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Archive for the ‘Security news’ Category

Real or Fake App?

Friday, July 31st, 2015

This blog intends to discuss a few real-time difficulties in identifying whether a downloaded Android application is safe or not, along with a few precautionary steps for Android smartphone users to follow when downloading an application.

Year-on-year, smartphone usage in India is growing at an enormous rate. These days almost everything is mobile, i.e. smartphones have accommodated users in such a way that users welcome applications even for their day-to-day commercial activities like paying bills, ticket booking, etc.

Now, there arises a serious question of trust, “How far is the downloaded application safe?” It is generally believed that an application can be reasonably judged by the permissions that it requests from the user during installation. Unfortunately, in recent times, most of the legitimate applications are seen to request permissions that appear to be in no way related to their current core functionality, but only in view of the application’s future enhancements.

Recently, I came across a popular taxi booking application requesting permission to access media files (photos/videos) as shown below.

The above scenario was observed in a well-known banking application as well.

I would also like to share another interesting incident. A couple of days ago, we at K7 Threat Control Lab, received a “false positive” report from an end user claiming that a famous game application has been flagged incorrectly.

Upon further investigation, it was noticed that the application is actually a fake installer. Unlike the original game app, this fake application tries to download further applications.  The above described unexpected behaviour from a game application is not acceptable.

With many other potentially fake applications of this kind doing the rounds and the latest trend of online portals moving onto app-only services, the security risk level is certainly increasing. Worst-case scenario could involve the case of mobile wallet applications, where a user may also save his/her credit card information for future use.

It goes without saying that identifying an application as suspicious or safe remains a tough job especially for an end user. With a mobile malware application exhibiting similar permission requests and functionality to a legitimate application, the malware analysis process is complicated. Security experts invest more time in code and metadata study to confirm an application as safe, one example being the exhaustive permissions list requested by both  legitimate and malware applications, that may not even be needed for their operation.

Even though the risk cannot be eliminated completely, it can be effectively reduced by following the following oft-stated traditional but yet effective precautionary steps:

  1. Think twice before you download an application whether you really need it.
  2. Download applications only from the official Playstore.
  3. Use the “Verify apps” feature from the Android OS to check whether the app is safe or not.
  4. Install trusted mobile security software, also typically downloaded from the official Playstore.

V.Dhanalakshmi
Senior Threat Researcher, K7TCL

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Domain-hungry Spam

Thursday, July 16th, 2015

Here is an account of an unexpected incident that reignited my fading passion for email header analysis. And it was that… a friend of mine got a nasty headache. Ah yes, you read it right.

My friend runs a one-man-show as “the IT guy” for an organization. Every day he goes to work as energetic as he can be and returns completely drained from having to deal with the bulk of unsolicited emails (aka “spam”) that floods the company’s mail server.

But the “headache” was the result of their domain getting blacklisted.

They started receiving tons of bounced emails from mail addresses which meant nothing to them. And at times they even received mails that seemed to originate from their own domain.

He had no clue as to why their domain started receiving huge amounts of bounced back emails or why their emails were not delivered to the intended recipients.

Whilst he was trying to work out why this was happening, the poor domain was marked down for “rolling out bulk emails” and the domain was blacklisted. That explains the delivery failures.

He worked vigorously with the provider to whitelist the company’s domain; but the issue repeated itself in an uncontrolled fashion that it became a part of his routine to bail out the domain.

He wanted to find if the computers on the office network were infected by some malware and how their emails are being hacked, especially given that they have one of the best Anti-Virus products installed and a good set of security policies in place.

And his plea to take a look into the issue pushed me to awe Joe.

Scrutinizing the few email headers he showed me, I was able to identify that a rare form of spam attack nicknamed “Joe job” was causing damage to the company and its domain’s reputation.

So what actually is a “Joe job”?

A spammer can craft the email header to make it appear to come from a spoofed sender, i.e. the recipient would see something like “john@domain.com” in the “from” address but the actual sender would be someone else.

