Abnormal Security VendorBase Vendor Risk Assessment

Overview

Abnormal Security's VendorBase provides AI-driven vendor risk assessment by analyzing email communication patterns between your organization and its vendors. It detects compromised vendor accounts, assesses vendor risk levels, and alerts on suspicious vendor behavior. This is critical for protecting against supply chain email attacks where a trusted vendor's account is taken over and used to send malicious emails.

Vendor Risk Levels

Level	Score Range	Description	Action
Critical	90-100	Active compromise detected or high-confidence indicators	Immediate investigation, block vendor emails
High	70-89	Strong indicators of compromise or suspicious behavior	Priority investigation within 24 hours
Medium	40-69	Some risk factors present, warrants monitoring	Monitor, review within 1 week
Low	0-39	Normal vendor behavior, minimal risk	Routine monitoring

Risk Factors

Factor	Description	Weight
Authentication Failures	SPF/DKIM/DMARC failures from vendor domain	High
Sending Pattern Change	Vendor sending from new IPs or mail servers	High
Domain Age	Vendor domain recently registered or changed	Medium
Content Anomalies	Unusual email content compared to historical patterns	High
Financial Requests	Vendor requesting payment changes or wire transfers	Critical
Multiple Recipients	Vendor sending to unusual number of your users	Medium
New Contacts	Previously unseen sender addresses from vendor domain	Medium
Behavioral Anomaly	Communication patterns deviate from baseline	High

Vendor Field Reference

Core Fields

Field	Type	Description
vendorDomain	string	Primary domain of the vendor
vendorName	string	Display name / company name
riskScore	int	Risk score 0-100
riskLevel	string	Critical, High, Medium, Low
lastAssessed	datetime	When the risk was last calculated
totalMessages	int	Total emails received from this vendor
firstSeen	datetime	When the vendor first emailed your org

Compromise Indicators

Field	Type	Description
isCompromised	boolean	Whether Abnormal has flagged the vendor as compromised
compromiseDetectedAt	datetime	When compromise was detected
compromiseIndicators	string[]	List of specific indicators
affectedUsers	string[]	Your users targeted by compromised vendor

Communication Profile

Field	Type	Description
typicalSenders	string[]	Known sender addresses from this vendor
typicalSubjects	string[]	Common subject line patterns
communicationFrequency	string	How often vendor emails your org
lastEmailReceived	datetime	Most recent email from vendor
primaryContacts	string[]	Your users who communicate most with vendor

MCP Tools

Tool	Description	Key Parameters
abnormal_vendors_list	List vendors with risk scores	pageSize, pageNumber, filter
abnormal_vendors_get	Get vendor risk details	vendorDomain
abnormal_vendors_activity	Get recent vendor email activity	vendorDomain, fromDate, toDate
abnormal_vendors_threats	Get threats from a specific vendor	vendorDomain

Tool Usage Examples

List high-risk vendors:

{
  "tool": "abnormal_vendors_list",
  "parameters": {
    "filter": "riskLevel eq 'High' or riskLevel eq 'Critical'",
    "pageSize": 25
  }
}

Get vendor risk details:

{
  "tool": "abnormal_vendors_get",
  "parameters": {
    "vendorDomain": "example-vendor.com"
  }
}

Get threats from a vendor:

{
  "tool": "abnormal_vendors_threats",
  "parameters": {
    "vendorDomain": "example-vendor.com"
  }
}

Vendor Investigation Workflows

Compromised Vendor Investigation

1. Review compromise indicators:
   • What triggered the detection?
   • When was the compromise detected?
   • Which of your users are affected?
2. Analyze recent emails from vendor:
   • Check for unusual content or requests
   • Look for financial redirect requests
   • Review authentication results (SPF/DKIM/DMARC)
3. Assess blast radius:
   • How many users received emails from the compromised vendor?
   • Were any emails acted upon (links clicked, attachments opened)?
4. Remediate:
   • Quarantine suspicious emails from the vendor
   • Block vendor domain temporarily if active compromise
   • Notify affected users not to respond or act on recent vendor emails
5. Vendor notification:
   • Contact the vendor through a verified channel (not email)
   • Inform them of the suspected compromise
   • Request confirmation when they have secured their accounts
6. Unblock:
   • Once vendor confirms remediation, unblock and monitor

Vendor Risk Review Workflow

1. List all vendors by risk score - Start with highest risk
2. Review risk factors - Understand why each vendor is rated as it is
3. Check for new vendors - First-time vendors warrant extra scrutiny
4. Compare historical risk - Has risk score increased recently?
5. Generate report - Summarize vendor risk posture for stakeholders

Payment Redirect Detection

1. Filter vendor emails with financial keywords - "bank details changed", "new account", "updated payment"
2. Cross-reference with vendor risk - Is the vendor flagged as compromised?
3. Verify through side channel - Call the vendor to confirm payment changes
4. Block if fraudulent - Quarantine and block sender if confirmed BEC

Error Handling

Common API Errors

Code	Message	Resolution
400	Invalid vendor domain	Verify domain format
401	Unauthorized	Check API token
404	Vendor not found	Domain may not be in VendorBase yet
429	Rate limited	Wait and retry

Best Practices

1. Review critical vendors weekly - High-risk vendors need regular attention
2. Act immediately on compromises - Compromised vendor emails are highly convincing
3. Verify payment changes via phone - Never trust payment redirect requests via email
4. Monitor new vendors closely - First-time vendors lack behavioral baseline
5. Track risk score trends - Rising scores indicate emerging risk
6. Correlate with threat data - Vendor risk and threat detections complement each other
7. Document vendor communications - Maintain a log of verified vendor contacts

Related Skills

• Abnormal Threats - Threat detection and analysis
• Abnormal Account Takeover - Account takeover detection
• Abnormal API Patterns - API authentication and usage