Lawrence Abrams, for Bleeping Computer, describes how the SyncCrypt Ransomware Hides Inside JPG Files, Appends .KK Extension.
The article describes ransomware discovered by EmsiSoft’s xXToffeeXx, distributed as spam attachments containing WSF (Windows Script File) objects. The WSF script pulls down images containing embedded Zip files. Abrams reports that the ‘WSF attachments are pretending to be court orders with file names like CourtOrder_845493809.wsf.’
VirusTotal searches today indicate that detection is rising of the image file for which a hash is provided, but still lower than the detection rate for the executable, which the majority of mainstream security products now detect. The JPGs are not directly harmful, but the embedded Zip file contains the malicious sync.exe executable. Detection of the WSF file for which a hash is provided is also lower than for the executable.
There’s no free decryption for affected data at this time.
IOCs, filenames etc. are appended to the Bleeping Computer analysis.
Cybereason: Researchers at Cybereason have discovered a new strain of the Cerber ransomware that implements a new feature to avoid triggering canary files.
Apparently this strain of Cerber assumes that any malformed image file is a ‘canary’ file (a variation on the old idea of a goat file) and avoids encrypting it or any other file in the directory in which it’s found.
A goat file can be used to facilitate detection and/or analysis of a virus when it has been infected, by analogy with a ‘sacrificial goat’.
A canary file is intended to act like ‘a canary in a coal mine’, giving early warning of an attempt by ransomware to encrypt files, by analogy with a canary dropping unconscious or dead at the first hint of dangerous gases such as carbon monoxide.
Since it’s rather easy to generate a ‘malformed image file’, it’s been suggested that people do so to help protect folders containing valuable files. I suspect, however, that the Cerber gang (and other malefactors) have already twigged that one, so I certainly wouldn’t rely on such a strategy.
WordFence, which offers a security plugin for WordPress sites, reports on Ransomware Targeting WordPress – An Emerging Threat, claiming to have ‘captured several attempts to upload ransomware that provides an attacker with the ability to encrypt a WordPress website’s files and then extort money from the site owner.’
I hope the company won’t mind my quoting this important paragraph:
If you are affected by this ransomware, do not pay the ransom, as it is unlikely the attacker will actually decrypt your files for you. If they provide you with a key, you will need an experienced PHP developer to help you fix their broken code in order to use the key and reverse the encryption.
Commentary by HelpNet Security here: EV ransomware is targeting WordPress sites
SecurityWeek contributor Kevin Townsend asked me about a report from the UK’s De Montfort University on the psychology of ransomware splash screens. Here’s the article he published – Researcher Analyzes Psychology of Ransomware Splash Screens – and here are some further thoughts from me published on the ESET blog: Social engineering and ransomware.
Lawrence Abrams for Bleeping Computer: Reyptson Ransomware Spams Your Friends by Stealing Thunderbird Contacts. He says:
‘…unfortunately there is no way to decrypt this ransomware currently for free. We have, though, setup a dedicated Reyptson Support & Help Topic for those who wish to discuss it or ask questions.’
Announcement by EMSIsoft’s @PolarToffee.
Notes from @malwrhunterteam
AV-Test offers an interesting aggregation of 2016/2017 malware statistics in its Security Report here. Its observations on ransomware may be of particular interest to readers of this blog (how are you both?) The reports points out that:
There is no indication based on proliferation statistics that 2016 was also the “year of ransomware“. Comprising not even 1% of the overall share of malware for Windows, the blackmail Trojans appear to be more of a marginal phenomenon.
But as John Leyden remarks for The Register:
The mode of action and damage created by file-encrypting trojans makes them a much greater threat than implied by a consideration of the numbers…
Looking at the growth in malware for specific platforms, AV-Test notes a decrease in numbers for malware attacking Windows users. (Security vendors needn’t worry: there’s still plenty to go round…)
On the other hand, the report says of macOS malware that ‘With an increase rate of over 370% compared to the previous year, it is no exaggeration to speak of explosive growth.’ Of Android, it says that ‘the number of new threats … has doubled compared to the previous year.’
Of course, there’s much more in this 24-page report. To give you some idea of what, here’s the ToC:
- The AV-TEST Security Report 2
- WINDOWS Security Status 5
- macOS Security Status 10
- ANDROID Security Status 13
- INTERNET THREATS Security Status 16
- IoT Security Status 19
- Test Statistics 22
Microsoft describes the new Windows 10 feature ‘Controlled folder access in Windows Defender Antivirus’ in the article Announcing Windows 10 Insider Preview Build 16232 for PC + Build 15228 for Mobile. The article specifically mentions ransomware as one of the threats against which it is likely to be effective.
The article states that ‘Controlled folder access monitors the changes that apps make to files in certain protected folders. If an app attempts to make a change to these files, and the app is blacklisted by the feature, you’ll get a notification about the attempt. You can complement the protected folders with additional locations, and add the apps that you want to allow access to those folders.’
It’s not clear what criteria are used to blacklist an application: as I read it, it may simply use Windows Defender’s scanning engine to determine the status of an app. I guess I’ll wait for more information before deciding how much additional protection this really provides.
Zeljka Zorz comments for Help Net Security :
Whether this security feature will be enough to stop ransomware remains to be seen, especially if ransomware can get a whitelisted application to bypass the protection and offer a way in.
I wasn’t really thinking of this in terms of whitelisting until I read that, but the feature does, in fact, allow the user to add protected locations apart from the default folders, and also to ‘ Allow an app through Controlled folder access’. Which opens the door to social engineering as well as subversion of apps, but then that’s a persistent issue with whitelisting applications.
(MacSpy isn’t ransomware, but seems to have been developed by the same author, and both are offered as as-a-service malware.)
Zeljka Zorz for HelpNet Security: Two Mac malware-as-a-Service offerings uncovered. According to HelpNet ‘Patric Wardle’s RansomWhere? tool can also stop MacRansomware from doing any damage.’
Rommel Joven and Wayne Chin Yick Low, for Fortinet: MacRansom: Offered as Ransomware as a Service
Fortinet notes that “Nevertheless, we are still skeptical of the author’s claim to be able to decrypt the hijacked files, even assuming that the victims sent the author an unknown random file…”
AlienVault: MacSpy: OS X RAT as a Service
A couple of items of general interest regarding ransomware:
I’ve commented a couple of times recently on the question of Ransomware: To pay or not to pay? and The economics of ransomware recovery.
A free tool released by ESET ‘to help combat the recent ransomware, WannaCry (WannaCryptor).’
The press release goes on to say that:
ESET’s EternalBlue Vulnerability Checker can be used to determine whether your Windows machine is patched against EternalBlue, the exploit behind the WannaCry ransomware epidemic that is still being used to spread cryptocurrency mining software and other malware.
This obviously isn’t the only way to check, and it may not be the only tool of its kind out there – I haven’t been looking for such a tool. And clearly, checking for a specific vulnerability isn’t a substitute for a sound patching strategy, or for using security software that detects malware (including WannaCryptor) reasonably reliably. But while I haven’t tested it personally, I’d be very surprised (in view of my longstanding association with ESET) if this tool didn’t do what it says on the tin, so some people and organizations might well find this useful.