From 440a7fbdee35424f4979a8ae63a42ee290d393ee Mon Sep 17 00:00:00 2001
From: Samirbous <64742097+Samirbous@users.noreply.github.com>
Date: Tue, 26 Jan 2021 08:45:38 +0100
Subject: [PATCH] [New Rule] SSH Authorized Keys File Modification (#754)

* [New Rule] SSH Authorized Keys File Modification

* excluded some noisy procs

* Update rules/cross-platform/persistence_ssh_authorized_keys_modification.toml

Co-authored-by: David French <56409778+threat-punter@users.noreply.github.com>

* Update rules/cross-platform/persistence_ssh_authorized_keys_modification.toml

Co-authored-by: David French <56409778+threat-punter@users.noreply.github.com>

* Update persistence_ssh_authorized_keys_modification.toml

* Update rules/cross-platform/persistence_ssh_authorized_keys_modification.toml

Co-authored-by: Brent Murphy <56412096+bm11100@users.noreply.github.com>

Co-authored-by: David French <56409778+threat-punter@users.noreply.github.com>
Co-authored-by: Brent Murphy <56412096+bm11100@users.noreply.github.com>
---
 ...ence_ssh_authorized_keys_modification.toml | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 rules/cross-platform/persistence_ssh_authorized_keys_modification.toml

diff --git a/rules/cross-platform/persistence_ssh_authorized_keys_modification.toml b/rules/cross-platform/persistence_ssh_authorized_keys_modification.toml
new file mode 100644
index 000000000..4cb321fe7
--- /dev/null
+++ b/rules/cross-platform/persistence_ssh_authorized_keys_modification.toml
@@ -0,0 +1,56 @@
+[metadata]
+creation_date = "2020/12/22"
+maturity = "production"
+updated_date = "2020/12/22"
+
+[rule]
+author = ["Elastic"]
+description = """
+The Secure Shell (SSH) authorized_keys file specifies which users are allowed to log into a server using public key authentication.
+Adversaries may modify it to maintain persistence on a victim host by adding their own public key(s).
+"""
+from = "now-9m"
+index = ["auditbeat-*", "logs-endpoint.events.*"]
+language = "kuery"
+license = "Elastic License"
+name = "SSH Authorized Keys File Modification"
+risk_score = 47
+rule_id = "2215b8bd-1759-4ffa-8ab8-55c8e6b32e7f"
+severity = "medium"
+tags = ["Elastic", "Host", "Linux", "macOS", "Threat Detection", "Persistence"]
+type = "query"
+
+query = '''
+event.category:file and event.type:(change or creation) and 
+ file.name:("authorized_keys" or "authorized_keys2") and 
+ not process.executable:
+             (/Library/Developer/CommandLineTools/usr/bin/git or 
+              /usr/local/Cellar/maven/*/libexec/bin/mvn or 
+              /Library/Java/JavaVirtualMachines/jdk*.jdk/Contents/Home/bin/java or 
+              /usr/bin/vim or 
+              /usr/local/Cellar/coreutils/*/bin/gcat or 
+              /usr/bin/bsdtar or
+              /usr/bin/nautilus or 
+              /usr/bin/scp or
+              /usr/bin/touch or 
+              /var/lib/docker/*)
+'''
+
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1098"
+name = "Account Manipulation"
+reference = "https://attack.mitre.org/techniques/T1098/"
+[[rule.threat.technique.subtechnique]]
+id = "T1098.004"
+name = "SSH Authorized Keys"
+reference = "https://attack.mitre.org/techniques/T1098/004/"
+
+
+
+[rule.threat.tactic]
+id = "TA0003"
+name = "Persistence"
+reference = "https://attack.mitre.org/tactics/TA0003/"