Operation TokenBleed: Multi-Tenant AI Cost Spike & FinOps CI/CD Incident
🎯 Incident Briefing: P1 Cloud Cost Anomaly
System: Avanan Multi-Tenant Cloud Email Security
AWS Account: prod-threat-analysis-01 (us-east-1)
Service: AWS Bedrock LLM Inference Gateway (anthropic.claude-3-5-sonnet-20241022-v2:0)
At 09:30 UTC, automated FinOps cost monitors fired a critical P1 anomaly: hourly token spend spiked by +6,180%, jumping from a baseline of $45.20/hr to $2,840.00/hr. At current run-rates, this single inference pipeline will incur over $68,000 per day in unbudgeted cloud charges.
As the person on call, your objectives are:
- Review the real-time incident discussion and CloudWatch telemetry in #incident-finops-tokenbleed below.
- Inspect the Git Release Train (12 commits) and code diffs across our scanning microservices.
- Review the Jenkins CI/CD build logs to determine why our automated FinOps cost guardrails (
finops-cache-lint) allowed this pull request to merge. - Execute the emergency SlackOps rollback command (
/finops rollback --commit <sha>) in the channel message bar. - Complete the incident root-cause triage check with
@FinOps-Guard-Botto authorize the production override and reveal the Incident Audit Signoff URL. - Submit the discovered flag token to verify your solution and unlock the role!
💬 Live Incident Channel: #incident-finops-tokenbleed
prod-threat-analysis-01 (us-east-1)Bedrock/CacheReadInputTokens • Severity: P1-CRITICAL • Incident: INC-7721Team, our Bedrock Cost and Usage Report (CUR) is alerting hard. On Claude 3.5 Sonnet, prompt caching pricing is heavily asymmetric:
- Standard Input: $3.00 / MTok
- Prompt Cache Write: $3.75 / MTok (1.25× fee on write)
- Prompt Cache Read: $0.30 / MTok (90% discount on subsequent reads)
With our multi-tenant security system prompt (~1,240 tokens), when CacheReadInputTokens collapsed to 0%, we lost the 90% discount and are paying a 1.25× cache write penalty on every inbound scan. At this rate, we're burning $68,000/day. What happened in production?
Checked AWS CloudWatch: Zero infra changes. No ECS task churn, no EC2 scaling events. This is definitely not an infrastructure or traffic volume issue.
Bedrock prompt caching requires a byte-for-byte identical prefix of ≥1,024 tokens. If cache read hit rate dropped to 0%, it means the prompt prefix sent to Bedrock is no longer identical across sequential calls.
However, between 08:30 and 09:15 UTC, we deployed Release Train 2026.10-R2 across 4 scanning microservices (12 commits total). Several PRs touched prompt configuration, parsing, or classifier logic.
Here is the Release Train Git log. None of the developers reported breaking the caching policy:
2026.10-R2 (12 commits across 4 services)
Click "View Diff" to inspect code changesservices/auth-tenant/token.py:
- token_ttl = 300
+ token_ttl = 600 # Extended TTL to prevent auth thrashingservices/classifier/regex_rules.py:
+ PHISH_PATTERN = re.compile(r'(?i)(verify|login|secure)-account\.[a-z]{2,}')services/mail-scanner/parser.py:
+ def extract_nested_parts(msg):
+ return [part for part in msg.walk() if part.get_content_maintype() != 'multipart']requirements.txt:
- pyyaml==6.0.1
+ pyyaml==6.0.2services/quarantine/sqs.py:
+ backoff = min(60, 2 ** attempt)
+ time.sleep(backoff)diff --git a/services/mail-scanner/llm_triage.py b/services/mail-scanner/llm_triage.py
@@ -42,8 +42,11 @@ def build_bedrock_prompt(tenant_id: str, email_body: str, trace_context: dict)
# Bedrock Prompt Caching enabled for static security instructions (1,240 tokens)
return {
"system": [
{
"type": "text",
- "text": SYSTEM_SECURITY_RULES_PROMPT,
+ # Propagate OpenTelemetry distributed trace context for end-to-end APM spans
+ "text": f"traceparent: {trace_context['traceparent']}\n\n" + SYSTEM_SECURITY_RULES_PROMPT,
"cache_control": {"type": "ephemeral"}
}
],
"messages": [
{
"role": "user",
"content": f"Tenant: {tenant_id}\n\nEmail Payload:\n{email_body}"
}
]
}services/auth-tenant/telemetry.py:
+ from opentelemetry.exporter.cloudwatch import CloudWatchSpanExporter
+ tracer_provider.add_span_processor(BatchSpanProcessor(CloudWatchSpanExporter()))services/mail-scanner/requirements.txt:
- opentelemetry-sdk==1.25.0
+ opentelemetry-sdk==1.27.0services/quarantine/s3.py:
- CHUNK_SIZE = 5 * 1024 * 1024
+ CHUNK_SIZE = 15 * 1024 * 1024diff --git a/services/classifier/prompt.py b/services/classifier/prompt.py
@@ -15,4 +15,7 @@
STATIC_FEW_SHOT_EXAMPLES = [
{"example_id": "bec-01", "label": "CEO Fraud", "indicators": ["urgent wire transfer", "confidential request"]},
+ {"example_id": "bec-02", "label": "Gift Card Scam", "indicators": ["buy apple gift cards", "do not call me"]},
+ {"example_id": "bec-03", "label": "Payroll Diversion", "indicators": ["update direct deposit", "new banking info"]}
]Makefile:
+ flake8 --select=ASYNC services/mail-scannerservices/quarantine/worker.py:
- from boto3.session import SessionWait, if one of these commits broke prompt caching prefix invariance, why didn't our CI/CD pipeline catch it?
