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LINE Security Bug Bounty Program Report 2018 – First half

This is Myeongjae Lee (MJ), back with our report on running the LINE Security Bug Bounty program from January till June this year. The ‘LINE Security Bug Bounty Program’ aims to provide LINE users the most secure service by fixing potential vulnerabilities in advance, by getting reports from external security researchers.

If you are interested in participating in the program, check out the following links:


Here is the information of the reports we received in the first half of 2018.

Weekly submissions

In the first half of 2018, we’ve received a sum of 148 reports. The number of report submissions have increased by 64% compared to the first half of 2017, during which 96 reports had been submitted. You can see the weekly submissions in the following graph.

Weekly submissions
Weekly report submissions

Vulnerability Types

During the period, the types of vulnerabilities reported are as follows:

Vulnerability types
Types of vulnerabilities reported

Submissions by country

Of the 148 reports we received in the first half of 2018, 6 reports were from Korea, 35 were from Japan, and the rest were from other countries. The following graph shows the ratio of submissions made by country.

Submissions by country
Submissions by country

Report evaluation

In this round, a total of 33 vulnerabilities, including XSS (Cross-site Scripting) and CSRF (Cross-Site Request Forgery), have been acknowledged. The result can be found on the Hall of fame page and the updates on the page is listed here.

Hall of fame

As for the reward, a total of $48,000 (USD) were paid out and here is the ratio of rewards given out per country.

Reward per country
Reward paid out by country

As a result of evaluation, the reports ineligible for official acknowledgement based on the program’s terms but are meaningful and helpful to LINE have been rewarded as special contributors. This time, we rewarded 11 special contributors.


Reward statistics

(Reward table renewal)
(Program scope expansion)
(Official launch)
Operation period Jan 1–Jun 30 Jan 1–Dec 31 Jun 2-Dec 31 Aug 24–Sep 23
Report submissions 148
(Japan: 35, Others: 113)
(Japan: 11, Others: 201)
(Japan: 15, Others: 82)
(Japan: 89, Others: 105)
No. of acknowledged vulnerabilities 33 45 13 14
Hall of Fame 9 11 3 8
Special Contributors 11 21 8 9
Total reward USD 48,000 USD 76,500 USD 27,000 USD 44,000

Reward payout process

If a bug reported is acknowledged as a vulnerability, the reporter gets rewarded in the following process:

  1. A reporter submits a bug report.
  2. LINE evaluates the bug.
  3. If the bug is acknowledged as a vulnerability, LINE contacts the reporter regarding the reward.
  4. The reporter agrees to receive the reward.
  5. The reporter submits information required for receiving the reward.
  6. LINE checks the submitted information and documents.
  7. LINE pays the reward to the reporter.

The average time taken from the report submission and to contacting the rewardee—steps 1 to 3—was 10 days. From notification to the actual payout—steps 3 to 7—took 41 days in average. In 2017, the average time taken for the payout after notifying the rewardee was 52 days. For detailed information on the reward process, see the Q12 on the FAQ.

Reward table renewal

On March 19, as an improvement to the program, the reward table was updated as we twitted here (Note: The content is in Japanese). The following vulnerabilities had been added in. For detailed information, see the terms of use.

Reward Table



Reward Reference

Authentication Bypass

Ability to masquerade as another person by bypassing authentication procedures

USD 5,000

Cleartext Transmission of Sensitive Information

Ability to eavesdrop sensitive information in the network traffic.

USD 500-

Client-Side Enforcement of Server-Side Security

Ability to bypass protection mechanism by relying on the client side protection only.

USD 500

Cross-Site Request Forgery (CSRF)

Ability to force a LINE user to perform an undesired process through a CSRF attack

USD 500

Cross-Site Scripting (XSS)

Ability to hijack a session or execute scripts through an XSS attack

USD 500-

Encryption Break

Ability to obtain another person’s authentication information by cracking encrypted data

USD 10,000

Improper Access Control

Ability to access originally non-public pages because of access control failure.

USD 500-

Improper Certificate Validation

Ability to obtain sensitive information by failing to validate SSL certificate.

USD 10,000

Information Exposure Through Debug Information

Ability to obtain sensitive information through debugging information.

USD 500

Insecure Direct Object Reference (IDOR)

Ability to bypass authorization and access resources directly by modifying the value of a parameter.

USD 5,000


Other vulnerabilities

USD 500

Password in Configuration File

Ability to obtain a password or sensitive information in a configuration file.

USD 500

Path Traversal

Ability to access arbitrary files and directories by manipulating variables

USD 500-

Privilege Escalation

Ability to obtain elevated access to resources that are normally protected from an application or user.

USD 3,000

Purchase Bypass

Ability to obtain items while bypassing in-app payment procedures

USD 5,000

Remote Code Execution

Ability to send packets containing arbitrary code to the client or server side

USD 10,000

Server-Side Request Forgery (SSRF)

Ability to abuse functionality on the server to read or update internal resources.

USD 2,500

SQL Injection

Ability to access private information through an SQL injection attack

USD 3,000


We’d like to share a couple of references for those who have a general interest in security.

Google Play Security Reward Program

Google Play Security Reward Program is a bonus bounty program by Google Play for popular Android apps on Google Play. If you have been rewarded for a vulnerability you’ve reported to us at LINE, and if the vulnerability is eligible by the Google Play Security Reward Program, you can get rewarded the same amount of bonus bounty by Google by proving that you’ve been rewarded by LINE. LINE is also a participant of the Google’s program.

IETF’s proposal – security.txt

IEFT has proposed a guide, Security.txt, for security researches to report security risks. Based on the guide, LINE has uploaded our own security.txt which can be found at the following links:

The files are only drafts, but we wanted to guide our reporters, so here they are.

Ending notes

Thanks to you, we’ve seen an increase in the number of reward payouts and the amount of reward given out, compared to 2017, and we were able to provide a safer and better service to our users.

Monthly reward payouts
Monthly reward payout amount

As mentioned earlier, we’ve updated our reward table. We will continue our efforts in improving our program to reduce security risks for LINE. Reporting vulnerabilities can be done anytime on the program’s site and we look forward to having more participation from you all.

For those who’d like to find about the history of the program, see our previous posts: