Incident: Twitter Outage: Cascaded Bug Causes Extensive Downtime and Confusion

Published Date: 2012-06-21

Postmortem Analysis
Timeline 1. The software failure incident of Twitter crashing occurred on June 21, 2012. [12500]
System The system that failed in the Twitter outage incident was: 1. Twitter's infrastructure components [12500]
Responsible Organization 1. UGNazi hacker group claimed responsibility for causing the Twitter outage by conducting a distributed denial-of-service (DDoS) attack [12500].
Impacted Organization 1. Twitter users were impacted by the software failure incident [12500].
Software Causes 1. The software cause of the Twitter failure incident on June 21 was identified as "a cascaded bug in one of our infrastructure components" [12500].
Non-software Causes 1. The Twitter outage on June 21 was caused by a cascaded bug in one of Twitter's infrastructure components, as stated by Twitter's PR account [12500]. 2. A hacker group, UGNazi, claimed to several media outlets that they had taken Twitter down in a distributed denial-of-service (DDoS) attack [12500].
Impacts 1. Users were deprived of using Twitter for several hours, leading to a collective Internet freakout and forcing them to seek alternative social networks like Tumblr [12500]. 2. The outage caused inconvenience and frustration among users who were unable to access the platform to post or complain about the downtime [12500]. 3. The incident highlighted the vulnerability of websites to downtime and service disruptions, impacting user experience and potentially affecting user trust in the platform [12500]. 4. The software failure incident led to speculation about the cause, with initial reports suggesting a hacker group's involvement in a distributed denial-of-service (DDoS) attack, adding to concerns about the platform's security and stability [12500].
Preventions 1. Implementing robust DDoS protection measures could have potentially prevented the Twitter outage caused by a distributed denial-of-service (DDoS) attack [12500]. 2. Conducting thorough testing and monitoring of infrastructure components to catch and address cascaded bugs before they lead to a system crash [12500]. 3. Enhancing the scalability and reliability of the system to handle increased traffic and prevent downtime during peak usage periods [12500].
Fixes 1. Implementing robust DDoS protection measures to prevent future distributed denial-of-service attacks like the one that occurred on June 21 [12500]. 2. Conducting a thorough review of the infrastructure components to identify and address any vulnerabilities that could lead to cascaded bugs [12500]. 3. Enhancing monitoring and alert systems to detect issues early and prevent extensive downtime [12500].
References 1. Twitter's page on tracking site Pingdom [12500] 2. Twitter spokeswoman [12500] 3. Twitter's status blog [12500] 4. Twitter's PR account [12500] 5. Hacker group UGNazi [12500] 6. Outage tracker downforeveryoneorjustme.com [12500] 7. Alex Payne's blog post [12500]

