Loading malware…
TeslaCrypt is a Windows ransomware trojan (cryptovirus) that became known for initially targeting video game-related files, including save data, player profiles, custom maps, and mods for games such as Call of Duty, World of Warcraft, Minecraft, and World of Tanks, before later expanding to encrypt common file types such as Word documents, PDFs, JPEGs, and other data. Victims were typically instructed to pay about $500 in Bitcoin for decryption. Early infections were associated with the Angler exploit kit using an Adobe Flash exploit, and the family was also referenced as being spread by the Nemucod malware and delivered by spam infrastructure that also distributed other malware. TeslaCrypt was also hosted on, and used communications infrastructure associated with, the Avalanche criminal infrastructure and fast-flux botnet ecosystem.
Multiple variants are described in the content. Older TeslaCrypt variants used extensions including .ECC, .EZZ, .EXX, .XYZ, .ZZZ, .AAA, .ABC, .CCC, and .VVV on encrypted files. A later TeslaCrypt 3.0 variant, discovered in January 2016, changed its key exchange/protection mechanism so earlier recovery methods no longer worked, and used the extensions .XXX, later .TTT, and later .MICRO. TeslaCrypt 3.0 dropped ransom note files named Howto_Restore_FILES.BMP, Howto_Restore_FILES.HTM, and Howto_Restore_FILES.TXT on the desktop, created recover_file_[random].txt in the Documents folder, stored an executable as C:\Users[username]\AppData\Roaming[random].exe, and used the autorun registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Run\meryHmas for persistence. Additional registry keys mentioned for TeslaCrypt 3.0 are HKCU\Software[random] and HKCU\Software\xxxsys.
The content states that early TeslaCrypt cryptography had weaknesses. Cisco Talos reported early TeslaCrypt used symmetric encryption despite claims of asymmetric encryption and produced a decryptor. Later, researchers and volunteers exploited a flaw in TeslaCrypt’s encryption key storage algorithm affecting older variants, allowing recovery of files without paying the ransom. This weakness applied to variants using .ECC, .EZZ, .EXX, .XYZ, .ZZZ, .AAA, .ABC, .CCC, and .VVV, but not to TeslaCrypt 3.0 variants using .TTT, .XXX, and .MICRO, which fixed the flaw. Community tools mentioned include TeslaCrack and TeslaDecoder, with TeslaDecoder targeting the master private key on the victim system. In May 2016, TeslaCrypt’s developers shut down the operation and released the master decryption key, after which public decryptors were made available. The malware is described in the content as defunct.
Mallory pivots from this family to the IOCs, detections, and named campaigns that touch your stack, and pages you when something new lands.
7 distinct techniques documented for this family, organized by ATT&CK tactic.
Active since 2009, the Avalanche botnet has been used for money muling schemes, distributing a wide variety of malware, and as a fast-flux communication infrastructure for other botnets.
Avalanche used fast-flux DNS, a technique to hide the criminal servers, behind a constantly changing network of compromised systems acting as proxies.
19 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Ransomware family referenced as an example of recognized ransomware strains.
Ransomware family for which AVG provides a decryptor.
A flaw in TeslaCrypt ransomware allows file recovering
Ransomware referenced as an example of a group releasing master decryption keys upon shutdown.
Match every observed IP, domain, and hash against your live telemetry.
Named campaigns wielding this family, with evidence pinned to each claim.
CVEs this family uses for access and lateral movement.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Every documented technique, ranked by evidence weight.
Reddit, Mastodon, and CTI community discussion around this family.