such an extent that the end goal is achieved without a trace before, during or after the event.

Despite the complexity of these types of attacks, certain parameters always need to be satisfied to deliver the payload and retrieve the expected results, leading to the emergence of an attack pattern which may be placed under the microscope and flagged. These parameters include executing arbitrary code by invoking zero-day exploits for popular software, defeating security measures such as DEP & ASLR, e.g. via heap spray and ROP/JOP chains, exploiting EoP vulnerabilities, establishing remote C&C communication channels to issue commands or to exfiltrate stolen data in encrypted form, etc.

Drawing on evidence from documented real-world case studies, this paper details techniques that assist an assailant during the different phases of an APT, bypassing protection mechanisms like application-sandboxing, EMET, IDS, etc. thus attempting to fly under the defense radar at all times. Equipped with this information, we hope to explore methods of discovering each part of the life-cycle of a targeted attack as it is in progress or in the post mortem, thus reducing their efficacy and impact.

Introduction

“If you know your enemies and know yourself, you will not be imperiled in a hundred battles… if you do not know your enemies nor yourself, you will be imperiled in every single battle.” Sun Tzu

As technologies implemented in organizations are becoming advanced, the threats are rapidly evolving too. Through tenacious and coordinated attacks on one’s infrastructure, APTs are able to infiltrate and overwhelm the organization.

The threat landscape has changed. But the general principles of war remain the same.  Knowing the modus-operandi of your faceless attackers helps one evaluate, and harden one’s security measures, and gear up towards facing the attackers head on.  This paper aims to help you do just that.

APT Life-Cycle

The stages of an APT can broadly be classified as follows:

•   Target reconnaissance
•   Initial compromise
•   Expanding access and strengthening foothold
•   Data exfiltration and cleanup

 

 Target Reconnaissance

The reconnaissance phase of a targeted attack sets the stage for the rest of the threat campaign and therefore involves a high degree of planning. The perpetrators spend significant amounts of time learning about their target, collecting as much information as possible about the human, physical and virtual resources of the organization. The intelligence garnered during this stage not only helps the assailants determine key points of entry into the target network but also empowers them to navigate the victim’s network once inside more effectively & efficiently.

Reconnaissance Methodology

The target’s virtual network is plotted using publicly available resources. These resources include:

•   DNS records
•   WHOIS information
•   Email messages
•   Inadequately protected network logs
•   Misconfigured servers, etc.

The organizational structure is also studied to determine employees and their organizational access levels, using social media, search engines and the target’s own website. Profile intelligence gathered could include potential passwords, personal and official email addresses, whether the user is a regular employee, a SOHO user, or a contractor.

Based on this harvested intelligence the infrastructure needed for the attack will be acquired, the course of action to successfully execute the campaign will be determined & evasion techniques that could be followed during the attack will be planned. New domains may be registered, command and control servers set up, exploits crafted, vulnerable employees identified, custom social engineering schemes plotted for these target employees, malicious files created, etc.
 
Recently, US airport workers from over 75 airports were targeted via malicious emails based on information such as their names, titles, and email addresses that were harvested via publicly-available documents [1].

Fig.1 shows how a simple search engine query can divulge information like emails exchanged between personnel in public forums which may seem innocuous, but can be used to launch a spear phishing attack. Popular mailing lists mask this sensitive information to avoid it from being scraped and abused by bots. Valid users on the other hand are allowed access after solving a simple CAPTCHA.

Fig.1: Search result revealing email addresses and other information about employees of an organization.

Prevention/Detection

Most of the intelligence collected by the assailants during this stage is publicly available and in general doesn’t involve the attackers touching any of the internal systems. Information that was gathered from previous APT campaigns but applicable to the current one could also be reused. This makes detecting an APT during these early stages of the attack challenging.

Usual best security practices such as conducting periodic penetration tests, hardening the applications & the operating systems, etc. are still relevant, but these measures by themselves don’t stand a chance against this adversary.

Organizations should take care to both restrict the amount of information that is flowing outside and be aware of publicly available sensitive information which could potentially be used against them.

Profile Scraper

Automated bots can be used to collect publicly available information on the company, the employees, etc. from popular social networking sites and search engines, etc. The data collected can automatically be analyzed for potential sensitive leaks.

Honey Profiles

Fake profiles at different organizational levels meant to be trip wires can be set up on popular social networking sites and connection attempts and profile hits can be analyzed. This could allow organizations to both recognize if they are being targeted and predict which individual or group of individuals are being targeted.

Click here to read the second part of this blog.

References:
1] http://www.seculert.com/blog/2014/07/extended-apt-campaign-targeted-us-airports.html

Images courtesy of google.com

Lokesh Kumar
Manager, K7 Threat Control Lab

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“I’m not a robot”, Google to reCAPTCHA the Flag

Friday, December 12th, 2014

Over the years, online users have had to identify obscure images, typically worn-out text from old newspapers or street addresses, and type the contents into a box to prove their humanness. CAPTCHA (an acronym for “Completely Automated Public Turing test to tell Computers and Humans Apart”), as this process is called, helped prevent robots gain illegal access to websites, in order to propagate spam (unsolicited messages), for example.

