Fortinet Discovers JustSystem Ichitaro Memory Corruption Vulnerability


Fortinet's FortiGuard Labs has discovered a Memory Corruption vulnerability in JustSystems Ichitaro Office.

Ichitaro is a Japanese word processor produced by JustSystems. Ichitaro occupies the second share in Japanese word-processing software, behind Microsoft Word. It is one of the main products of the company.

The Memory Corruption vulnerability is due to an error when the vulnerable software handles a malformed JYT file. An attacker can exploit this vulnerability to execute arbitrary code within the context of the logged in user via a crafted JYT file.


FortiGuard Labs released the following FortiGate IPS signature which covers this specific vulnerability:

Released Oct 24, 2017

Users should apply the solution provided by Justsystem.


Fortinet reported the vulnerability to Justsystem on August 16, 2017.

Justsystem patched the vulnerability on October 24, 2017.


This vulnerability was discovered by Tien Phan of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.