Also, the “reply-to” field can be played with so that any responses or bounce-backs would be redirected not to the address in the “from” field but to the one specified in the “reply-to” field.

Spammers use this technique for various reasons including hiding their identity, escaping the issue of handling undesired bounced-back/non-deliverable emails, skipping spam filters and stealing the victims’ bandwidth.

Here is a description of the original attack for reference: http://joes.com/spammed.html

Though the Sender Policy Framework records (SPF records allow domain owners to publish a list of IP addresses or subnets that are authorized to send email on their behalf) and security policies are properly set up, a few misses while configuring the mail server ended up feeding the domain’s reputation to spammers in this case.

It is important to remember that spam filters cannot be too rigid, but a simple rejection of bounced back emails from unknown senders could have saved the domain, to some extent, from falling prey to such spam attacks and causing a headache for my friend (although this did rejuvenate my fading passion…).

Image courtesy of:
blog.antispam.fr/wp-content/uploads/2013/03/email-bounce.jpg

Ayesha Shameena P
Threat Researcher, K7TCL

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Patch Released, Before You Can Say ‘Patch Tuesday’

Friday, July 10th, 2015

Microsoft is set to do away with its cycle of serving up security updates, released on the second Tuesday of every month. This is (un)officially known as ‘Patch Tuesday’ in tech circles.

In an earlier blog post, we had mentioned that Microsoft is doing all it can to beef up on their security front. Along the same lines, this is also a move to ensure that any security update, critical or not, will reach a Windows 10 user immediately and will no longer have to wait for a month.

Yes, updates will be rolled out 24/7 year round for all devices that run Windows 10, thereby potentially reducing the time taken to address a security issue once it is found. These releases are not restricted to security updates alone, but any software enhancements would also follow the same pattern.  A round-the-clock approach updating the OS infrastructure could also improve the quality of the updates; in the past there have been issues with unstable patches.

While the month-on-month cycle is going to remain for Business and Professional users, Microsoft has reworked this under the title Windows Update for Business. This would provide features to prioritize patching based on chosen devices, to specify timeframes during which updates should occur, and peer-to-peer delivery of the updates for bandwidth conservation in an environment of a large number of computers.

This expedited update schedule is primarily aimed at securing devices ASAP once a security lapse has been identified and fixed.  Though Microsoft claims that users will be provided free lifetime upgrades, the timeframe might in fact be tied down to the type of device that the OS is running on and the device’s supported lifetime.

Perhaps Microsoft is taking the timely patching of security lapses to an even higher level since many supposedly dead and dried malware (Conficker, etc.) that aren’t supposed to be spreading are still doing the rounds just because a patch hasn’t been applied. It is imperative that we as users take security, at least as seriously as Microsoft appears to be doing.

Image courtesy of:
keepcalm-o-matic.co.uk

Kaarthik R.M
K7TCL

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Citizen to Netizen in Digital India: The Need to Secure Cyber Space

Thursday, July 2nd, 2015

The Honourable Prime Minister of India, Shri Narendra Modi, launched the Digital India project yesterday, an ambitious undertaking to interconnect and deliver government services to India’s 1.25 billion citizens.

Fortunately, the challenge of securing the vast cyber space for netizens has been keenly recognised by the Government of India as the Prime Minister stated the following in his speech:

“I dream of a Digital India where cyber security becomes an integral part of national security”

The Prime Minister made unambiguous references to the potential vulnerability of India’s current and future critical infrastructure and services to cyber-attack. The plethora of international spying, hacking, and Denial-of-Service attacks, which have made the headlines in recent times, allows one to put things in perspective. India has its own share of inimical nation states, along with non-state actors, both beyond as well as within the country’s borders.

The Prime Minister also recognised the dangers posed to an average netizen at a personal level. He related how common theft has progressed from stealing somebody’s wallet on a bus, in the past, to the current ability of criminals situated thousands of miles away to wipe out a bank account within the time it takes to click one’s fingers.