However, these days advanced Artificial Intelligence technology with image recognition can solve CAPTCHA puzzles with astonishing accuracy, a whopping 99.8% according to Google. In an attempt to beat these more advanced bots, Google has recently launched a new API (Application Program Interface) called CAPTCHA reCAPTCHA.

With CAPTCHA reCAPTCHA , users are now directly asked to check a box as shown above. If this step is still insufficient to confirm the user’s humanness, a CAPTCHA is thrown. This CAPTCHA asks the users to match a given image with a set of images, usually animals or birds. Though this approach appears simple, Google claims that advanced risk analysis runs on the backend which monitors the user’s interaction with the CAPTCHA till the very end. This is a welcome change, especially for mobile users who face mild inconvenience in resolving the distorted images.

We hope CAPTCHA reCAPTCHA will be more effective in the fight against the bots created by cyber criminals.

Images courtesy of:

xpda.com
imgur.com

Archana, Content Writer

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SOCK! BASH!! SLAP!! PINCH! Battling Vulnerability Fatigue!

Wednesday, October 15th, 2014

Whilst the ghost of Shellshock still haunts everybody two diametrically opposite vulnerabilities have made the headlines over the past 24 hours or thereabouts:

  1. CVE-2014-4114, a remote code execution vulnerability in the Microsoft OS’s rendering of certain OLE objects, actively exploited in the wild, allegedly by Russian threat actors
  2. CVE-2014-3566, effectively a data leak vulnerability in SSL 3.0 for which a PoC attack to steal secure session cookies has been described by the discoverers of the vulnerability at Google

Let’s discuss CVE-2014-4114 first since its impact is more severe given the remote code execution aspect and the evidence of malicious exploitation in the wild. The good news is that Microsoft has issued the patch for this vulnerability as of yesterday. As members of the Microsoft Active Protections Program (MAPP), we at K7 have also received more information about how the vulnerability can be exploited. We have already secured protection against known bad exploit files, and a heuristic fix is ready, but as an additional paranoid step, if you have the K7 product with firewall installed, it should be possible to add a carefully-configured firewall rule for Microsoft Office OLE rendering applications, e.g. POWERPNT.EXE, EXCEL.EXE and WINWORD.EXE, to prevent them from accessing remote network locations, thus mitigating against the silent download and rendering of malicious files.

Now then, CVE-2014-3566; the Google PoC describes a Man-in-the-Middle attack which can be used to steal a supposedly secure session cookie (but this can be any encrypted data) IF the encryption channel is SSL 3.0 based. Serious as this sounds, CVE-2014-3566 is not as potent as the bash vulnerability suite, and not as valuable as Heartbleed in the grand scheme of things. The reasons for this is that there are several mitigating factors:

  1. The communication has to be via SSL 3.0 which is an antiquated, discredited protocol long since replaced by the more secure TLS. Of course client-side browsers may be duped into believing that the server supports only SSL 3.0, and therefore switch to this protocol
  2. The attacker has to insert himself/herself between the client and the server in order to control the format of the traffic and derive the tasty data byte-by-byte
  3. The encrypted traffic itself, separated into blocks, needs to lend itself to the attack in the sense that certain content deemed interesting to the attacker must be at deterministic locations in the encrypted blocks, with a rinse and repeat function as part of the modus operandi.

At the recently-concluded Virus Bulletin 2014 conference, at which we were Shellshocked for the first time, the managing of vulnerability disclosures was extensively discussed. The above couple of vulnerability disclosures have been suitably managed, minimising the impact on the general public.

Samir Mody
Senior Manager, K7TCL

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https://icann-deal.with.it (Part 3)

Thursday, October 9th, 2014

This is the final part of a three-part blog based on my paper for AVAR 2012 that discusses the security challenges involved in adopting two relatively new technologies, namely, Internet Protocol Version 6 and Internationalized Domain Names.

Continuing from the second part of my paper..

Social Engineering. Malware authors/Spammers/Phishers who now have a larger character set to play with are likely to register domains resembling an original site to trick users into divulging information.

Fig.10 below shows the domain information for baidu.com and an IDN equivalent. Considering that the name servers, the e-mail address used to register the domain, etc, do not match, even security savvy users are likely to find it tricky to validate a URL from such IDNs before visiting it.

Fig.10: whois information on the original baidu.com and the squatted IDN version

Thanks to social networking sites like Facebook, twitter etc., which enable instant sharing of information among millions of users from different backgrounds, uncommon URLs could invoke a click from curious users even if they don’t recognise the character set. Malware campaigns such as these, though short lived, could still cause enough damage globally.

