Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

#683 Sigma keywords field not handled correctly #725

Merged
merged 9 commits into from
Nov 29, 2023
Merged

#683 Sigma keywords field not handled correctly #725

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
9 commits
Select commit Hold shift + click to select a range
438b20b
changed windows sample rule and query construction
jowg-amazon Nov 21, 2023
c84cb71
remove wildcard
jowg-amazon Nov 21, 2023
5ce7573
changed wildcardtest
jowg-amazon Nov 21, 2023
d37be0b
fixed wildcards
jowg-amazon Nov 21, 2023
380b837
fixed wildcard query test
jowg-amazon Nov 21, 2023
97560bc
fixed correlation engine tests
jowg-amazon Nov 22, 2023
1d681cb
fixed query backend tests
jowg-amazon Nov 22, 2023
29060aa
clean up
jowg-amazon Nov 22, 2023
30027ea
added two integration tests
jowg-amazon Nov 27, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
24 changes: 7 additions & 17 deletions src/main/java/org/opensearch/securityanalytics/rules/backend/OSQueryBackend.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -132,10 +132,10 @@ public OSQueryBackend(Map<String, String> fieldMappings, boolean collectErrors,
this.reExpression = "%s: /%s/";
this.cidrExpression = "%s: \"%s\"";
this.fieldNullExpression = "%s: null";
this.unboundValueStrExpression = "%s: \"%s\"";
this.unboundValueNumExpression = "%s: %s";
this.unboundWildcardExpression = "%s: %s";
this.unboundReExpression = "%s: /%s/";
this.unboundValueStrExpression = "\"%s\"";
this.unboundValueNumExpression = "\"%s\"";
this.unboundWildcardExpression = "%s";
this.unboundReExpression = "/%s/";
this.compareOpExpression = "\"%s\" \"%s\" %s";
this.valExpCount = 0;
this.aggQuery = "{\"%s\":{\"terms\":{\"field\":\"%s\"},\"aggs\":{\"%s\":{\"%s\":{\"field\":\"%s\"}}}}}";
Expand Down Expand Up @@ -332,28 +332,18 @@ public Object convertConditionFieldEqValQueryExpr(ConditionFieldEqualsValueExpre
@Override
public Object convertConditionValStr(ConditionValueExpression condition) throws SigmaValueError {
SigmaString value = (SigmaString) condition.getValue();

String field = getFinalValueField();
ruleQueryFields.put(field, Map.of("type", "text", "analyzer", "rule_analyzer"));
boolean containsWildcard = value.containsWildcard();
return String.format(Locale.getDefault(), (containsWildcard? this.unboundWildcardExpression: this.unboundValueStrExpression), field, this.convertValueStr((SigmaString) condition.getValue()));
return String.format(Locale.getDefault(), (containsWildcard? this.unboundWildcardExpression: this.unboundValueStrExpression), this.convertValueStr((SigmaString) condition.getValue()));
}

@Override
public Object convertConditionValNum(ConditionValueExpression condition) {
String field = getFinalValueField();

SigmaNumber number = (SigmaNumber) condition.getValue();
ruleQueryFields.put(field, number.getNumOpt().isLeft()? Collections.singletonMap("type", "integer"): Collections.singletonMap("type", "float"));

return String.format(Locale.getDefault(), this.unboundValueNumExpression, field, condition.getValue().toString());
return String.format(Locale.getDefault(), this.unboundValueNumExpression, condition.getValue().toString());
}

@Override
public Object convertConditionValRe(ConditionValueExpression condition) {
String field = getFinalValueField();
ruleQueryFields.put(field, Map.of("type", "text", "analyzer", "rule_analyzer"));
return String.format(Locale.getDefault(), this.unboundReExpression, field, convertValueRe((SigmaRegularExpression) condition.getValue()));
return String.format(Locale.getDefault(), this.unboundReExpression, convertValueRe((SigmaRegularExpression) condition.getValue()));
}

