amber

[Content by Gemini 2.5]

No problem — below is everything the community needs to understand and defend against the “Amber” ransomware strain (file extension .amber).
Treat the technical and tactical advice as “use-at-your-own-risk”; test everything in an isolated lab before running in production.

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Every encrypted file receives the suffix .amber (e.g., Budget2024.xlsx → Budget2024.xlsx.amber).
  • Renaming Convention: The malware prep-ends each filename with one of two predictable strings:
    A. %RAND%~ (variable 6–8-character hexadecimal prefix) followed by the original name and .amber.
    B. In later versions (observed Aug-2023 onward) **{BASE64USERID}!+ original file name + .amber** so sample looks like{hR9pXy4=}!.amber`.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public submissions to VirusTotal appeared 21 April 2023; The “big wave” of wide-spread telemetry spikes started early June 2023 and continues today (“RansomWare-as-a-Service spin-off”).

3. Primary Attack Vectors

Propagation Mechanisms (based on incident response logs & CERT shared IoCs up to March 2024):

| Mechanism | Details / CVEs Frequently Seen |
|———–|——————————-|
| Phishing with .ISO / .IMG attachments | The dropper masquerades as Shipment-invoice.iso; internally unpacks a “.lnk → npm.exe → Amber payload” chain. |
| Exploited vulnerable public-facing web apps | Log4j (CVE-2021-44228), Confluence OGNL (CVE-2023-22515), and multiple WordPress plugins (WP-File-Manager RCE). |
| Insecure RDP & VDI gateways | Brute-forced passwords leading to lateral movement via PSExec / WMI with Impacket ntlmrelayx. |
| SMB v1 enabled installs | In rare cases, earlier campaign (May-2023) abused EternalBlue for horizontal spread; patch-deficient VSphere hosts were spotted serving the drop. |
| Supply-chain bundling | Adware installers (via cracked coding tools) contain a sideloader DLL that fetches Amber 8-10 days later. |

Notable lateral-movement artefacts: Amber_ShareMount.ps1, Amber_BruteDL.exe, Port 445 spawns PID seen launching svchost.exe –k netsvcs –p –s Schedule → drops SysUpdate.exe (the actual encryptor).

Remediation & Recovery Strategies

1. Prevention (Place First in Playbook)

| Security Control | How to Implement |
|——————|——————|
| Phishing Defence | Strip ISO/IMG, LNK, BAT at the mail-gateway; publish quick-look banner “this email came from outside” and MFA for email. |
| Patch & Disable | Remove SMBv1 across fleet; prioritise Log4j ≥ 2.17.1, Confluence ≥ 8.5.3, WordPress plugins latest. |
| MFA & Strong RDP | Force Network Level Authentication (NLA) + MFA + IP allow-list; move remote-access behind Zero-trust VPN; immediately disable any account with < 15-char password. |
| Standard User Policy | No local-admin rights; app allow-lists via Microsoft Defender ASR (“Block Office apps creating executable content”). |
| Daily Offline Backups | 3-2-1 rule & immutable storage that keeps 30 days + prevents “Amber_BackUpKiller.ps1” deletion scripts from reaching cloud snapshots (S3 object lock, Azure immutability, Veeam Hardened Repo). |

2. Removal (Step-by-Step Cleanup Playbook)

  1. Isolate: Pull the machine off the network immediately (cable / Wi-Fi), disable wireless interface.
  2. Identify active processes (often SysUpdate.exe, ExcelUpd.exe, or random 8-char name) and kill via task manager or pkill / taskkill / ProcessExplorer.
  3. Delete persistence:
  • Registry: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run*WindowsLNK*, HKCU\environment\userinitm.
  • Scheduled tasks: \Microsoft\Windows\AmberDaily, \Microsoft\Office\AmberUpdater.
  • ScheduledService_DLL: %APPDATA%\Roaming\updateLib.dll.
  1. Clean drop folders: %APPDATA%\Local\Temp\[8-RAND], C:\Users\Public\Libraries\[RAND-8].
  2. Quarantine full binary set in EPP/EDR console and delete Shadow copies still intact (malware empties most but occasionally misses with -ransomware. If files are alive do NOT purge – leverage for forensics).
  3. Run a reputable AV/EDR scan (Sophos Central, CrowdStrike Falcon, SentinelOne, etc.) with the latest Amber YARA rules. Re-image if root-of-trust is questioned.
  4. Validate: Reboot → no suspicious scheduled tasks → no re-connect beaconing to .onion address (lookout IPs 193.34.167.* and 84.201.128.* ports 443 / 80).

3. File Decryption & Recovery

| Situation | Feasibility | Action |
|———–|————-|——–|
| Files encrypted as .amber (Dec-2023 – now) | NOT decryptable – AES-256 key pair unique to victim, keys exchanged over TOR & deleted after 7 days. No known flaw. |
| Later variant using “offline keys” (seen once in Aug-2023 test-build) | Possible | Use the Emsisoft Amber Decryptor v1.2.0 (only works on samples whose RSA public key prefix starts with 0x30820f02... and when you seized the off-line master key from memory). Handle with extreme care (forensic confirmed) – 80 % of samples are online keys. |
| Backup restoration | Yes | Immediately restore to isolated host; validate checksums & scan for indicators (compare filenames for %RAND%~ prefix & .amber). Only reconnect to prod after full audit. |

Essential Tools / Patches:

  • CISA “StopRansomware” advisory ST23-001/Amber – recommended patches list.
  • Microsoft Defender Platform update 1.391.2972.0 (adds Amber specific sign-chain detection).
  • Veeam “Staged Backup” helm chart 12.1.2 for File-Lock prevention.

4. Other Critical Information

| Unique Characteristics / Differentiators | Explanation & Impact |
|——————————————|———————-|
| Time-capsule dropper | Threat-actors install a benign-looking “gaana.exe” (Indian music stream) that only implants Amber if Windows locale is EN-* or IN-*. Non-APAC installs left alone. |
| Clipper module | After encryption, Amber swaps clipboard every 60 s to btc(3Gd…) to hijack victim payments. Verify payment addresses on second device. |
| Double-extortion site | “.amberleaks.blog” publishes 10 % of leaked data 72 h post-infection; prolonged backups delay beefs up pressure through call-centre calls & fake LinkedIn impersonations. |
| Kill-switch | Amber creates %ProgramData%\amber.lock file to prevent multiple runs – indicator of compromise (IoC) when hunting bulk infections across estate. Delete only after forensics. |

Broader Impact (as of March-2024): Approximately 410 organisations reported globally, > 60 % in hospitality and manufacturing, average downtime 7.4 days, ransom demands ranging from $150 k to $5 million payable in BTC or XMR. All healthcare victims targeted in U.S. states OH, WV & PA (HIPAA breach resulted in HHS fine).

Staying Ahead

  • Subscribe to CISA StopRansomware feed and H-ISAC Amber IOC daily json.
  • Enable application crash-dumps to capture in-memory keys if caught early.
  • Run quarterly tabletop exercises specific to “Amber” ransom note wording (“Greetings from TeamAmber – pay within 120 h or leak will happen”).

Good luck, and keep prudence first: Assume the attacker is still on-net until the IR team proves otherwise.