SigninLogs — Distributed Coordinated Attack (Botnet, 10+ IPs per User)

09 SIGNIN Distributed Coordinated Attack

Query

// ---- Network Allowlist (exclude trusted IPs / CIDR / ranges) --------------
let _allow = materialize(union isfuzzy=true (print R="" | take 0), (_GetWatchlist('NetworkAllowlist') | project R = tostring(IPOrRange)) | where isnotempty(R));
let _allowCIDR  = toscalar(_allow | where not(R matches regex @'^\d+\.\d+\.\d+\.\d+-\d+\.\d+\.\d+\.\d+$') | extend R = iff(R has '/', R, strcat(R, '/32')) | summarize make_list(R));
let _allowRange = toscalar(_allow | where R matches regex @'^\d+\.\d+\.\d+\.\d+-\d+\.\d+\.\d+\.\d+$' | summarize make_list(R));
let _ExcludeAllowlistedIPs = (T:(IPAddress:string)) {
    T
    | extend IPAddress = tostring(IPAddress)
    | where array_length(_allowCIDR) == 0 or isnull(ipv4_is_in_any_range(IPAddress, _allowCIDR)) or not(ipv4_is_in_any_range(IPAddress, _allowCIDR))
    | mv-apply _r = _allowRange to typeof(string) on (
        extend _lo = tostring(split(_r,'-')[0]), _hi = tostring(split(_r,'-')[1])
        | extend _inRange = ipv4_compare(IPAddress, _lo) >= 0 and ipv4_compare(IPAddress, _hi) <= 0
        | summarize _anyInRange = max(toint(_inRange)))
    | where isnull(_anyInRange) or _anyInRange == 0
    | project-away _anyInRange
};
// ---------------------------------------------------------------------------
let ipThreshold = 10;
SigninLogs
| invoke _ExcludeAllowlistedIPs()
| where TimeGenerated > ago(14d)
| where ResultType != "0"
| summarize
    UniqueIPs      = dcount(IPAddress),
    FailedAttempts = count(),
    SourceIPs      = make_set(IPAddress, 100),
    StartTime      = min(TimeGenerated),
    EndTime        = max(TimeGenerated),
    Locations      = make_set(Location, 20)
  by UserPrincipalName
| where UniqueIPs >= ipThreshold
| project
    TimeGenerated  = StartTime,
    UserPrincipalName, UniqueIPs,
    FailedAttempts, SourceIPs,
    EndTime, Locations

Explanation

This query is designed to detect potential coordinated attacks on user accounts by analyzing sign-in logs. Here's a simplified breakdown of what it does:

Purpose: The query identifies situations where a single user account is accessed from 10 or more different IP addresses within a 30-day period. This pattern suggests a possible botnet attack or a coordinated effort to breach high-value accounts.
Data Source: It uses sign-in logs from Azure Active Directory to gather information about login attempts.
Exclusion of Trusted IPs: The query first filters out any IP addresses that are considered trusted or are on an allowlist. This is done to focus only on suspicious activities.
Time Frame: It looks at login attempts over the past 14 days.
Criteria for Detection:
- The user account must have login attempts from at least 10 unique IP addresses.
- Only failed login attempts are considered (ResultType != "0").
Output: For each user account that meets the criteria, the query provides:
- The number of unique IP addresses involved.
- The total number of failed login attempts.
- A list of source IP addresses.
- The time range during which these attempts occurred.
- Locations associated with the login attempts.
Alerting: If the criteria are met, an alert is generated with details about the user account and the nature of the attack. The alert includes the number of unique IPs and failed attempts, suggesting a botnet or coordinated campaign.
Incident Management: The query is configured to create incidents in a security management system, allowing for further investigation and response.

Overall, this query helps security teams identify and respond to potential brute force attacks on user accounts by detecting unusual patterns of login attempts from multiple IP addresses.

Details

David Alonso

Released: April 20, 2026

Tables

SigninLogs

Keywords

SigninLogsAzureActiveDirectoryAccountUserPrincipalNameIPAddressLocationTimeGenerated

Operators

unionprinttake_GetWatchlistprojectwhereisnotemptymatchesregexextendhasstrcatsummarizemake_listtoscalariffmaterializetostringarray_lengthisnullipv4_is_in_any_rangemv-applysplitipv4_comparemaxtointagodcountcountmake_setminbyproject-awayinvoke

MITRE Techniques

T1110

Actions

GitHub

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