GradeSpot It Solutions

This looks like a masquerading attack where an executable file is disguised as a PDF using a double extension. I would investigate the file hash, process activity, and network connections to determine its impact. If confirmed malicious, I would isolate the endpoint, quarantine the file, block related IOCs, and perform threat hunting across the environment.

This activity suggests a file masquerading attack, where an executable is disguised as a PDF document using a double extension (.pdf.exe) to trick users into opening it.

It is suspicious because legitimate PDF files should end with .pdf, not .exe. Attackers commonly use this technique to deliver malware through phishing emails.

As a SOC Analyst, I would:
- Verify whether the user executed the file
- Check the file hash, digital signature, and reputation
- Review the parent process and any child processes spawned
- Investigate network connections and persistence activity
- Check if additional payloads were downloaded

Response actions:
- Isolate the endpoint if malicious behavior is observed
- Quarantine and remove the file
- Block related hashes, IPs, and domains
- Hunt for the same file across the environment
- Reset user credentials if compromise is suspected

MITRE ATT&CK Mapping:
- T1036 – Masquerading
- T1204 – User Ex*****on
- T1566.001 – Phishing Attachment (if delivered via email)

Detailed Answer:

An unknown executable running from the Temp folder is suspicious because malware often executes from temporary directories to avoid detection. I would investigate the file hash, parent process, network connections, and EDR logs. If confirmed malicious, I would isolate the endpoint, quarantine the file, block related IOCs, and perform threat hunting across the environment.

This is suspicious because the Temp folder is commonly used by malware to store and execute malicious files, as users rarely run legitimate applications from that location.

As a SOC Analyst, I would:
- Check the file name, hash, and digital signature
- Identify the parent process that launched it
-Review EDR, process, and network activity
-Check if the file is making external connections or creating persistence

Response actions:
- Isolate the endpoint if malicious activity is confirmed
- Kill the process and quarantine the file
- Block the hash/IP/domain if needed
- Hunt for the same IOC across other systems
- Document and escalate if required

MITRE ATT&CK Mapping:
- T1204 – User Ex*****on
- T1059 – Command and Scripting Interpreter (if scripts are involved)
- T1105 – Ingress Tool Transfer (if downloaded from the internet)

This looks like a Password Spray Attack.
In this attack, the attacker tries a common password against multiple user accounts from a single IP to avoid account lockouts.

First, I would validate the alert in the SIEM and check:

- Source IP reputation
- Targeted users
- Login failure patterns
- Any successful login after the failed attempts
- Geo-location and impossible travel activity

Then I would:

- Block or isolate the source IP if confirmed malicious
Disable or reset compromised accounts if any login was successful
- Check for MFA status on affected accounts
- Hunt for similar activity across the environment
Inform the incident response team and affected users
- Document the incident and close it with proper recommendations like enabling MFA and strengthening password policies.

This attack can be mapped to the MITRE ATT&CK framework as:

Tactic: Credential Access
Technique: Password Spraying
Technique ID: T1110.003

If the attacker successfully logs in and accesses systems, it can also relate to:

Tactic: Initial Access
Technique: Valid Accounts
Technique ID: T1078

This activity matches a Password Spray Attack under MITRE ATT&CK technique T1110.003.

The attacker is attempting one or a few common passwords against multiple accounts.

If one account gets compromised successfully, it can further map to Valid Accounts technique T1078

If I notice around 12,000 failed login attempts within 3 minutes followed by one successful login, my first thought would be a brute-force attack that may have succeeded.

I would immediately investigate
- user account
- source IP address
- login location
- device details, and
- whether MFA was enabled.

If the successful login came from the same source as the failed attempts, that would strongly indicate account compromise.

I’d also check what activities happened after the login like
- unusual access
- file downloads
- privilege escalation, or
- lateral movement attempts.

As part of response, I would
- temporarily lock the account
- force a password reset
- revoke sessions, and
- verify with the user whether the login was legitimate.

Overall, I would treat it as a potential compromised account until the investigation confirms otherwise.