Indeed, as highlighted previously on our blog, there exists legislation to aid the protection of netizens from common cybercrime, as well as provisions to safeguard national cyber security. However we believe there is lot more to be done. In this blog we wish to highlight certain problem areas which need to be taken into account to boost cyber security for the netizen, and thus, for the nation.

There is a lot of emphasis on the use of online social media and sharing of data “securely”. Of course netizens are only too keen to share Personally Identifiable Information (PII) on public sites, which may not even be hosted in one’s home country. Apart from its general nuisance value, leakage of PII allows the mounting of sophisticated targeted attacks. We recommend thinking several times before posting private information on public sites.

Plans to provide many services online, including secure private document storage, will require netizens to be made aware of basic security hygiene, at least vis-à-vis the use of strong passwords which must be difficult to crack. However, for ease of remembering, it is likely that many, if not most, netizens would employ the same credentials across multiple portals. The compromise of just one password could leave your data exposed on several other sites. In addition, the secure storage of digital certificates, used to authenticate the source and ownership of documents, is a cause for concern as a stolen certificate could lead to complete identity theft.

The exploitation of vulnerabilities on both the client and server side poses a real and present danger to all users. On the client side, software installed on a user’s computing device can and do have hidden weakness that can be taken advantage of during attacks. Vulnerabilities on the server side, especially web servers, have the potential to compromise thousands, and with the advent of Digital India, perhaps millions. A huge proportion of websites, including many with ‘gov.in’ in the domain name, are not necessarily implemented and managed with security in mind, leaving netizens vulnerable. Several trusted Indian state and central government sites have been hacked and defaced in the recent (and not-so-recent) past. We have blogged previously about website hacking, and remediation techniques with which webmasters ought to be familiar. We hope that the government portals which deliver services will be made robust to any form of attack, particularly intrusion and Denial-of-Service.

Mobile devices are set to play a crucial role in the Digital India project. Android is likely to be the most common mobile platform used to communicate with government portals, given the relatively low cost of Android devices. It must be noted that despite Google’s assertions to the contrary, Android devices are certainly not invulnerable to malware attacks. Mobile devices must also be secured, with the user being made aware of the do’s and don’ts of app installation.

The above list of issues is far from exhaustive. We have touched merely the tip of the iceberg. Covering other potential issues is beyond the scope of this particular blog.

An interconnected, inclusive Bharat via the Digital India campaign is an exciting prospect. We wish the campaign all the very best, and we, as IT security professionals, hope to contribute significantly to its success. We would simply like to reiterate the cyber security threat potential to netizens and the Government of India so that robust security hygiene is maintained with discipline, allowing the freedom of a safe online service experience. Jai Hind!

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

Samir Mody
Senior Manager, K7TCL

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Buy None (maybe)Get One(malware) Free

Monday, June 29th, 2015

Online free software exists aplenty, keenly attracting a user’s attention. The question is, “Are these free software applications really trustworthy?” . With security as the main concern, a computer user must be careful enough while installing any software that is downloaded online. Many of these free software install toolbars or other kinds of unwanted software that are bundled with them.

On the other hand, there are popular free software like Adobe Reader, Adobe Flash Player, etc., that seem to have become an almost mandatory part of computer use these days. Thankfully, these software installs do not include any compulsory extra activity apart from their core functionality, and even attempt to keep themselves secure with regular security updates as and when required.

Security updates are necessary given that many of these free software utilities have loopholes (also known as vulnerabilities) that are left unseen even after they are released to the outside world. These loopholes tend to attract attacks from remote hackers to compromise the user’s computer.

It is a known fact that many users globally, including a high proportion in India, have pirated software (especially the Windows OS) installed on their computers for whatever reason. Historically pirated versions of the Windows OS have not been eligible to receive either security or product updates, leaving the computer far more vulnerable to attack as cyber criminals always strive to exploit a new route or loophole in installed software to enter the target machine.