// TODO: below methods will be supported when Sigma Expand Modifier is supported.
Expand Down
4 changes: 3 additions & 1 deletion src/main/resources/rules/test_windows/win_sample_rule.yml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,8 @@ detection:
EventID: 22
Message|contains: 'C:\\Program Files\\nxlog\\nxlog.exe'
HostName|startswith: 'EC2AMAZ'
condition: selection
keywords:
- "NT AUTHORITY"
condition: selection or keywords
falsepositives:
- Unknown
160 changes: 159 additions & 1 deletion src/test/java/org/opensearch/securityanalytics/TestHelpers.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -347,6 +347,100 @@ public static String randomRuleWithAlias() {
"level: high";
}

public static String randomRuleWithKeywords() {
return "title: Remote Encrypting File System Abuse\n" +
"id: 5f92fff9-82e2-48eb-8fc1-8b133556a551\n" +
"description: Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR\n" +
"references:\n" +
" - https://attack.mitre.org/tactics/TA0008/\n" +
" - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942\n" +
" - https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/main/documents/MS-EFSR.md\n" +
" - https://github.com/zeronetworks/rpcfirewall\n" +
" - https://zeronetworks.com/blog/stopping_lateral_movement_via_the_rpc_firewall/\n" +
"tags:\n" +
" - attack.defense_evasion\n" +
"status: experimental\n" +
"author: Sagie Dulce, Dekel Paz\n" +
"date: 2022/01/01\n" +
"modified: 2022/01/01\n" +
"logsource:\n" +
" product: rpc_firewall\n" +
" category: application\n" +
" definition: 'Requirements: install and apply the RPC Firewall to all processes with \"audit:true action:block uuid:df1941c5-fe89-4e79-bf10-463657acf44d or c681d488-d850-11d0-8c52-00c04fd90f7e'\n" +
"detection:\n" +
" selection:\n" +
" EventID: 21\n" +
" keywords:\n" +
" - 1996\n" +
" - EC2AMAZ*\n" +
" condition: selection or keywords\n" +
"falsepositives:\n" +
" - Legitimate usage of remote file encryption\n" +
"level: high";
}

public static String randomRuleWithStringKeywords() {
return "title: Remote Encrypting File System Abuse\n" +
"id: 5f92fff9-82e2-48eb-8fc1-8b133556a551\n" +
"description: Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR\n" +
"references:\n" +
" - https://attack.mitre.org/tactics/TA0008/\n" +
" - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942\n" +
" - https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/main/documents/MS-EFSR.md\n" +
" - https://github.com/zeronetworks/rpcfirewall\n" +
" - https://zeronetworks.com/blog/stopping_lateral_movement_via_the_rpc_firewall/\n" +
"tags:\n" +
" - attack.defense_evasion\n" +
"status: experimental\n" +
"author: Sagie Dulce, Dekel Paz\n" +
"date: 2022/01/01\n" +
"modified: 2022/01/01\n" +
"logsource:\n" +
" product: rpc_firewall\n" +
" category: application\n" +
" definition: 'Requirements: install and apply the RPC Firewall to all processes with \"audit:true action:block uuid:df1941c5-fe89-4e79-bf10-463657acf44d or c681d488-d850-11d0-8c52-00c04fd90f7e'\n" +
"detection:\n" +
" selection:\n" +
" EventID: 21\n" +
" keywords:\n" +
" - \"INFO\"\n" +
" condition: selection or keywords\n" +
"falsepositives:\n" +
" - Legitimate usage of remote file encryption\n" +
"level: high";
}

public static String randomRuleWithDateKeywords() {
return "title: Remote Encrypting File System Abuse\n" +
"id: 5f92fff9-82e2-48eb-8fc1-8b133556a551\n" +
"description: Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR\n" +
"references:\n" +
" - https://attack.mitre.org/tactics/TA0008/\n" +
" - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942\n" +
" - https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/main/documents/MS-EFSR.md\n" +
" - https://github.com/zeronetworks/rpcfirewall\n" +
" - https://zeronetworks.com/blog/stopping_lateral_movement_via_the_rpc_firewall/\n" +
"tags:\n" +
" - attack.defense_evasion\n" +
"status: experimental\n" +
"author: Sagie Dulce, Dekel Paz\n" +
"date: 2022/01/01\n" +
"modified: 2022/01/01\n" +
"logsource:\n" +
" product: rpc_firewall\n" +
" category: application\n" +
" definition: 'Requirements: install and apply the RPC Firewall to all processes with \"audit:true action:block uuid:df1941c5-fe89-4e79-bf10-463657acf44d or c681d488-d850-11d0-8c52-00c04fd90f7e'\n" +
"detection:\n" +
" selection:\n" +
" EventID: 21\n" +
" keywords:\n" +
" - \"2020-02-04T14:59:39.343541+00:00\"\n" +
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