Fig.11: Representative example of an attack based on socially engineered IDNs

Matching Incongruence

URL scanners could focus more on consistency or the lack thereof while dealing with phishing and malware related URLs arriving from IDNs. Language mismatch between the message body of the e-mail and the URL, or the URL and the contents of the page that the URL points to, can be deemed suspicious.

Restrictions may be imposed on visiting IDNs which don’t match a user-defined list of allowed languages. Similarly, domains created by combining visually similar characters from different character sets can also be curbed. Popularly known as a Homograph attack, most common browsers already defend users against such threats. While this protection is only limited to within the browser, it can be extended to protect e-mail, social networking and other layers as well [12].

Fig.12 below shows two domains, one created entirely using the Latin character set and the other using a combination of Latin and Cyrillic character sets. Though both domains visually appear to be similar, their Puny Code representation proves otherwise.

Fig.12: Example of two visually similar domains and their Puny Code representation [13]

Security vendors could also continue existing practices of assigning a poor reputation to domains that originate from certain high-risk countries. Such domains are usually created due to nonexistent or inadequate cyber laws in the host country, which result in malware authors abusing them. Reputation can also be assigned to registrars of IDNs based on their commitment to handling abuse reports, enforcement and verification of registrant details, ease of registering domains in bulk, etc.

A solution to address the e-mail spam problem could involve creating a white list of registered mail servers. The Ipv6whitelist.eu project, for example, works on the assumption that all computers send out spam, unless they have been previously registered on the white list [14]. In addition, since there are few mail servers catering to a significantly large user base, one could argue that e-mail could continue using IPv4, which could breath new life into the practice of IP blacklisting, at least for e-mail spam.

There is a Certainty in Uncertainty

The implications of the transition from IPv4 to IPv6, and the introduction of IDNs, are bound to be of major significance to the Internet infrastructure. These changes engender the continuous growth of the Internet by accommodating an increasing number of inter-connected devices, and variegated foreign languages.

As with any change, given the absence of a crystal ball, the move to these new technologies involves risk.Without doubt spammers, phishers and malware authors, seeking to make a quick buck, will exploit the larger attack surface provided by a vastly increased IP address space and language diversity via IDNs. We in the AV industry must take cognizance of this to determine the security implications and forge robust solutions.

As discussed in this paper, the new technologies will put pressure on current methods to counter spam, phishing and malicious URLs, especially where reputation is of prime importance. Fortunately, AV vendors have generally been able to adapt to the regular inflow of new issues, with new responses for these constantly on the anvil.

The changes about to be witnessed and the solutions proposed are likely to have security companies relying heavily on aggressive heuristics and policy-based restrictions, which could increase the number of false positives. However in corporate environments, rules can be configured to suit the risk appetite of the user in question.

Things are about to get a whole lot more difficult. However, greater vigilance, user education, and as ever, timely security industry data sharing, will help in controlling the fallout. The challenge is indeed a major one, but it is certainly not insurmountable. we.can.deal.with.it

References:
[12] http://en.wikipedia.org/wiki/IDN_homograph_attack#Defending_against_the_attack
[13] Information on http://en.wikipedia.org/wiki/IDN_homograph_attack
[14] Information on http://www.ipv6whitelist.eu

Lokesh Kumar
K7 Threat Control Lab

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Keep e-Phishing at Bay

Friday, September 19th, 2014

A thus far undisclosed, potentially serious security flaw has been discovered on eBay according to BBC News. Hackers were apparently successful in exploiting a weakness on eBay’s website that enabled them to multi-redirect customers, via a landing page listing iPhones, to phishing pages purporting to be those of eBay so as to steal their login credentials.

Unfortunately is it likely that several users would have been duped into surrendering their credentials, thus handing over control of their accounts to the bad guys. However, K7 users would have been protected since one of the redirector URLs was blocked by the malicious URL-blocking feature which has the overall effect of nullifying the multi-step redirector chain and protecting users.

From the user’s side it’s difficult to differentiate between legit redirection and non-legit redirection so this is best left to the site blockers in internet security products such as K7 Total Security.

In addition to that we also found directory listing and outdated plugins (such as JWplayer) on the destination website to which users were being redirected. Based on website fingerprinting, it seems websites hosting the phishing pages were almost certainly compromised by the attackers to hide their tracks.

The phishing pages have now been removed, but the domains are still live and we aren’t sure whether the core vulnerability which allowed the hackers in in the first place has been patched. In other words the webserver may be vulnerable to being hacked once more.

At the time of writing this blog we are unsure whether the cross-site scripting (XSS) flaw exists in other eBay item listings which may or may not be currently in the process of being maliciously exploited. Given the popularity of a site such as eBay, the impact of such an attack can be far reaching and varied; it is possible to leverage redirections to deliver malware via drive-by-download attacks.

The question which pops up is, “Was this just a phishing attack ??” It could have been much much more damaging.

Image courtesy of mashable.com.

Priyal Viroja, Vulnerability Researcher, K7TCL

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