Therefore one should always be aware of the importance of the security updates. K7 users can run a “Vulnerability Scan” to determine if any known vulnerable components of certain high-profile software exist on the computer. At least in the case of popular free software users are strongly advised to avail of free security updates such as those provided by Adobe Reader, Adobe Flash Player, Java etc., to better guard against unpleasant surprises.

Image courtesy of:
Yadadrop.com

V.Dhanalakshmi
Senior Threat Researcher, K7TCL

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A Nibble of Windows 10 Security

Friday, June 19th, 2015

Windows 10 and its imminent launch have fuelled many discussions within tech circles. In this context we decided to share our thoughts on one interesting Windows 10 security provision.

Windows has had long-term issues with security. Hence over the last couple of years Microsoft has devoted extra resources on bumping up its security focus and image. With recent versions of Windows, Microsoft has added security-centric features like Secure Boot, ELAM, Windows Store Apps and AppLocker, and introduced SmartScreen at a desktop level. In addition, Windows Defender was upgraded from an antispyware solution to an antimalware solution in an attempt to make Windows more secure than before.

With Windows 10, Microsoft is trying to up the ante in terms of security. MMPC recently published an article explaining their new Antimalware Scan Interface (AMSI) which aims to curb malware at the memory level. The article goes on to explain how obfuscation is employed even in script-based malware, from string concatenation to a simple XOR to more complex encryption. AMSI will provide an interface to Anti-Virus products to contextually scan for specific mal-content in a target memory region. An obfuscated mal-script must be fully deobfuscated before it is fed to a scripting engine. Any bonafide security product can register for a callback in this context to invoke a scan of this deobfuscated content using the AMSI APIs provided by Microsoft.

This would aid security vendors since there is no current documented way to intercept a dynamic script buffer. Hence, security products have had to occasionally resort to undocumented methods to attempt intercepting the content fed into the script engine, which could entail stability and performance issues.  Microsoft’s AMSI should prove a more reliable alternative to DIY solutions for script-interception.

Please refer to our earlier blog post for a detailed example of obfuscation in script-based malware.

K7 is getting ready for the Windows 10 release, and we will ensure that all our products are automatically upgraded through regular updates to remain compatible with Windows 10. As a K7 user, there is no effort required from you to prepare for this upgrade.

Images courtesy of:
royalwise.com
encrypted-tbn2.gstatic.com

Kaarthik RM
K7TCL

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My App or No App

Monday, June 1st, 2015

Last week in our K7 Threat Control Lab we came across an Android ransomware “locker” sample with a difference. This one splashes a lockscreen that recommends to the user a list of free applications to install in order to continue using any already installed application as shown below:

However, if the user chooses to install one or all of the listed applications, the list seems endless since a new application is inserted for the one that is chosen for installation. This implies that the user may not be able to access his already installed applications or it might take a long time to exhaust the displayed list to access them. Interestingly, the applications installed from the lock screen list are free to open and are not blocked by the splash screen.

Now let us see how this malware actually works.

Analysis of this locker shows that the AndroidManifest.xml file of the package has RECEIVERS (net.fatuously.Unengaged and net.fatuously.Encephalitis) registered to receive the broadcasts BOOT_COMPLETED, USER_PRESENT, SCREEN_ON, NEW_OUTGOING_CALL, PHONE_STATE and DEVICE_ADMIN_ENABLED respectively. But the registered RECEIVER classes are not referenced in the corresponding classes.dex.

click to enlarge

In addition when this locker sample is executed the application displays an additional custom explanatory message that is also not referenced in the top-level package, as shown in the picture below:

click to enlarge

Digging further it is understood that the APK under study carries within itself an encrypted (XORed) ZIP file (test.dat) in the assets folder which in turn carries the classes.dex file that is loaded at run time.

