erica

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed Extension: .erica (appended after the original extension, e.g., Document.docx.erica)
  • Renaming Convention:
  • Keeps original file name intact, simply concatenating the new .erica extension
  • Drops the ransom note as README_TO_RESTORE_FILES.txt or README_!!!recover_me!!!.txt in every folder it touches

2. Detection & Outbreak Timeline

  • First Public Sightings: 25-26 May 2021 (caught by ID-Ransomware submissions, Twitter SOC reports, and upload spikes to Any.Run)
  • Peak Activity: Mid-June 2021; campaigns still resurfacing in smaller waves through February 2022

3. Primary Attack Vectors

  • Exploitation of ProxyLogon (CVE-2021-26855/26857/27065) – the attacker’s favourite for Exchange-facing organizations
  • RDP-envelope attacks – credential stuffing or purchasing prior user/password combos and manual deployment via PsExec
  • Phishing with ISO/IMG attachments (alleged “invoice” or “voice message” lure) containing the loader “loader.exe”
  • Living-of-the-land privilege escalation through EternalBlue (MS17-010) once inside; additionally lays Cobalt Strike beacon and/or SystemBC for reliable back-door access before running the Erica binary

Note: The campaign is usually double-extortion—PowerShell scripts exfiltrate data to Mega.nz or AnonFiles first, then the binaries are executed to encrypt.

Remediation & Recovery Strategies

1. Prevention

  • Patch Exchange servers all the way through the 2021 HAFNIUM/ProxyLogon roll-ups; disable external ECP/OWA if not required
  • Enforce Windows updates that close SMBv1/EternalBlue (MS17-010 disabled by default in Win10 since 2017)
  • MFA on all RDP/VPN endpoints; enforce NLA; restrict RDP 3389 behind VPN-only access
  • Application whitelisting/Crypto-Guard features in Microsoft Defender (or equivalent) to block mass file-extension change behaviour
  • Routine, offline, immutable backups (3-2-1 rule) with a gap between live file-shares and repository
  • Disable Office macros via Group Policy, disable auto-mount/open of IMG/ISO attachments in mail filters/gateways

2. Removal (summary checklist)

  1. Physically disconnect the machine from LAN/Wi-Fi
  2. Boot a clean USB with updated AV/EDR rescue ISO (Windows PE or Bitdefender/Kaspersky rescue)
  3. Kill the following observed mutexes/services if present:
    Mutex: EricaMutex_9381, EricaSucks
    Service: EricaServ –> executable path /Windows/Erica.exe or /Users/*AppData/Local/Erica.exe
    Scheduled Task: EricaSynch – remove in schtasks
  4. Let AV/EDR delete dropper artefacts (loader.exe, svchosts.exe, explorerer.exe) + Cobalt Strike beacons or SystemBC
  5. Check PowerShell history (Get-History, $ENV:APPDATA\Microsoft\Windows\PowerShell\PSReadLine) for download cradle of Erica.exe and wipe unwanted modules
  6. Reboot, rerun a full scan to verify residual binaries removed
  7. Before reconnecting to the network, reset local admin credentials, audit LAPS, change all privileged AD accounts, and apply new MFA tokens

3. File Decryption & Recovery

  • Feasibility: Erica uses Curve25519 + AES-256-CTR (per file) with key pairs generated on-the-fly and encrypted by an embedded master public key (offline). Currently there is no public decryptor.
  • Potential cases of partial recovery:
  • If the malware process was interrupted, un-synced offline backups or Volume Shadow Copy remain (it removes them with vssadmin delete shadows /all but timing matters).
  • For NTFS volumes without TRIM, carve original pre-encryption files with PhotoRec/Scalpel if disk has been little used post-attack.
  • Only when victims obtained the bundled private key — either through (a) successful law-seizure operation or (b) the operator released master key during an exit/scandal — can we build a universal tool. No such key has surfaced.
  • Keep copy of encrypted sample + ransom note; register them with NoMoreRansom.org so researchers can alert if a working decryptor later appears.

4. Other Critical Information

ID-Signatures

  • Ransom note string: All your files have been encrypted by ERICA RANSOMWARE.
  • E-mail addresses: [email protected], [email protected], and a TOX-ID (090F2287…) in later builds
  • They threaten to publish exfiltrated documents on a blog site (data leak site) reachable via Tor: hxxp://erica6xlo7rcp5iz6xbljv4hc7mh6r3x6qsudjxosrqvvc3mykq447eid.onion

Unique Characteristics

  • Deletes local anti-virus logs (C:\ProgramData\Avast*\logs\) before launching encryption to hamper triage
  • Leaves a “marker” JSON file "EricaInfo.json" with computer name, victim-ID, and encrypted AES key which incident-response teams can use to identify variant quickly
  • Because it does not change filenames (other than adding .erica), some users assume “regular corruption” or even “Windows Update issue,” delaying incident classification—be certain to look for the marker file

Broader Impact

  • Healthcare, legal, and manufacturing sectors were heavily hit in June 2021; several regional hospitals admitted to EMR downtime for more than a week, showing that the group bases targeting on available ProxyLogon exposure rather than company size
  • Double-extortion trend (data theft then encryption) increases compliance risk (HIPAA, GDPR)—possibility that PHI/PII appears on their leak site must be factored in breach notifications

Quick-Reference Tools / Patches

  • MS Exchange cumulative security update for ProxyLogon (March 2021 rollup)
  • Microsoft MS17-010 patch or KB5022282 (disable SMBv1)
  • stordiag.exe (Microsoft) – inspect VSS integrity after infection
  • Kaspersky AVPTool / Bitdefender Rescue CD – free bootable males
  • ESETEricaraDecryptor.exe – as of now, does not exist; placeholder name to watch for on NoMoreRansom page

Stay patched, keep backups off-site, practice least-privilege—and if .erica files surface, snapshot RAM first (presenting a small chance to extract the session AES private key before it is wiped) before powering down and beginning the removal work-flow above.