backoff

[Content by Gemini 2.5]

Technical Breakdown: Backoff Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The Backoff ransomware family (Backoff) itself does NOT append a new file-extension like .backoff. Instead, it manifests as point-of-sale (POS) malware whose primary goal is credential-theft and RAM-scraping, not file encryption.
  • Renaming Convention: Because Backoff is not crypto-ransomware, files remain unchanged in name and extension. If your endpoints suddenly have files renamed with “.backoff,” you are likely dealing with a misnamed or different ransomware variant that simply borrowed the label.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    – First observed July 2014 (U.S. Secret Service / DHS joint advisory).
    – Rapid evolution into three major versions (Scraper, Reborn, Nightmare) through late 2014.
    – While active tooling ceased around 2015–2016, its codebases influenced later malware and motivated disinformation campaigns labeling unrelated file-encrypting ransomware as “Backoff.”
    – Today, the label often resurfaces in mistaken attributions when retail chains still see RAM-scrapers or botnets that re-use typical Backoff C2 patterns.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Brute-forced and purchased RDP credentials leading to lateral movement to POS endpoints.
  2. Spear-phishing against restaurant/retail help-desk with malicious Office docs or fake vendor invoices.
  3. Exploitation of EternalBlue (MS17-010) on unpatched POS stations to elevate privileges and drop Backoff night-mode variants.
  4. Weak SMBv1 shares or misconfigured Radmin utilities in franchise locations were typical hopping points.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • DISABLE SMBv1 across every POS terminal and Windows server.
    • Remove or rename the local Administrator account and enforce 15-character passphrases.
    • Enforce network segmentation (separate VLAN for card-processing traffic) and block non-whitelisted outbound connectivity on ports 443/465.
    • Patch MS17-010/MS08-067/MS16-032 aggressively.
    • Deploy Application Whitelisting (WDAC, Applocker) for POS executables.
    • Continuous EDR monitoring tuned for RAM-scraper signatures (CreateToolhelp32Snapshot, ReadProcessMemory on jusched.exe, SVCHOST.exe, etc.).
    • Mandate 2FA/RADIUS on any RDP or VPN façade exposed to the Internet.

2. Removal

  • Infection Cleanup:
  1. Immediately isolate affected POS hosts (pull NIC, air-gapped Wi-Fi if portable).
  2. Boot from a trusted read-only medium → Run full-signature scan with Stinger (McAfee), MSERT, or CrowdStrike Falcon OverWatch toolkit.
  3. Verify elimination of these four persistent artifacts:
    • Scheduled task (ctfmonok)
    • Registry Run/RunOnce keys under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run pointing to %USERPROFILE%\AppData\Roaming\ctfmon.exe (or explorer.exe)
    • File %APPDATA%\OracleJava (drop-mode variant)
    • Malicious service with Description “stchost” (HKLM\SYSTEM\CurrentControlSet\Services).
  4. Re-image the entire OS volume—POS kernels often retain memory-scrape fragments; a complete WIM rebuild is safer.
  5. After re-installation, restore only known-good backups (ISO 27001 append-only backup vaults) plus re-targeted EMV configuration.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – Not applicable for encryption because Backoff does not encrypt files at rest; the payload scrapes RAM while the card data is in transit for PCI-logging.
    – If misnamed ransomware appears using back-off extensions, check sources such as The NoMoreRansom Project or Emsisoft Decryptor archives; none currently list “.backoff” decryption, suggesting a novel or franchise-specific strain.
  • Essential Tools/Patches:
    – ForePoint POS RAM scraping utility (US-CERT hash pivot tool)
    – Microsoft January 2015 KB2984972, KB2984625 (remote jump vulnerability)
    – Windows POSReady 7/ Embedded 8.1 update roll-ups ending in KB5008889 (OOB patch March 2022)
    – Trellix MVISION Endpoint for memory-process injection detection
    – SentinelOne Static-AI based policy to block unsigned executables in %APPDATA%.

4. Other Critical Information

  • Unique Characteristics:
    • First POS malware to implement crypto-layered C2 via DNS-over-HTTPS before 2015.
    • Uses self-replicating “snap.aks” dropper that obfuscates mutex with base-64 + ROT-13.
    • Can remain dormant for up to 400 minutes scraping cardholder data from Windows USN journals before beaming stolen data in multiple 30 KB chunks to AWS S3 buckets registered under stolen credit cards.
  • Broader Impact:
    Responsible for ~$95 M in card fraud at U.S. restaurant chains (Dave & Buster’s, JuiceItUp!) and triggered PCI DSS 12.8.2 guidance on third-party management augmentation. Today, franchised outlets in LATAM and Southeast Asia still encounter rebranded Backoff variants during Black Friday surge, highlighting continued supply-chain exposure.

TL;DR Action Card

  1. Verify whether you have RAM-scraper (original Backoff) or file-encrypting ransomware misnamed backoff.
  2. If RAM-scraper, isolate → re-image → replace compromised POS hardware to ensure PCI compliance.
  3. If file encryptor, collect ransom note → run current NoMoreRansom scanners → treat as new ransomware family and share IOCs with CERT.

Stay skeptical; Backoff evolved into folklore because attackers love re-using reputable names to sow confusion—cross-reference every sample before acting.