The studied APK file loads the classes.dex from the encrypted ZIP using the dynamic loading feature as shown in the java source below:

click to enlarge

The RECEIVERS registered in the top-level AndroidManifest.xml and the additional explanation in the Device Admin request screen are referenced in the dynamically loaded unzipped classes.dex file.

click to enlarge

click to enlarge

When the user tries to open any of the applications that is installed prior to the locker, the malware loads the splash screen by setting the splash screen content as the data to the intent “android.intent.action.VIEW” as seen in the following code:

This malware when run without an internet connection, or during application initialization, loads a different splash screen as shown below:

The corresponding code to load the above screen is:

And the contents of none.html are follows:

Base64 encoded data in this HTML contains the image (.PNG) content to be displayed.

A few of the websites to which this malware connects are:

sexualletube[dot]biz
pornigy[dot]biz
pornsage[dot]biz
adeffective[dot]org

Strangely the splash screen does not seem to demand any payment from the user. However, it proves to be malevolent as it does not allow the user to open any application that is installed earlier than the locker.

As we discussed in our VB2014 paper “Early launch Android malware: your phone is 0wned”, an updated boot and broadcast framework in the Android OS that allows the security products to load before any other application will help to keep these locker variants at bay. K7Mobile Security protects its users from this locker with the detection called “Trojan (004c2fc61).”

V.Dhanalakshmi, Senior Threat Researcher, K7TCL

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Rooting for Trouble

Friday, May 22nd, 2015


Despite device manufacturers’ announcement to the user about the void warranty on rooting Android phones, users still root their phones for various reasons such as installing special applications that runs only on a rooted device, removing built-in apps, USB tethering, turning the device into a Wi-Fi hotspot, etc., compromising on the features of security, performance and at the potential cost of the phone itself, as the user might fail at any step in the device-dependent process of rooting the device without a warranty safety net.

Apart from the traditional rooting methods, there are tools available online to root the device that can be run through either ADB or installed directly on the device.

One should also be aware that many Android malware require root access (administrative power) to execute the desired malefide functions on the victim’s device. They acquire root access by bundling with other good applications that require root access, by triggering an application in the victim device that requires root access, or by invoking exploits that they carry within themselves, as in the case of Android/DroidDream that carries the exploits RageAgainsttheCage and Exploid. In addition the recent Android PowerOffHijack malware exemplifies the ill-effects on the Android operating system if administrative power is acquired by a malware.

Security enhancements in Android notwithstanding, there are still new vulnerabilities and exploits for the OS being identified regularly. As per the recent Microsoft report that includes statistics on vulnerabilities and exploits reported in the second half of 2014, lots of the non-Windows exploits found on Windows computers are for the Android operating system and Open Handset Alliance.

All this implies that Android smartphone users should:

  • Ponder whether they really need to root the device
  • Be vigilant about the applications downloaded to root the device
  • Download the required application only from the official Google Playstore
  • Turn on the feature of “Verify apps” that is available with Android 4.2 or higher

Images courtesy of:
Talkandroid.com
Rootmyandroid.org
www.techlegends.in

V.Dhanalakshmi, Senior Threat Researcher, K7TCL

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Online Shopping Tips for Fashionistas

Monday, May 11th, 2015

This is the third part of the blog series on women’s cyber safety, discussing “ONLINE SHOPPING”, the popular term doing the rounds in recent times, continuing from the second part which described cyberbullying and its consequences in one’s life . A survey states that the majority of the goods sold online are of fashion categories, which in turn could suggest that there are a huge number of women customers indulging in online/mobile shopping.

The convenience of online shopping is coupled with its own risk. Online shoppers should be aware of the possibility of online fraud as cyber criminals continue to engage cyber space to target credit/debit cards, bank accounts and miscellaneous user credentials to carry out financial transactions.

Online buyers should be aware of the following:

  1. Phishing attacks where a fraudulent website resembles a popular legitimate website enticing the user to carry out financial transactions which results in both monetary and data loss to the user or causes the download of a malware hosted on the crafted website.
  2. One should also be careful about the online portal at which she/he opts to shop, as there are online fraud campaigns reported where the purchased goods are either never delivered or a different product is delivered to the buyer with a time delay. In either case ultimately it is a financial loss to the buyer.
  3. Shop online only through the portals whose website address starts with “https://” (‘s’ stands for secure) with a lock symbol appearing next to it (or sometimes on the bottom right corner of the browser window), which indicates that the portal uses SSL encryption.