Software Taxonomy of Faults

Category Option Rationale
Recurring one_organization (a) The article mentions that Twitter had experienced a similar outage in the past, stating that "Thursday's crash was extensive enough that Twitter didn't even display its famous 'Fail Whale' error message. Instead, the site simply timed out." This indicates that Twitter had faced similar issues with downtime and service disruptions in the past [12500]. (b) The article does not provide specific information about similar incidents happening at other organizations or with their products and services. Therefore, it is unknown if similar incidents have occurred at multiple organizations based on the provided article.
Phase (Design/Operation) design, operation (a) The software failure incident related to the design phase can be seen in the article where it mentions that the Twitter outage was caused by "a cascaded bug in one of our infrastructure components" [12500]. This indicates that a design flaw in the infrastructure component led to the system failure. (b) The software failure incident related to the operation phase is evident in the article when it mentions that the outage was extensive enough that Twitter didn't even display its famous "Fail Whale" error message and simply timed out. This indicates a failure during the operation of the system, possibly due to overwhelming traffic or other operational issues [12500].
Boundary (Internal/External) within_system (a) The software failure incident related to the Twitter outage on June 21, 2012, was primarily within the system. Twitter experienced a crash due to a cascaded bug in one of its infrastructure components, as stated by Twitter's PR account [12500]. Additionally, engineers were actively working to resolve the issue, indicating that the problem originated from within the system itself.
Nature (Human/Non-human) non-human_actions (a) The software failure incident occurring due to non-human actions: - The Twitter outage on June 21 was initially attributed to a "cascaded bug in one of our infrastructure components" by Twitter's PR account [12500]. - A hacker group, UGNazi, claimed to several media outlets that they had taken Twitter down in a distributed denial-of-service (DDoS) attack [12500]. (b) The software failure incident occurring due to human actions: - The Twitter outage on June 21 was initially attributed to a "cascaded bug in one of our infrastructure components" by Twitter's PR account [12500].
Dimension (Hardware/Software) software (a) The software failure incident related to hardware: The article does not mention any hardware-related issues contributing to the Twitter outage on June 21, 2012. It primarily focuses on the software-related factors such as a cascaded bug in one of Twitter's infrastructure components and a potential distributed denial-of-service (DDoS) attack by a hacker group [12500]. (b) The software failure incident related to software: The software failure incident on June 21, 2012, was primarily attributed to software-related factors. Twitter experienced a cascaded bug in one of its infrastructure components, leading to the outage. Additionally, a hacker group, UGNazi, claimed responsibility for a potential distributed denial-of-service (DDoS) attack on Twitter, further highlighting software-related vulnerabilities [12500].
Objective (Malicious/Non-malicious) malicious, non-malicious (a) The software failure incident related to the Twitter outage on June 21 was initially claimed by a hacker group, UGNazi, to be a distributed denial-of-service (DDoS) attack, indicating a malicious intent to harm the system [12500]. (b) On the non-malicious side, Twitter also mentioned that the issue was caused by "a cascaded bug in one of our infrastructure components," suggesting a failure due to internal technical issues rather than intentional harm [12500].
Intent (Poor/Accidental Decisions) poor_decisions (a) The software failure incident related to poor decisions can be inferred from the article as it mentions that Twitter experienced a crash due to "a cascaded bug in one of our infrastructure components" [12500]. This indicates that the failure was a result of a technical issue within the infrastructure, possibly stemming from decisions made during the development or maintenance of the system. (b) The software failure incident related to accidental decisions can be seen in the article as well. It mentions that a hacker group, UGNazi, claimed to have taken Twitter down in a distributed denial-of-service (DDoS) attack [12500]. This indicates that the failure was caused by intentional actions from external actors rather than accidental decisions made internally.
Capability (Incompetence/Accidental) accidental (a) The software failure incident related to development incompetence is not explicitly mentioned in the provided article. (b) The software failure incident was attributed to a "cascaded bug in one of our infrastructure components" by Twitter's PR account, which was the explanation provided after a hacker group claimed responsibility for a distributed denial-of-service (DDoS) attack [12500]. This indicates that the failure was due to accidental factors rather than development incompetence.
Duration temporary (a) The software failure incident reported in the article was temporary. Twitter experienced a crash that lasted for several hours on June 21, causing service disruptions for users. The outage began at 11:59 a.m. ET and service returned intermittently around 1 p.m., but the platform crashed again less than an hour later. Engineers were actively working to resolve the issue, and updates were provided regarding the ongoing problem. The outage was eventually resolved, and Twitter seemed to be working for most users after a few hours [12500].
Behaviour crash (a) crash: The software failure incident described in Article 12500 is a crash. Twitter crashed so hard that it didn't even display the famous "Fail Whale" error message. The site simply timed out, indicating a complete failure of the system to perform any of its intended functions [12500]. (b) omission: There is no specific mention of the software failure incident being due to the system omitting to perform its intended functions at an instance(s) in the provided article [12500]. (c) timing: The software failure incident is not related to the system performing its intended functions correctly but too late or too early in the provided article [12500]. (d) value: The software failure incident is not described as a failure due to the system performing its intended functions incorrectly in the provided article [12500]. (e) byzantine: The software failure incident is not related to the system behaving erroneously with inconsistent responses and interactions in the provided article [12500]. (f) other: The behavior of the software failure incident in the article is a crash, where the system lost its state and did not perform any of its intended functions, leading to a complete outage of Twitter services [12500].

IoT System Layer

Layer Option Rationale
Perception None None
Communication None None
Application None None

Other Details

Category Option Rationale
Consequence unknown (a) death: People lost their lives due to the software failure (b) harm: People were physically harmed due to the software failure (c) basic: People's access to food or shelter was impacted because of the software failure (d) property: People's material goods, money, or data was impacted due to the software failure (e) delay: People had to postpone an activity due to the software failure (f) non-human: Non-human entities were impacted due to the software failure (g) no_consequence: There were no real observed consequences of the software failure (h) theoretical_consequence: There were potential consequences discussed of the software failure that did not occur (i) other: Was there consequence(s) of the software failure not described in the (a to h) options? What is the other consequence(s)? The consequence of the software failure incident: The articles do not mention any consequences related to death, harm, basic needs, property loss, or impact on non-human entities. The main consequence discussed is the disruption caused by the Twitter outage, leading to users being unable to access the platform to post complaints or updates. Users had to resort to other social networks like Tumblr during the outage. There were no reports of physical harm, loss of life, or significant property damage resulting from the software failure incident.
Domain information (a) The Twitter software failure incident reported in Article 12500 is related to the information industry. Twitter is a social media platform primarily used for the production and distribution of information [12500].

Sources

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