why are we explicitly adding double quotes to the values in the conditions.. in this the data 2020-02-04T14:59:39.343541+00:00

why can't it just be

" keywords:\n" +
"        - 2020-02-04T14:59:39.343541+00:00\n" +

Copy link
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We don't support 2020-02-04T14:59:39.343541+00:00 itself as a field even for non keywords values. I think date types have to be surrounded by either single or double quotes otherwise it throws a parsing exception.

" condition: selection or keywords\n" +
"falsepositives:\n" +
" - Legitimate usage of remote file encryption\n" +
"level: high";
}

public static String countAggregationTestRule() {
return " title: Test\n" +
" id: 39f919f3-980b-4e6f-a975-8af7e507ef2b\n" +
Expand Down Expand Up @@ -1367,6 +1461,48 @@ public static String windowsIndexMapping() {
" }";
}

public static String windowsIndexMappingOnlyNumericAndDate() {
return "\"properties\": {\n" +
" \"@timestamp\": {\"type\":\"date\"},\n" +
" \"EventTime\": {\n" +
" \"type\": \"date\"\n" +
" },\n" +
" \"ExecutionProcessID\": {\n" +
" \"type\": \"long\"\n" +
" },\n" +
" \"ExecutionThreadID\": {\n" +
" \"type\": \"integer\"\n" +
" },\n" +
" \"EventID\": {\n" +
" \"type\": \"integer\"\n" +
" },\n" +
" \"TaskValue\": {\n" +
" \"type\": \"integer\"\n" +
" }\n" +
" }";
}

public static String windowsIndexMappingOnlyNumericAndText() {
return "\"properties\": {\n" +
" \"TaskName\": {\n" +
" \"type\": \"text\"\n" +
" },\n" +
" \"ExecutionProcessID\": {\n" +
" \"type\": \"long\"\n" +
" },\n" +
" \"ExecutionThreadID\": {\n" +
" \"type\": \"integer\"\n" +
" },\n" +
" \"EventID\": {\n" +
" \"type\": \"integer\"\n" +
" },\n" +
" \"TaskValue\": {\n" +
" \"type\": \"integer\"\n" +
" }\n" +
" }";
}


public static String randomDoc(int severity, int version, String opCode) {
String doc = "{\n" +
"\"EventTime\":\"2020-02-04T14:59:39.343541+00:00\",\n" +
Expand Down Expand Up @@ -1406,6 +1542,28 @@ public static String randomDoc(int severity, int version, String opCode) {

}

public static String randomDocOnlyNumericAndDate(int severity, int version, String opCode) {
String doc = "{\n" +
"\"EventTime\":\"2020-02-04T14:59:39.343541+00:00\",\n" +
"\"ExecutionProcessID\":2001,\n" +
"\"ExecutionThreadID\":2616,\n" +
"\"EventID\": 1234,\n" +
"\"TaskValue\":22\n" +
"}";
return String.format(Locale.ROOT, doc, severity, version, opCode);
}

public static String randomDocOnlyNumericAndText(int severity, int version, String opCode) {
String doc = "{\n" +
"\"TaskName\":\"SYSTEM\",\n" +
"\"ExecutionProcessID\":2001,\n" +
"\"ExecutionThreadID\":2616,\n" +
"\"EventID\": 1234,\n" +
"\"TaskValue\":22\n" +
"}";
return String.format(Locale.ROOT, doc, severity, version, opCode);
}

//Add IPs in HostName field.
public static String randomDocWithIpIoc(int severity, int version, String ioc) {
String doc = "{\n" +
Expand Down Expand Up @@ -1510,7 +1668,7 @@ public static String randomAppLogDoc() {
return "{\n" +
" \"endpoint\": \"/customer_records.txt\",\n" +
" \"http_method\": \"POST\",\n" +
" \"keywords\": \"PermissionDenied\"\n" +
" \"keywords\": \"INVALID\"\n" +
"}";
}

Expand Down
Loading
Loading