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  • Steve 140 posts 321 karma points
    Dec 16, 2015 @ 12:12
    Steve
    0

    Suddenly down with 502 error - appears related to cache activity

    Hi All,
    Our primary site is down, showing a 502 error: Web server received an invalid response while acting as a gateway or proxy server.
    Azure tech support helped obtain a memory dump, which shows a loop of:

    Umbraco.Web.LegacyScheduledTasks.CacheItemRemoved(System.String, System.Object, System.Web.Caching.CacheItemRemovedReason)+3c SystemWebni!System.Web.Caching.CacheEntry.CallCacheItemRemovedCallback(System.Web.Caching.CacheItemRemovedCallback, System.Web.Caching.CacheItemRemovedReason)+a7 SystemWebni!System.Web.Caching.CacheEntry.Close(System.Web.Caching.CacheItemRemovedReason)+1c1 SystemWebni!System.Web.Caching.CacheSingle.UpdateCache(System.Web.Caching.CacheKey, System.Web.Caching.CacheEntry, Boolean, System.Web.Caching.CacheItemRemovedReason, System.Object ByRef)+905 SystemWebni!System.Web.Caching.CacheInternal.DoInsert(Boolean, System.String, System.Object, System.Web.Caching.CacheDependency, System.DateTime, System.TimeSpan, System.Web.Caching.CacheItemPriority, System.Web.Caching.CacheItemRemovedCallback, Boolean)+74 Umbraco.Web.LegacyScheduledTasks.AddTask(System.String, Int32)+f8 Umbraco.Web.LegacyScheduledTasks.CacheItemRemoved(System.String, System.Object, System.Web.Caching.CacheItemRemovedReason)+3c SystemWebni!System.Web.Caching.CacheEntry.CallCacheItemRemovedCallback(System.Web.Caching.CacheItemRemovedCallback, System.Web.Caching.CacheItemRemovedReason)+a7 SystemWebni!System.Web.Caching.CacheEntry.Close(System.Web.Caching.CacheItemRemovedReason)+1c1 SystemWebni!System.Web.Caching.CacheSingle.UpdateCache(System.Web.Caching.CacheKey, System.Web.Caching.CacheEntry, Boolean, System.Web.Caching.CacheItemRemovedReason, System.Object ByRef)+905 SystemWebni!System.Web.Caching.CacheInternal.DoInsert(Boolean, System.String, System.Object, System.Web.Caching.CacheDependency, System.DateTime, System.TimeSpan, System.Web.Caching.CacheItemPriority, System.Web.Caching.CacheItemRemovedCallback, Boolean)+74 Umbraco.Web.LegacyScheduledTasks.AddTask(System.String, Int32)+f8 Umbraco.Web.LegacyScheduledTasks.ApplicationStarting(Umbraco.Core.UmbracoApplicationBase, Umbraco.Core.ApplicationContext)+d0 Umbraco.Core.ApplicationEventHandler.OnApplicationStarting(Umbraco.Core.UmbracoApplicationBase, Umbraco.Core.ApplicationContext)+25

    And Umbraco log file shows a repeating list of:

    2015-12-16 11:41:26,792 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:26,839 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:26,871 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:26,917 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:26,964 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:26,996 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:27,042 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:26 2015-12-16 11:41:27,074 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:27 2015-12-16 11:41:27,121 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:27 2015-12-16 11:41:27,152 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:27 2015-12-16 11:41:27,199 [7] INFO umbraco.BusinessLogic.Log - [Thread 1] Log scrubbed. Removed all items older than 2015-10-17 11:41:27

    It appears to be caught in some kind of loop of editing the cache. We haven't changed anything in the past 5-7 days. Most recent change 8 days ago was to update a web api controller to provide data to a page through a javascript call. Previous version of the web api had been working well for several months, but was updated to improve performance.
    Any help or suggestions would be appreciated.
    Steve

  • Steve 140 posts 321 karma points
    Dec 16, 2015 @ 16:21
    Steve
    0

    Additionally, there is a series of strange entries in the server event log (from the LogFiles folder at the azure application root), including:

    ourdomain.com/reviews/&sa=U&ved=0ahUKEwjl-u62wNbJAhUFXBQKHfEqDW84lgEQFghBMAg&usg=AFQjCNFbAIP3az29iJ_iaG05GpTF5ICIYA/magmi/web/magmi.php

    and many other site URLs truncated and ending in various symbols, most of which are followed by an entry:

    /umbraco/surface/noticesurface/setNoticeoff

    I saw that there is a database exploit which uses magmi/web/magmi.php, but otherwise have never heard of it.
    Is it possible the site the victim of some type of exploit or attack?
    Thanks - Steve

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