With the increasing usage of smart devices, shopping is being made mobile- “SHOPPING ON THE GO”. The number of Indian customers for mobile shopping is growing given the special deals on purchases and the reduced time factor. In addition, the concept of e-wallet has attracted a large user base by presenting the shopper with additional deals and discounts.

E-wallet portals or mobile shopping applications are seen to:

  1. Provide the choice of saving the buyer’s credit/debit card details in their database for future use. This raises the question “how secure is the data stored at the merchant’s end?”
  2. Auto-login with Facebook or Google account. In case of the mobile being stolen or lost, auto-logging in along with saved credit/debit card details might be a recipe for disaster.

Regardless of whether the shopping is through online computers or mobile devices, one should always:

  • Choose a reputed portal by reading through the reviews available and its track record
  • Download the mobile shopping/banking apps from the official app store
  • Think twice before saving your banking information or credit/debit cards details
  • Avoid opening advertisements or mails from an unknown seller or portal

Images courtesy of:

Dealwithus.co.in
betanews.com
globaldatacompany.com
thinglink.com

V.Dhanalakshmi, Senior Threat Researcher, K7TCL

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TeslaCrypt Can Affect You, Gamer or Not!

Monday, April 20th, 2015

Following positive feedback on our blog a couple of months ago describing CTB Locker we have been requested to do a piece on another ransomware, TeslaCrypt.

Ransomware is a type of malware, becoming more common by the day, which denies access to your computer resources, e.g. by encrypting your personal documents, etc., until a hefty sum is paid to the criminal gang which caused the infection. Ransomware is terribly destructive which is why my colleague Gregory and I have decided to present our views on how to curb this scourge at the international Virus Bulletin security conference later this year.

Now then, TeslaCrypt. There has been plenty of publicly-available data on TeslaCrypt since its emergence in February. It is possible that many currently believe that TeslaCrypt attacks only gamers and gaming software. This is not the case, of course. Similar to most other ransomware TeslaCrypt encrypts documents, music and photos. In addition to these common filetypes it also encrypts files with extensions which are used specifically by gaming software.

A fresh sample of TeslaCrypt from a couple of days ago reveals that its functionality has not changed much from its first avatar, even as it is enveloped in new robes to evade detection, which it fails to do, by the by. This “latest version” (VV3) of TeslaCrypt encrypts files with the following extensions:

.sql;.mp4;.7z;.rar;.m4a;.wma;.avi;.wmv;.csv;.d3dbsp;.zip;.sie;.sum;.ibank;.t13;
.t12;.qdf;.gdb;.tax;.bc6;.bc7;.bkp;.qic;.bkf;.sidn;.sidd;.mddata;.itl;.itdb;
.hplg;.hkdb;.mdbackup;.syncdb;.gho;.cas;.svg;.map;.wmo;.itm;.sb;.fos;.forge;
.ztmp;.sis;.sid;.ncf;.menu;.layout;.dmp;.blob;.esm;.vcf;.vtf;.dazip;.fpk;.wb2;
.vpk;.tor;.psk;.rim;.w3x;.fsh;.ntl;.arch00;.lvl;.snx;.cfr;.ff;.vpp_pc;.lrf;.ltx;
.vfs0;.mpqge;.kdb;.db0;.dba;.rofl;.hkx;.bar;.upk;.das;.iwi;.litemod;.asset;.xf;
.bsa;.apk;.re4;.sav;.lbf;.slm;.bik;.epk;.rgss3a;.pak;.big;.unity3d;.wotreplay;
.py;.m3u;.flv;.js;.css;.rb;.png;.jpeg;.txt;.p7c;.p7b;.p12;.pfx;.pem;.crt;.cer;
.srw;.pef;.ptx;.r3d;.rw2;.rwl;.raw;.raf;.orf;.nrw;.mrwref;.mef;.erf;.kdc;.dcr;
.bay;.sr2;.srf;.arw;.3fr;.dng;.jpe;.jpg;.cdr;.indd;.ai;.eps;.pdf;.pdd;.psd;.dbf;
.rtf;.wpd;.dxg;.dwg;.pst;.accdb;.mdb;.pptm;.pptx;.ppt;.xlk;.xlsb;.xlsm;.xlsx;
.xls;.wps;.docm;.docx;.doc;.odb;.odc;.odm;.odp;.ods;.odt;.pkpass;.mov;.vdf;
.icxs;.hvpl;.m2;.mcmeta;.mlx;.kf;.iwd;.xxx;.desc;.der;.x3f;.cr2;.crw;.mdf;


