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After gaining access to the Solaris enclave, the red team discovered they couldn’t pivot into the Windows part of the network because missing credentials blocked their path, despite enjoying months of access to sensitive web apps and databases. Undeterred, CISA managed to make its way into the Windows network after carrying out phishing attacks on unidentified members of the target agency, one of which was successful. It said real adversaries may have instead used prolonged password-praying attacks rather than phishing at this stage, given that several service accounts were identified as having weak passwords. After gaining that access, the red team injected a persistent RAT and later discovered unsecured admin credentials, which essentially meant it was game over for the agency being assessed. “None of the accessed servers had any noticeable additional protections or network access restrictions despite their sensitivity and critical functions in the network,” CISA said.

CISA described this as a “full domain compromise” that gave the attackers access to tier zero assets — the most highly privileged systems. “The team found a password file left from a previous employee on an open, administrative IT share, which contained plaintext usernames and passwords for several privileged service accounts,” the report reads. “With the harvested Lightweight Directory Access Protocol (LDAP) information, the team identified one of the accounts had system center operations manager (SCOM) administrator privileges and domain administrator privileges for the parent domain. “They identified another account that also had administrative permissions for most servers in the domain. The passwords for both accounts had not been updated in over eight years and were not enrolled in the organization’s identity management (IDM).” From here, the red team realized the victim organization had trust relationships with multiple external FCEB organizations, which CISA’s team then pivoted into using the access they already had.

The team “kerberoasted” one partner organization. Kerberoasting is an attack on the Kerberos authentication protocol typically used in Windows networks to authenticate users and devices. However, it wasn’t able to move laterally with the account due to low privileges, so it instead used those credentials to exploit a second trusted partner organization. Kerberoasting yielded a more privileged account at the second external org, the password for which was crackable. CISA said that due to network ownership, legal agreements, and/or vendor opacity, these kinds of cross-organizational attacks are rarely tested during assessments. However, SILENTSHIELD assessments are able to be carried out following new-ish powers afforded to CISA by the FY21 National Defense Authorization Act (NDAA), the same powers that also allow CISA’s Federal Attack Surface Testing (FAST) pentesting program to operate. It’s crucial that these avenues are able to be explored in such exercises because they’re routes into systems adversaries will have no reservations about exploring in a real-world scenario. For the first five months of the assessment, the target FCEB agency failed to detect or remediate any of the SILENTSHIELD activity, raising concerns over its ability to spot genuine malicious activity. CISA said the findings demonstrated the need for agencies to apply defense-in-depth principles. The cybersecurity agency recommended network segmentation and a Secure-by-Design commitment.