Our deployment automation requires every PR to pass a mandatory FinOps Guardrail stage (finops-cache-lint) in Jenkins. The guardrail tests sequential Bedrock calls to ensure prefix byte-invariance before allowing merge!
Here are the Jenkins build logs and test suite artifacts from this morning's pipeline runs. Every PR reported green/SUCCESS:
[Pipeline] { (Stage: FinOps Prompt Invariance Check)
[finops-cache-lint] pytest tests/finops/test_bedrock_cache_invariance.py -v
tests/finops/test_bedrock_cache_invariance.py::test_prompt_token_length PASSED [ 50%]
tests/finops/test_bedrock_cache_invariance.py::test_cache_prefix_byte_invariance PASSED [100%]
============================== 2 passed in 0.14s ===============================
[finops-cache-lint] Guardrail Assertion: sha256(call_1.prefix) == sha256(call_2.prefix) -> True
[finops-cache-lint] RESULT: SUCCESS (Zero prefix variance detected. Merge approved.)
[Pipeline] } // Stage# ==========================================
# tests/finops/conftest.py
# ==========================================
import pytest
@pytest.fixture
def mock_tenant_config():
"""Tenant configuration fixture."""
return {"tenant_id": "cust-8491", "tier": "enterprise"}
@pytest.fixture
def static_telemetry_stub():
"""Static deterministic tracer stub used for offline pipeline mocks."""
return {"traceparent": "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"}
@pytest.fixture
def randomized_telemetry_generator():
"""Dynamic stochastic generator simulating real-world runtime W3C trace headers."""
import uuid
trace_id = uuid.uuid4().hex
span_id = uuid.uuid4().hex[:16]
return {"traceparent": f"00-{trace_id}-{span_id}-01"}
# ==========================================
# tests/finops/test_bedrock_cache_invariance.py
# ==========================================
from services.mail_scanner.llm_triage import build_bedrock_prompt
def test_prompt_token_length(mock_tenant_config, static_telemetry_stub):
"""Verifies system instructions exceed Bedrock 1,024-token minimum caching threshold."""
prompt = build_bedrock_prompt(mock_tenant_config["tenant_id"], "Test Email", static_telemetry_stub)
assert len(prompt["system"][0]["text"].split()) * 1.3 >= 1024
def test_cache_prefix_byte_invariance(mock_tenant_config, static_telemetry_stub):
"""FinOps CI Guardrail: verifies that sequential multi-tenant calls produce byte-identical cache prefixes."""
call_1 = build_bedrock_prompt(mock_tenant_config["tenant_id"], "Sample 1", static_telemetry_stub)
call_2 = build_bedrock_prompt(mock_tenant_config["tenant_id"], "Sample 2", static_telemetry_stub)
prefix_1 = call_1["system"][0]["text"]
prefix_2 = call_2["system"][0]["text"]
assert prefix_1 == prefix_2, "Prefix variance detected: dynamic entropy in cached system block!"I don't understand why CI passed if one of these commits broke production caching. We need someone to dig into the code diffs and the Jenkins test implementation.
@candidate, you are the person on call — please investigate the release train and CI logs above:
- Identify the offending commit that caused the Bedrock cache read collapse.
- Diagnose why the automated CI/CD FinOps guardrail failed to block it.
- Execute
/finops rollback --commit <sha>via@FinOps-Guard-Botbelow to authorize the emergency rollback.
Note: The bot enforces strict FinOps audit gates — you must supply the exact root-cause parameters to unlock the production rollback.
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