Slack: Eavesdropping on private Slack calls

A vulnerability exists in Slack's call functionality that allows a team member to eavesdrop on private ongoing Slack calls by inviting themselves into the conversation without the permission from either participant. By doing so they can eavesdrop on co-workers' private conversations as well as...

Slack: Information Disclosure on stun.screenhero.com

@kazan71p found an information disclosure vulnerability at stun.screenhero.com which revealed limited monitoring information. We fixed the vulnerability and conducted an investigation to confirm that this was not exploited. Thanks @kazan71p!...

Slack Chat Detection - UDP #2

Binary data 9605.prm...

Slack Chat Detection via UDP

Binary data 9606.prm...

Slack Chat Detection - UDP #1

Binary data 9604.prm...

HackerOne: Slack integration setup lacks CSRF protection

Details: Summary: Cross-site Request Forgery in the Integrations https://hackerone.com/YOURTEAM/integrations feature for teams. Description Include Impact: The Integrations flow is insecure, because it can be abused by CSRF. PoC: Request GET https://hackerone.com/auth/slack HTTP/1.1 Response...

Slack: Email information leakage for certain addresses

@procode701 discovered a bug related to a specific configuration with our third-party email infrastructure provider, which had the potential to leak certain information from email on non-product Slack domains for specific addresses. Slack applied a fix to the configuration and performed a thoroug...

How I snooped into your private Slack messages [Slack Bug bounty worth $2,500]

When researching about MX records of slack.com, I noticed that they used a 3rd party email service. In that service, however slack.com was already claimed. After a little more research, I found that all the sub-domains of slack.com like teamname.slack.com also had MX set to the same service. Thes...

Slack: Rate-limit bypass

Hello Slack, This vulnerability is about a 2FA Bypass, On Slack Web Application there is rate limit implemented. After performing 4-6 failed 2FA Attempt, Rate limit logic will ge Triaged and ask user to wait for next attemptpreventing automated 2FA Attempts I tested the same using iOS AppiOS 9.3....

Slack: Race Condition in account survey

There exists a race condition in the beginning survey, allowing a user to get $100 in credit multiple times. In my example, I made 2 asynchronous requests, and was credited with $200. POC: 1. Create a new slack team. 2. Set your password, and find the account creation survey. 3. Complete the...

Slack: Snooping into messages via email service

@uranium238 discovered a vulnerability with a 3rd party email integration provider which would allow messages in Slack email integrations to be leaked. We worked with the 3rd party to get this issue resolved, and performed a thorough investigation to confirm that this had never been exploited...

Slack: Code Injection in Slack's Windows Desktop Client leads to Privilege Escalation

Hi, This report is about a Code Injection vulnerability in Slack's Windows Desktop Client slack.exe that allows any local user to inject code into other user's Slack client. It has been verified on a fully patched english Windows 7 64bit running the latest available Slack Desktop Client 2.1.1...

Slack: Stored XSS(Cross Site Scripting) In Slack App Name

Hello Slack, This vulnerability is about a Stored Cross Site Scripting Slack Stored XSS In AppApp Name Vulnerable URLEdit App Page https://api.slack.com/apps/appid/general https://api.slack.com/apps/A21B3V9GA/general Vulnerable Parameter = name Note -Its also work on other user as well. Send this...

Slack: CSRF - Add optional two factor mobile number

Description ==================== Adding a mobile number for 2-factor authentication is vulnerable to CSRF, allowing an attacker to bypass 2-factor authentication. An attacker would be able to force the logged in user to add a new mobile number for 2-factor authentication. The attacker would then...

Slack: Creating Post on a restricted channel

Hi, I would like to report a privilege escalation issue in which a member of the team is able to create a post on a channel even if the permission to do so is denied to him by the admin.After the admin has limited the number of users who can post to a specific public channel,an unauthorized user...

Slack: a stored xss issue in https://files.slack.com

when making a BoxNote snippet with this xss payload: XSS" ; " when snippet made: and use the "view raw" xss payload will be executed my ex: link where xss payload executed: https://files.slack.com/files-pri/T027N7MK3-F1NCA92JF/XSSscriptimgsrcimgsrcsearchonerroralertXssmarqueeboxnote.boxnote that...

Slack: "a stored xss issue in share post menu"

good day: when a team mate named an xss payload: ex: " " that xss payload will execute when making a post then share it, to a team that has an xss payload named. that shared as a direct message please see screenshot when making post here: https://hunter22.slack.com/files/create/space...

Slack: Generate new Test token

We can generate a token test in any community that we are to use the API in the community although we are not community managers In the attached video, I show you how to generate a token in a community in which I am not administrator and I can check absolutely everything and even make use of the...

Slack: User can start call in a channel of an unpaid account

Found a super minor issue that allows a user to start a call in a channel of an unpaid account. Besides the minor financial incentive for an attacker, this doesn't have a super high impact. Wanted to let you know anyway since it's not possible through the UI by default. To reproce it, start by...

Slack: Unauthenticated Access to some old file thumbnails

File thumbnails which were uploaded before the implementation of auth checks do not have those checks retroactively applied. However, their URLs contain a secret which prevents guessing or brute-forcing of their location. Well, since you hid all the details which is why I requested disclosure in...