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Mischa is a Windows file-encrypting ransomware closely associated with the Petya ransomware family and the Janus ransomware-as-a-service operation. It was introduced as a fallback payload for cases where Petya could not obtain the administrative privileges needed to overwrite the master boot record and encrypt the master file table. Unlike Petya’s disk-level approach, Mischa performs conventional file-by-file encryption and can operate with only user-level privileges, making it effective even when elevation fails.
Mischa has been distributed together with Petya through spam and phishing campaigns, including job-application themed lures, as part of a dual-payload installer. The installer decrypts embedded Petya and Mischa components and selects which ransomware to deploy based on the privileges of the current process token. When Mischa is chosen, the payload is prepared with victim-specific data and injected into legitimate Windows processes using reflective DLL injection, including execution via remote threads.
The malware targets a broad range of file types across fixed, removable, and remote drives, while excluding certain system and application directories to preserve system operability. It is notable for encrypting not only user documents and archives but also executables and libraries. Mischa can operate offline without retrieving keys from command-and-control infrastructure. It generates encryption material locally, uses per-file random data in its encryption workflow, appends victim-specific metadata to encrypted files, and drops ransom notes for the victim. Reporting has also noted code similarities with other ransomware families such as Chimera and Rokku.
Mischa is generally characterized as a straightforward but effective ransomware family whose fallback role significantly increased the success rate of Petya-linked campaigns. Because it encrypts files directly rather than relying on filesystem metadata disruption, recovery may be more difficult in many cases than with some early Petya variants that suffered from cryptographic implementation flaws.
Mallory pivots from this family to the IOCs, detections, and named campaigns that touch your stack, and pages you when something new lands.
1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
If Petya has insufficient privileges to access MBR on HDD (Hard Disk Drive), the Mischa module is deployed and encrypts files one by one.
17 distinct techniques documented for this family, organized by ATT&CK tactic.
This ransomware is primarily spread via spam email campaigns using different variations with different types of attachments (zip, pif, .pdf.exe, ..) or links to various online storage services. The fake emails looks like job applications, job offers, legal proceedings, among other things.
After such preparation, Mischa.dlll is injected to conhost.exe and deployed as a remote thread.
Mischa.dlll is injected to conhost.exe and deployed as a remote thread.
The dropper is simple and doesn’t contain any anti-debugging tricks, but it is very strongly obfuscated with a ton of junk code instructions and also uses self modifying methods.
After such preparation, Mischa.dlll is injected to conhost.exe and deployed as a remote thread.
Mischa.dlll is injected to conhost.exe and deployed as a remote thread.
The dropper includes the XORed payload, which contains Petya’s bootloader and the Mischa module... In the first step, the Petya bootloader and the Mischa module are decrypted, using a simple 1-byte XOR algorithm.
After decrypting the payloads, an environment check is performed in order to choose which one of them will be installed. The process token... is used for choosing which installation path to follow next. Dropper comes with a list of Anti-Malware products, which presence is checked before the payload is deployed.
The payload checks which privileges it has via the GetTokenInformation API function... The OS version verification is performed using an interesting method via the API functions VerSetConditionMask and VerifyVersionInfoW... The verification of the installed AV product is done by searching folder names inside “Program Files” or “Program Files (x86)” and comparing the results with the hardcoded list.
The verification of the installed AV product is done by searching folder names inside “Program Files” or “Program Files (x86)”... The folder search is carried out using the GetFileAttributesA API function... Mischa avoids the following directories...
Mischa fetches the list of mapped drives (GetLogicalDriveStringsA) and identifies the drive type by a Windows API function: GetDriveType. It attacks removable, fixed and remote drives.
Mischa is able to encrypt data on all local drives, connected USB drives and remote drives.
After decrypting the payloads, an environment check is performed in order to choose which one of them will be installed. The process token... is used for choosing which installation path to follow next. Dropper comes with a list of Anti-Malware products, which presence is checked before the payload is deployed.
14 indicators attributed across vendor reports, sandbox runs, and researcher write-ups. Full values are available in Mallory.
IPs, domains, and DNS infrastructure linked to this family.
File hashes (MD5, SHA-1, SHA-256) from samples and reports.
Other indicator types observed in public reporting.
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Secondary file-encrypting ransomware component bundled with Petya; activates when the user denies Petya administrative privileges and encrypts individual files (including .exe files).
Companion ransomware to Petya that required only user-level privileges and encrypted files in the traditional manner.
Petyaと連携してファイル暗号化を担当するランサムウェアとして説明されている。
Referenced as one of the ransomware strains created by the same author associated with Petya/NotPetya.
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.