These are quick first looks and trend and threats


Read More >>
Written by the security and AV professionals from team K7, meant for the general audience
Read More >>
These are usually articles that go into internals of a virus or deal with security issues
Read More >>
Senior managers speak on areas of interest to them, inside and outside the industry
Read More >>

Archive for the ‘Security news’ Category

Your Computer Too Can Catch World Cup Fever!

Monday, March 23rd, 2015

The internet is abuzz with live scores, statistics, predictions and match highlights of ICC Cricket World Cup 2015 as it gets closer to the final. A simple “2015 World Cup” keyword search can equip an avid cricket enthusiast with all the latest on the World Cup. Yet, the majority of cricket fans are unaware that the top search results could list malicious websites through the attack vector SEO (Search Engine Optimization) poisoning that cyber criminals employ to rank their websites in the top search engine results for a related keyword search.

A cricket fan should be aware about the risk in accessing an unknown website that is ranked highly in the search result. For example, by building a legitimate-looking website that is in sync with the latest information on the World Cup and incorporating their social engineering expertise the attackers could manipulate search engines to feature their website prominently.  This specially crafted website might carry a link to a malware file download to infect the victim’s computer.

SEO poisoning attacks are subtle, hard to detect by laymen and tend to occur every time a global event happens. This could even serve as an entry point to large organizations. Hence, every internet user is advised to access only known reputed websites for the latest happenings to ensure safe computing.

Bleed Blue!

Images courtesy of:

quoteimg.com
4to40.com

Archana Sangili, Content Writer

If you wish to subscribe to our blog, please add the URL provided below to your blog reader: http://blog.k7computing.com/feed/

Editor of Virus Bulletin Magazine Publishes K7’s Live Conference Presentation Online

Wednesday, March 18th, 2015

In the interest  of sharing VB2014 conference papers and presentations the editor of Virus Bulletin magazine has blogged about Gregory Panakkal’s paper titled “Leaving our ZIP undone: How to Abuse ZIP to Deliver Malware Apps” on VB’s information portal on recent security trends.

This paper explores the ZIP file format, specifically as an APK as handled by the Android OS and details the new malformations that can be imposed on the APK file format to bypass AV engine unarchiving and scanning, whilst keeping the APK valid for the Android OS. This paper also describes the concept of a “chameleon ZIP” that is application specific, and the challenges for the AV engine components that scan content based on the identified package type.

A Chameleon Zip Example

Archana Sangili, Content Writer

If you wish to subscribe to our blog, please add the URL provided below to your blog reader: http://blog.k7computing.com/feed/

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

Friday, March 13th, 2015

This is the fourth 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 third part of our paper…

Security Solutions Bypass

The next layer of defense that an attacker confronts is the end point security provided by third party vendors. Host Intrusion Prevention Systems (HIPS) for example, detect ROP exploitation and prevent shell code execution by injecting their modules into commonly exploited applications and placing hooks at various operating system APIs. However, these inline hooks meant to monitor suspicious activities and detect exploitation attempts are placed under the same privilege as the rest of the code in the process, thereby undermining the security solution’s ability to maintain and intercept all the required APIs.

Hook Hopping

This technique involves the attackers executing standard function prologues of intercepted APIs within self and then transferring control just past the JMP instruction intended to intercept the call.

Fig.10: Control flow depicting bypass of JMP instruction in a hooked API

The DeputyDog campaign [6] which exploited the CVE-2013-0389 vulnerability, employed the above technique to bypass the interception of WinExec() API calls by security software.

Direct SYS Calls

These are a sequence of CPU instructions that transfer control to the kernel directly from the application code instead of using the OS provided user mode APIs.

Payload Delivery via Documents or Sparse Encrypted Fetches

Shell code used as part of the exploitation chain may need to execute a larger payload to establish a backdoor on the machine. To prevent this payload from being detected by security scanners, the attackers can:

  • Embed the payload in popular document formats like PDF, DOC, etc. The shell code when run, locates this payload in the document by scanning for specific magic markers, extracts it and executes it, or
  • Download smaller encrypted chunks of the larger payload stealthily onto the victim’s machine. These chunks are later reassembled and executed on the victim’s machine.

