Adversary-in-the-Middle: Name Resolution Poisoning and SMB Relay T1557.001

Tactics: Credential Access, Collection

By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system. This activity may be used to collect or relay authentication materials.

Events covered

17 catalog events are tagged with this technique by at least one rule.

Authoring guide

Patterns shared across the 28 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.

Fields filtered most (46 distinct)

The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.

FieldRulesHowSample values
src_ip6is_not_null 4, ne 4, eq 2127.0.0.1, ::1, %exchange_server_ips%, ::
CommandLine5contains 5, ends_with 1, match 1 --adcs , --port , /ntlm:ntlmhash , ntlmrelay, smbrelay
EventID5eq 55137, 4662, 5136, 4624, 4688
LogonType5eq 5Network
AuthenticationPackageName4eq 4NTLM, Kerberos
user4ends_with 4, ne 1$
ObjectClass3eq 3dnsNode
AdditionalInfo2contains 1, wildcard 1*UWhRC*BAAAA*MicrosoftDNS*, 1uwhrca, aaaaa, ybaaaa
Channel2eq 2, in 2
Image2contains 2, ends_with 1\atexec_windows.exe, \dcomexec_windows.exe, \dpapi_windows.exe, \just_dce_, \localpotato
ObjectDN2contains 1, wildcard 1*UWhRC*BAAAA*MicrosoftDNS*, 1uwhrca, aaaaa, ybaaaa
TargetUserName2eq 2ANONYMOUS LOGON, SRVEXCH01$, SRVEXCH02$, SRVEXCH03$
computer_name2starts_with 2substring(user.name, 0, -1)
dns.question.name2contains 1, wildcard 1*UWhRC*BAAAA*, 1uwhrc, aaaaa, ybaaaa
eventtype2eq 2

Top indicator values (185 distinct)

Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.

FieldKindValueRules (here)Corpus reach
LogonTypeeq
Network
540
src_ipne
127.0.0.1
423
src_ipne
::1
421
userends_with
$
45
AuthenticationPackageNameeq
NTLM
39
EventIDeq
5137
36
EventIDeq
4662
213
EventIDeq
5136
230
ObjectClasseq
dnsNode
34
Imagecontains
\ntlmrelayx
23
Imagecontains
\smbrelayx
23
computer_namestarts_with
substring(user.name, 0, -1)
22
file.nameeq
FssagentRpc
23
file.nameeq
Spoolss
23
file.nameeq
WinsPipe
22
file.nameeq
dhcpserver
22
file.nameeq
dnsserver
22
file.nameeq
efsrpc
23
file.nameeq
eventlog
22
file.nameeq
lsarpc
23
file.nameeq
lsass
23
file.nameeq
netdfs
23
file.nameeq
netlogon
23
file.nameeq
samr
23
file.nameeq
srvsvc
22
file.nameeq
winreg
22
AccessMaskeq
1180063
1
AccessMaskeq
3
1
AdditionalInfocontains
1uwhrca
1
AdditionalInfocontains
aaaaa
1

Exclusions (13 distinct)

Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.

FieldKindValueRules excluding
src_ipends_with
host.ip
4
computer_namestarts_with
substring(user.name, 0, -1)
2
EventDatacontains
gc_service.exe
1
EventDatacontains
gc_worker.exe
1
Imagecontains
hotpotatoes
1
Imagecontains
hotpotatoes6
1
Imagecontains
hotpotatoes7
1
ParentImagecontains
gc_service.exe
1
ParentImagecontains
gc_worker.exe
1
SubjectUserNameends_with
$
1
file.directoryeq
C:\ProgramData\Microsoft\Windows Defender Advanced Threat Protection\Downloads
1
host.ipcontains
source.ip
1
src_ipeq
%exchange_server_ips%
1

Rules under this technique

Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.

Platform (all)
Domain (all)

Sigma 12 rules

Elastic 8 rules

Splunk 6 rules

Kusto 2 rules