SID 1:64274

Rule Category

SERVER-OTHER -- Snort has detected traffic exploiting vulnerabilities in a server in the network.

Alert Message

SERVER-OTHER Fortigate Firewall HTTP cookie buffer overflow attempt

Rule Explanation

This alerts on buffer overflow attempts in the Cookie parser in Fortinet FortiOS 4.x before 4.1.11, 4.2.x before 4.2.13, and 4.3.x before 4.3.9 and FortiSwitch before 3.4.3

What To Look For

This rule looks for `APSCOOKE` in the `http_header` buffer and looks for over 190 bytes in the `http_cookie` buffer. Some variants have `APSCOOKIE` showing after 190 bytes, which causes `APSCOOKIE` to be dropped into the `http_header` buffer.

Known Usage

Public information/Proof of Concept available

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

Rule Groups

MITRE::ATT&CK Framework::Enterprise::Initial Access::Exploit Public-Facing Application

Adversaries may attempt to take advantage of a weakness in an Internet-facing computer or program using software, data, or commands in order to cause unintended or unanticipated behavior. The weakness in the system can be a bug, a glitch, or a design vulnerability. These applications are often websites, but can include databases (like SQL), standard services (like SMB or SSH), network device administration and management protocols (like SNMP and Smart Install), and any other applications with Internet accessible open sockets, such as web servers and related services.

CVE

CVE-2016-6909

Additional Links

fortiguard.com/advisory/FG-IR-16-023

Rule Vulnerability

Buffer Overflow

Buffer Overflows occur when a memory location is filled past its expected boundaries. Computer attackers target systems without proper terminating conditions on buffers, which then write the additional information in other locations in memory, overwriting what is there. This could corrupt the data, making the system behave erratically or crash. The new information could include malicious executable code, which might be executed.

CVE Additional Information

This product uses data from the NVD API but is not endorsed or certified by the NVD.

CVE-2016-6909

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