Anti-Virus Bypassing

The attackers use custom cryptors to encrypt their malicious code and attempt to defeat traditional signature based Anti-Virus scanners. At times, these files are digitally signed using trusted stolen certificates to appear legitimate and to circumvent local system policies.

The notorious Stuxnet malware for instance used malicious kernel drivers signed with valid stolen digital certificates to bypass Anti-Virus scanners.

Equipped with information about the security solutions installed in the organization’s end point, these payloads are often tested for detection by the vendor’s security scanner before they are deployed onto the victim’s machine.

Volatile Threats

The attackers execute their malicious payloads directly on the victim’s machine without ever writing the file on the machine’s disk. Traditional security solutions that scan only files on the disk in real-time cannot see these malicious payloads that are directly written and executed in memory. Behavioral analysis systems do not intercept these operations either fearing additional performance overheads.

In the BaneChant APT campaign [7], the shell code downloaded an innocuous XOR encoded binary as the first level payload. This binary in turn downloaded a second level payload which was an executable impersonating an image file meant to bypass security scanners. Once downloaded, this binary was executed directly in memory.

Indicators of Compromise

The initial compromise stage of an APT represents an attacker’s attempts to gain entry into the target organization’s network.  In an environment defended by multiple layers of logging and security, it becomes quite a challenge for an attacker to be successful without leaving behind digital footprints. Provided below are some symptoms that could indicate a compromise in an organization’s network:

Suspicious System Changes

The presence of unauthorized applications that start from uncommon auto-start locations could indicate a compromise. Files names that resemble popular/operating system files like svchost.exe, acrord32.exe, etc. and dwell in unusual locations should also raise suspicion levels.

Fig.11: System file name present in an unusual auto-startup location

Hidden instances of popular applications like Internet Explorer, code-injection attempts into trusted operating system related processes, installation of unauthorized software, loading of driver files without an entry in the Service Control Manager, etc. could also indicate compromise.

Unusual Disk Activity

Exploitation attempts using heap spray techniques tend to use significant amounts of memory.

At times this can lead to high disk activity due to frequent page-file access. Attempts to sweep a user’s profile area for personal or confidential data could also result in increased disk activity, which could indicate compromise.

Compromised Security Components

Partially enabled security features or completely disabled security solutions on endpoints, even for a brief period of time, could indicate that something is wrong.

Loading of Unsigned Drivers in x64 Systems

x64-based Microsoft Windows verifies and allows only digitally signed driver binaries to load during system boot-up. Unsigned malware that want to load early on during the boot process will have to disable this verification process.

Boot kits for instance, tend to bypass the driver signing policy by making persistent system wide changes. Successful loading of a custom unsigned “test” driver on a machine infected with such a boot kit could indicate a compromise.

Fig.12: Windows alerting on loading an unsigned driver

Prevention/Detection

Mock Phishes

Since human behaviour is manipulated to the attacker’s advantage during this stage of an APT, training programs should be conducted at regular intervals to educate the users on the latest intrusion techniques. These programs should aim at explaining the importance of security along with adequate examples, as well as changing user behaviour such that they follow security policies correctly.

Pen test emails mimicking a spear phishing attack could be used to improve the employees’ resilience towards such attacks [8].

Virtualization

Email applications and web browsers could be run in a virtualized environment that is automatically reverted during startup.


Malicious email attachments and drive by downloads would be contained within this environment and reboot resilient code would not survive a revert-to-clean-snapshot assuming that the malware cannot escape the guest VM and infect the host.

Intent to View

Suspicious or unknown email attachments should explicitly be stripped by security solutions.

These attachments should be released to a user only if he/she explicitly requests them.

