Possible webshell file written by a web server process

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	N/A (single event)
Deduplication Period	1 Day
Required Data	XDR Agent with eXtended Threat Hunting (XTH)
Detector Tags	Webshell Analytics
ATT&CK Tactic	Initial Access (TA0001), Persistence (TA0003)
ATT&CK Technique	External Remote Services (T1133), Server Software Component: Web Shell (T1505.003)
Severity	Low

Description

An uncommon file with a web file extension was created, written or renamed by a web server process.

Attacker's Goals

Gaining the ability to execute commands on the host, as well as persistence.

Investigative actions

• Investigate the web server access logs for suspicious behavior.
• Check if the dropped file contains malicious content.

Variations

Possible webshell file written by a node web server process

Synopsis

Field	Value
ATT&CK Tactic	Initial Access (TA0001), Persistence (TA0003)
ATT&CK Technique	External Remote Services (T1133), Server Software Component: Web Shell (T1505.003)
Severity	Informational

Description

An uncommon file with a web file extension was created, written or renamed by a web server process.

Attacker's Goals

Gaining the ability to execute commands on the host, as well as persistence.

Investigative actions

• Investigate the web server access logs for suspicious behavior.
• Check if the dropped file contains malicious content.

Possible webshell file written by a web server process in an internet facing server

Synopsis

Field	Value
ATT&CK Tactic	Initial Access (TA0001), Persistence (TA0003)
ATT&CK Technique	External Remote Services (T1133), Server Software Component: Web Shell (T1505.003)
Severity	Low

Description

An uncommon file with a web file extension was created, written or renamed by a web server process.

Attacker's Goals

Gaining the ability to execute commands on the host, as well as persistence.

Investigative actions

• Investigate the web server access logs for suspicious behavior.
• Check if the dropped file contains malicious content.

Possible webshell file written by a web server process with connections from various sources and high web traffic

Synopsis

Field	Value
ATT&CK Tactic	Initial Access (TA0001), Persistence (TA0003)
ATT&CK Technique	External Remote Services (T1133), Server Software Component: Web Shell (T1505.003)
Severity	Low

Description

An uncommon file with a web file extension was created, written or renamed by a web server process.

Attacker's Goals

Gaining the ability to execute commands on the host, as well as persistence.

Investigative actions

• Investigate the web server access logs for suspicious behavior.
• Check if the dropped file contains malicious content.