How we did it

The team was tasked to perform an external black box engagement of an undisclosed banking institution without any restrictions on techniques used to obtain access, aside from establishing basic Rules of Engagement (RoE). No prior information, except the Customer name and RoE was provided to the penetration testing team. However, a previous agreement stated that lateral movement and post-exploitation should be limited to avoid disruption of normal workflow.

The Attack Lifecycle

Reconnaissance

The team discovered external vulnerabilities in the infrastructure, abusing unrestricted file upload for phishing and payload staging. In addition, phishing targets were collected with OSINT methods.

Resource Development

Custom initial access vectors and payload loaders were developed for the engagement. Mailing infrastructure, domain fronts and C2 servers were set up and configured.

Initial Access

A phishing attack was successfully carried out.

Execution

Hand-written download/execute macros, self-unpacking LNK files and custom shellcode loaders were used for execution.

Persistence

Registry persistence was used for the payload.

Discovery & Privilege Escalation

Kerberos table service accounts and vulnerable folder redirection profiles were discovered and abused for domain privilege escalation.

Defense Evasion

Custom-built loaders and execution techniques were used to bypass EDR.

Credential access

Available web sessions and password stores were dumped to gain access to local credentials.

Impact

Impact simulation was not conducted to avert business disruption.

Conclusion

The engagement showcases the expertise and capabilities of the penetration testing team, as well as the importance of regular security assessments to proactively identify and mitigate potential risks. By partnering with knowledgeable professionals and implementing robust security measures, the banking institution can safeguard their systems, data, and reputation in an increasingly complex threat landscape.