Detecting Bypassing Attempts

Evasion techniques such as hook-hopping can be identified by breaking some basic assumptions made by the attacker. The security solution can replace the random number of instructions from the function prologue with its own code sequence. This way, shell code that attempts to bypass the initial JMP instruction would still land on the code sequence controlled by the security solution.

Few security solutions use multiple int 0×3 instructions past the initial JMP instruction to trigger a debug exception when executed, breaking the flow of execution.

Hook bypass attempts using direct system calls from user-mode processes can be flagged using a kernel module, if this user-mode to kernel-mode transition does not originate from the native layer.

References:

[6] http://www.fireeye.com/blog/technical/cyber-exploits/2013/09/operation-deputydog-part-2-zero-day-exploit-analysis-cve-2013-3893.html
[7] http://www.fireeye.com/blog/technical/malware-research/2013/04/trojan-apt-banechant-in-memory-trojan-that-observes-for-multiple-mouse-clicks.html
[8] http://phishme.com/product-services/what-is-phishme

Lokesh Kumar
K7 Threat Control Lab

If you wish to subscribe to our blog, please add the URL provided below to your blog reader:
http://blog.k7computing.com/feed/

Women Can Say “No” to Cyberbullying

Friday, March 6th, 2015

This is the second part of the blog series on women’s cyber safety, discussing cyberbullying and describing the consequences of cyberbullying in one’s life, continuing from the first part which covered guidelines to women on social networking, the possible risks associated with it and a few precautionary steps to take.

We witness that women across different age groups have been increasingly trolled, bullied, and harassed on the internet based on the personal information visible on their social networking profiles. This trend is now at an all-time high.

Cyberbullying generally involves intimidating or harassing someone via online posts, emails or SMS. This includes activities such as posting hateful or unpleasant comments on one’s online profile, spreading rumors and/or inappropriate personal images through email or SMS to damage one’s reputation. Compared to traditional bullying, cyberbullying is open to an anonymous, or even unknown, person since one’s personal information is primarily posted as “public” on a social networking site. The aggressor remains anonymous and the victim can be taunted anytime , anywhere.


Women on the internet are at a higher risk of encountering cyberbullies at some point during their internet experience. As victims they have a tough time coping with the antagonizing behavior towards them and recovering from the resultant low spirits. This leaves many women hurt, humiliated, depressed and in some extreme cases it has led to taking one’s own life.

Women should be acutely aware that the information shared on the internet is open, free for public viewing and stays forever. As discussed in the previous blog, internet users in India can register a complaint against such cyberbullying issues at Computer Emergency Response Team (CERT).

Let the kids and the teens around you be informed about cyberbullying and its impact on life. To reiterate what was mentioned in the first part of this blog series here are some tips to educate teens and kids on how to avoid falling prey to offenders:

  1. Never share your phone number or email address with strangers or on online public forums.
  2. Refrain from sharing any personal information such as your birthday, where you live, etc on the internet.
  3. Never open or respond to messages from unknown/unauthorized users.
  4. Carefully adjust privacy settings to prevent strangers from contacting you.
  5. Never add strangers to your contacts or friends lists.
  6. Seek immediate help from the trusted people to help solve your cyberbullying problems.

to be continued…

Images courtesy of:

walmsley.bolton.sch.uk/files/images/cyber-bullying-finalcolor.png
bullyinglte.files.wordpress.com/2014/12/cyberbullying.png

Archana Sangili, Content Writer
V.Dhanalakshmi, Senior Threat Researcher, K7TCL

If you wish to subscribe to our blog, please add the URL provided below to your blog reader: http://blog.k7computing.com/feed/

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

If you wish to subscribe to our blog, please add the URL provided below to your blog reader:
http://blog.k7computing.com/feed/

Ladies, Savor Social Networking Safely

Tuesday, February 17th, 2015

As women, we believe it is important to share a blog series, focusing specifically on women’s cyber safety while they use the internet for social and commercial activities, highlighting the dangers of using this medium and providing tips to ensure online safety. This is the first part of the three-part blog series guiding women on social networking and the possible risks associated, providing a few precautionary steps to follow, though not exhaustive.

