Microsoft is alerting all Windows users of a new type of ransomware that exhibits worm-like behavior to propagate itself
Microsoft is alerting all Windows users of a new type of ransomware that exhibits worm-like behavior.
“We are alerting Windows users of a new type of ransomware that exhibits worm-like behavior. This ransom leverages removable and network drives to propagate itself and affect more users. We detect this ransomware as Ransom:Win32/ZCryptor.A,” states Microsoft.
The Infection vector
Ransom:Win32/ZCryptor.A is spread through the spam email infection vector. It runs at start-up as soon as ZCryptor is executed.
HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
zcrypt = {path of the executed malware}
In the start-up folder, it drops zycrypt.lnk and autorun.inf in removable drives:
%User Startup%zcrypt.lnk
It also changes the file attributes to be in Stealth mode from the user; it also makes a copy of itself as {Drive}:system.exe and %APPDATA%zcrypt.exe
For Example: c:usersadministratorappdataroamingzcrypt.exe
The Payload
It then displays the ransom note to users in an HTML file How to decrypt files.html
Later it encrypts files in your disk and then will change the file extension to .zcrypt (Eg. <originalfilename.zcrypt>)
Infected machines are observed to have zcrypt1.0 mutex, which denotes that an instance of this ransomware is already running on the infected machine.
The connection has also been observed to the following URL, but the domain is already down while testing:
http://<obfuscated>/rsa/rsa.php?computerid={Computer_ID} where the {Computer_ID} is entry found inside a dropped file %APPDATA%cid.ztxt
For example, c:usersadministratorappdataroamingcid.ztxt
The warning issued by Microsoft also includes information about detection, prevention and recovery from this kind of self-propagating ransomware.
Written by: Imdadullah Mohammed
Author Bio: Imdad is an Information Security Consultant, He is also a Moderator for Pune Chapter of Null – The open security community in India and Also member of Garage4hackers. A true open source and Information Security enthusiast. His core area of expertise includes Vulnerability Assessment and Penetration Testing of the Web application, Mobile application and Networks, as well as Server Hardening.
(Security Affairs – self-propagating ransomware, malware)
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