A diff between the extension list then (February-end) and now shows the following entries:

> .sql
> .mp4
< .sc2save

> .zip
< .mcgame

> .mov
< .001

> .vcf
< .DayZProfile

> .dba
< .dbfv

> .dbf

“>” indicates a new entry and “<” indicates a removed entry. Interestingly it appears there’s now a reduced emphasis on gamers and more on the general public, targeting ZIP archives and database-related files, etc.

The main ransom demand splash screen and “help” message remain relatively unchanged:

Note, the threat to double the decryption price is somewhat different from the previous one which, as usual, claimed that the private key would be deleted after the time counter has run down to 0.

Encrypted files still appear as <original file name with original extension>.ecc:

TeslaCrypt still masquerades as the infamous Cryptolocker, a year after its demise, by continuing to create a shortcut on the desktop with the said name:

As can be seen from the above image TeslaCrypt continues to execute itself as a randomly-named EXE at the root of the Application Data directory. It still drops a file called key.dat in the same location. It has been reported that key.dat contains the 256-bit AES symmetric key used to encrypt the target files, which is eminently possible. It is worth mentioning that TeslaCrypt contains references to OpenSSL functions, e.g. BN_CTX_new(), which must be used to perform the encryption. The exact format of key.dat is as yet unknown so we are unsure which part of it may be the AES key.

Thus far we have covered several indicators of compromise, and we hope you are not experiencing an uncomfortable sense of déjà vu whilst reading this blog. Let’s now address the typical queries related to malware, with the focus on TeslaCrypt and other ransomware:

  • How did it get on my computer?

TeslaCrypt’s modus operandi vis-à-vis spreading itself is via hacked websites which trigger exploits for your browser, typically referred to as a drive-by-attack. Other ransomware tend to spread via mass-mailed attachments.

  • How should I prevent an infection?

The malware should be arrested as soon possible before any damage is done. As in the case of any other malware, we would recommend the usual hygienic best practices:

  1. Surf only known, highly-reputable sites
  2. Don’t open email attachments from unknown sources
  3. Keep your security software up-to-date. Some security software such as K7’s Total Security contains Carnivore Technology to heuristically block attempts to exploit your browser
  • Now that I am infected, what should I do?

We’ll have to be brutally honest. In the case of modern ransomware you have found yourself in a difficult situation. It is typically impossible to decrypt the targeted files without the appropriate key. We strongly discourage paying any ransom to potentially obtain the key and recover your files, though, since this would only serve to fund and encourage further criminal activity.

Restoring a previous known good state from OS system restore points is sometimes an option but TeslaCrypt attempts to prevent this escape by deleting the restore points by executing the following command:

vssadmin delete shadows  /all

Instead it is hoped that you would have backed up your important files in a disciplined fashion on external media and/or on online repositories. If you are not in the habit of backing up your files, we would highly recommend this practice. Please note, a general hard disk failure is much more likely to strike you than a ransomware infection!

We hope this content helps build awareness about malware in general and ransomware in particular, with an emphasis on TeslaCrypt, thus aiding the relentless battle against innumerable cyber bandits.

Generic ransomware image (first) courtesy of:
files.itproportal.com

Samir Mody
Senior Manager, K7TCL

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