The internet to the modern women is akin to the purse she carries, indispensable. She uses the internet to interact with friends and family, shop and bank, in that order. A recent survey by comScore revealed that women dominate the usage of social networking sites and wield the social networking portals as an empowering tool to connect across boundaries and to successfully build e-commerce businesses.

Unfortunately the freedom of the internet also helps cyber criminals and online miscreants to connect with you quite easily. Social networking users should be vigilant about the kind of information they share online and the crowd with which they interact. Often women overlook the potential dangers of social networking sites. A simple socially engineered chat message with a malicious URL or a wall post of a “video link” especially of a cute baby/shopping offer could attract many victims to silently seed malware into their computer, as witnessed in the case of the Microsoft Windows worm Koobface.  This allows hackers to either gather the user’s personal information or infect the computer.

With the stolen valuable information, miscreants can potentially cause distress to a user, especially to women and children.

One should also be keenly aware that photos shared on these social networking portals are viewable by even unintended audiences and can be morphed and redistributed without one’s consent. Young women tend to be the most likely targets of online harassment such as cyberbullying, trolling, stalking and death threats. This harassment gets even more dangerous if it manifests itself in real life. Even in the virtual world, targeted online harassment has the potential to cause severe mental trauma.

In order to curb such online threat issues, the Computer Emergency Response Team (CERT) educates internet users about safe surfing, helps the public report online abuse, and offers recovery procedures.

Here are some simple tips to make women more social networking wise:

  • Never disclose sensitive information such as date of birth, location, phone number, address, etc.,
  • Incorporate privacy and security settings offered on social networking sites
  • Beware of clicking on links and opening messages from unknown sources
  • Think twice about accepting requests to connect from strangers
  • Secure your computer with a good antivirus solution

to second part…

Image courtesy of:
crisistextline.org
freenet-work.tk/wordpress/wp-contents/2014/08/social-network.jpg

Archana Sangili, Content Writer
V.Dhanalakshmi, Senior Threat Researcher, K7TCL

If you wish to subscribe to our blog, please add the URL provided below to your blog reader: http://blog.k7computing.com/feed/

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

If you wish to subscribe to our blog, please add the URL provided below to your blog reader:
http://blog.k7computing.com/feed/

Exorcising CTB Locker from your Computer: What you Need to Know

Friday, January 30th, 2015

Ransomware, a type of malware which holds your files to ransom by encrypting them and then demanding a ransom for their “release”, i.e. by decryption, is nothing new. Cyber criminals make a lot of money by extorting funds from victims all over the world.

The latest family of widely distributed ransomware is called CTB Locker. In this blog we have decided to provide information about CTB Locker in the form of an FAQ so that our customers and the general public globally may be well-informed about the dangers of this malware family, learn how to avoid it, and be reassured about our robust response to it.

FAQ

  • How do you prevent your computer from becoming infected by CTB Locker?

Let’s begin with this question as it is the most important one to keep your computer safe. Prevention is always better than cure.

The initial spreading vector for CTB Locker is a spam email with enticing content which uses social engineering techniques to convince the potential victim to unzip a ZIP archive attachment (extension ‘.zip’) and execute its embedded file.

This embedded file, which is currently around 40KB in size, may have misleading extensions such as ‘.scr’ in order to masquerade as a screensaver application. This file is the downloader component for CTB Locker’s main payload, which then does the actual file encryption and makes ransom demands. We urge you to be vigilant against such spam emails as it is very first line of defence against CTB Locker as well as a host of other malware families which also use the same old time-tested technique to spread.

If an email comes from an unknown or unexpected source containing an attachment or a website link requesting you to open the attachment or click on the link, please exercise extreme caution. We would suggest simply deleting such emails if they are not already quarantined by your spam filter.

