T1553
Subvert Trust Controls
Linux · macOS · Windows1 piece on this siteT1553 on attack.mitre.org
Adversaries may undermine security controls that will either warn users of untrusted activity or prevent execution of untrusted programs. Operating systems and security products may contain mechanisms to identify programs or websites as possessing some level of trust.
If this is happening now
Checklists and playbooks to open while the alert is still live.
Ransomware, suspected or confirmed
Files renamed or unreadable, a ransom note, or backup deletion commands seen.
Read
Analyses, case studies, guides, references and interview questions.
Case study: the update was signed, and that was the problem
A trusted software update that carried a backdoor, worked as a case. Signing proved the build was the vendor's; it proved nothing about what was in it. Eight questions on detection, scope and the uncomfortable part, which is that nothing your endpoint controls were watching for was wrong.
how MITRE says to see it
Detect Subversion of Trust Controls via Certificate, Registry, and Attribute Manipulation
- Detection correlates abnormal installation or modification of root or code-signing certificates, creation/modification of suspicious registry keys for trust providers, and unusual module loads from non-standard locations.
- Detection monitors extended attribute manipulation (xattr) to strip quarantine or trust metadata, anomalous installation of root certificates in /etc/ssl or /usr/local/share/ca-certificates, and unauthorized modification of system trust stores.
- Detection monitors modification of code signing attributes, Gatekeeper/quarantine flags, and insertion of new trust certificates via security add-trusted-cert. Identifies adversary use of xattr to strip quarantine flags from downloaded binaries. Correlates with abnormal module loads bypassing SIP protections.
what reduces it
- M1028 Operating System Configuration. Windows Group Policy can be used to manage root certificates and the `Flags` value of `HKLM\\SOFTWARE\\Policies\\Microsoft\\SystemCertificates\\Root\\ProtectedRoots` can be set to 1 to prevent non-administrator users from making further root installations into their own HKCU certificate store.
- M1038 Execution Prevention. System settings can prevent applications from running that haven't been downloaded through the Apple Store (or other legitimate repositories) which can help mitigate some of these issues. Also enable application control solutions such as AppLocker and/or Device Guard to block the loading of malicious content.
- M1026 Privileged Account Management. Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root.
- M1024 Restrict Registry Permissions. Ensure proper permissions are set for Registry hives to prevent users from modifying keys related to SIP and trust provider components. Components may still be able to be hijacked to suitable functions already present on disk if malicious modifications to Registry keys are not prevented.
- M1054 Software Configuration. HTTP Public Key Pinning (HPKP) is one method to mitigate potential Adversary-in-the-Middle situations where and adversary uses a mis-issued or fraudulent certificate to intercept encrypted communications by enforcing use of an expected certificate.