The spam emails tend to be targeted at English-speaking countries and at least 3 European countries given that the malware payload provides its ransom messages in German, Dutch and Italian.

This ransomware is not targeted at Indian users per se but given the ubiquitous nature of spam there will be “collateral damage” resulting in not just Indian victims but also many other hapless victims in other non-target countries.

  • What should you do when you discover your computer is infected with CTB Locker?

If you have seen messages demanding a ransom as shown above, it is likely that many, if not all, of your personal files such as Microsoft Office documents, PDF, TXT, ZIP and even ‘C’ source code files will be in an encrypted state, i.e. appear to contain random binary junk. Files encrypted by CTB Locker will have filenames such as yourfile.ext.<7 random lowercase letters>, e.g. 253667.PDF.iryrzpi

Executable files, e.g. EXE, DLL, OCX, etc, and files with extensions unknown to the malware will not be touched.

First and foremost, we would request that you do not attempt to pay the ransom to get your files back. Even if the cyber criminals do actually decrypt your files, the money they get from you will only serve to encourage them to continue their nefarious practices, investing R&D in enhancing their capabilities and global reach. Cyber criminals must be stripped of their Return on Investment incentive to create malware.

Once you have decided not to pay the ransom we would recommend removing the malware immediately. This can be done most easily by:

  1. updating your product
  2. rebooting into Safemode
  3. performing an on-demand scan on your computer
  4. removing the detected components. Note, the main CTB Locker payload is detected as ‘Trojan ( 0049d83b1 )’ and its downloader component is detected as ‘Trojan-Downloader ( 00499db21 )’

  • Is it possible to decrypt files encrypted by CTB Locker?

The malware itself demonstrates that files can be decrypted by randomly choosing 5 samples to decrypt.

However, the malware uses a high-grade encryption algorithm with a key which is unique to your computer, rendering it effectively impossible to force a decryption en masse.

  • How to restore files encrypted by CTB Locker?

It may not be possible to restore all files encrypted by CTB Locker. However, if your Windows operating system supports System Restore it is possible to recover the contents of many of your folders to a recent restore point before the infection took place.

The most reliable solution, though, is to restore your critical files from regular backups. If you don’t backup your important files regularly then we urge you to start doing so ASAP. Apart from a CTB Locker infection, there are numerous other factors which could render your files irrecoverable in the future, including a hard disk failure. Note, it may also be possible to use deep forensics tools to recover some critical files if they still exist on sectors on the hard disk, but this is not an alternative to regular backups.

  • Will paying the ransom actually decrypt your files?

We refuse to pay any ransom so we are unable to confirm whether payment will actually result in your files being released. Once again, we would request you to not attempt to pay the ransom for the reasons mentioned earlier.

  • Why did K7 not detect and remove CTB Locker?

At K7 Threat Control Lab we are constantly monitoring and acting against CTB Locker infections, including coding robust generic detection for all components of CTB Locker. However, the cyber criminals behind the CTB Locker family have been investing considerable resources in morphing, i.e. changing the appearance of, all their components and spam emails such that they may sometimes be able to get past security scanners, not just K7’s, albeit for a very short period of time. We at K7, and our colleagues at other security companies, are working hard to stay ahead of CTB Locker in order to protect all our customers across the planet.

Samir Mody
Senior Manager, K7TCL

If you wish to subscribe to our blog, please add the URL provided below to your blog reader:

http://blog.k7computing.com/feed

Hacked Websites: Consequences and Mitigation

Wednesday, January 28th, 2015

This is the final chapter of my blog series on “Hacked Websites” describing the consequences faced by users of visiting a hacked website, along with a few mitigation guidelines for the developers and webmasters, following on from the previous chapter covering the vulnerabilities and exploits involved in a website compromise.

Back in the old days, hackers used to hack to try to solve problems, to improve internet security and experience, and to boost their own self-esteem. Over time, hackers’ intentions changed and they began to hack for many more troublesome reasons such as to deface a website and convey a specific message, to steal confidential data or services, to host illicit material, for malicious redirects, to utilize a server’s resources for malicious intent, DDos, etc; by and large for money, theft of intellectual property, curiosity, prestige and as a publicity stunt.

Consequences for a user in visiting such a compromised website are that a user may

  • become a victim of a socially engineered phishing attack and give away his/her banking credentials, personal information and credit/debit card data on fraudulent sites.
  • become a victim of unintentional malicious downloads and installs (aka ‘drive-by download’), including becoming part of zombie botnet armies.
  • To ensure a safe and secure visit for a user to their website, webmasters must periodically verify their websites’ integrity. Below are a few of the mitigation guidelines for both developers and webmasters.

    For developers :

    ●     Implementation of effective input/output validation and sanitization approach.
    ●     Implementation of effective account management, authentication and authorization practices.
    ●     Encrypting users’ secret session values and sensitive data.
    ●     Securely handling exceptions, errors and logs.
    ●     Following the standards described in OWASP, CERT guidelines.

    For webmasters :

    ● Do not entertain cloaking, link farming, content autogeneration and other SEO tactics that may welcome SEO Poisoning attacks.
    ● Carefully deliver content from open, restricted and forbidden areas.
    ● Serve sensitive content over secure pipelines such as HTTPS.
    ● Encrypt data (using industry grade encryption algorithms) before storing into database.
    ● Update and patch servers within regular scheduled time intervals.
    ● Perform web application security audits and penetration testing on a regular basis.

    As one would expect, in the event of any compromise of their website, webmasters should carry out the process of clean up and recovery of the hacked website at the earliest with a custom recovery process or by following the guidelines available online.

    I hope this blog series helps people, both laymen as well as webmasters and web developers, in understanding what a hacked website is, the vulnerabilities and exploits involved, and the consequences to a user of visiting a hacked website, and finally the mitigation guidelines for developers and webmasters to reduce the risk of their websites getting hacked.

    Image courtesy of:
    gfi.com

    Priyal Viroja, Vulnerability Researcher, K7TCL

    If you wish to subscribe to our blog, please add the URL provided below to your blog reader:

    http://blog.k7computing.com/feed/

    Are Offline Devices Vulnerable to Spying?

    Tuesday, January 20th, 2015

    Cyber criminals can spy on your PC or mobile phone even when there is no internet connectivity on your device, claim researchers from Georgia Institute of Technology. Apparently, low-power electronic signal emissions, called “side-channel” signals, from laptops and mobile phones can allow hackers to intercept user activities and Android smart phones are particularly prone to these kinds of attacks. Through these signals, hackers may be able to tell when you edit a document, look at photos and when you enter a password, with the help of an antenna and a microphone.

    The difference in the signal emission by the processors is said to help deduce the operation that is being performed on the device. The GIT researchers asseverate that there exists a design flaw in devices that makes them vulnerable to hackers, who are able to eavesdrop on user activities from a few feet away. The victim on the other hand, will be denied even the benefit of doubt since there is no way to tell that signals from your devices are being tapped. Despite speculation about this kind of exploitation there is no evidence of any attack so far.

    Cyber criminals are always on the lookout for ways to infiltrate the user’s device to steal information. Even if it were possible to gather information through side-channel emissions, we believe that cyber criminals would not opt for this route on a large scale. The nature of professional cybercrime is such that the distance between victim and attacker is generally several thousand kilometers, i.e. over a network of interconnected devices. It is hardly likely that a cybercriminal would tune into emissions from the user’s device from just a few feet away. The probability that a hacker can match a password to the corresponding website when you type in a password on your device or decide which emission comes from which particular individual’s device seems pretty low. In any case let us await independent verification of the alleged design flaw.

    Image courtesy of:

    http://ispyck.com/tscm-services/

    Archana Sangili, Content Writer

    If you wish to subscribe to our blog, please add the URL provided below to your blog reader:

    http://blog.k7computing.com/feed/