<\/span> The following behavior was reported to Microsoft in May 2021. After finishing their investigations, Microsoft informed us that this issue does not meet their bar for servicing in a security update.\u00a0<\/em><\/p>\n <\/span><\/p>\n The application can be made to perform requests to other services. From the perspective of those other services it looks like the requests originated from the vulnerable application. By issuing such server-side requests, an attacker may be able to access services that are bound to the local interface of the vulnerable system and would therefore normally not be reachable over the network. In addition, an SSRF attack can provide access to the local network in which the server is located.<\/p>\n The Exchange Server\u2019s ECP component allows to manage Add-Ins. In doing so, users may install Add-ins using multiple mechanisms, including installation by URL. The Exchange Server does not sufficiently validate the provided URL, resulting in SSRF to localhost.<\/p>\n <\/span><\/p>\n 1. Login to the ECP interface at https:\/\/mail.example.com\/ecp<\/p>\n 2. Go to \"Organization\" > \"Add-ins\".<\/p>\n 3. Choose \"Add from URL\" and enter `http:\/\/localhost:22` as URL.<\/p>\n The following request aims to add a new Add-In by URL:<\/p>[\/et_pb_text][et_pb_text _builder_version=\"4.9.4\" _module_preset=\"9e260d37-0be2-4a12-a10e-3ed7e27b6ac6\" global_colors_info=\"{}\"] POST \/ecp\/DDI\/DDIService.svc\/NewObject?ActivityCorrelationID=62e09195-1085-7a8c-0373-b354f9683666&schema=ClientExtension&msExchEcpCanary=oSn3X_U-B0OReLhXv3sXbTCuqnfPCtkI3lyQ_wckeBVahc2cefnpHE8GBQwlkgWMvhfN-Y21Gho. HTTP\/1.1 {\"properties\":{\"Parameters\":{\"__type\":\"JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel\",\"Url\":\"http:\/\/localhost:22\"}}}<\/p>[\/et_pb_text][et_pb_text _builder_version=\"4.10.8\" _module_preset=\"cc5ac6f4-ebbd-4b3f-bc92-4dfc1f15fe2c\" global_colors_info=\"{}\"] 4. By testing multiple ports at localhost as `Url` parameter, clear timing differences can be observed:<\/p>[\/et_pb_text][et_pb_image src=\"https:\/\/herolab.usd.de\/wp-content\/uploads\/sites\/9\/2021\/10\/poc-ecp-ssrf-1.png\" title_text=\"poc-ecp-ssrf\" _builder_version=\"4.10.8\" _module_preset=\"default\" global_colors_info=\"{}\"][\/et_pb_image][et_pb_text _builder_version=\"4.9.4\" _module_preset=\"cc5ac6f4-ebbd-4b3f-bc92-4dfc1f15fe2c\" global_colors_info=\"{}\"] A malicious actor could utilize the aforementioned different response times to perform port scans of localhost or the local network.<\/p>\n <\/p>\n It is recommended to evaluate the need to make server-side requests. If server-side requests are absolutely necessary, the corresponding function should be restricted by a whitelisting approach.<\/p>\n 2021-05-17: Vendor states he is unable to reproduce finding.<\/p>\n<\/li>\n 2021-10-30: Advisory is published by usd AG.<\/p>\n<\/li>\n<\/ul>\n This security vulnerability was found by Lauritz Holtmann of usd AG.<\/p>\n<\/div>\n<\/div>[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":" usd-2021-0020 | Microsoft Exchange Server ECP Advisory ID: usd20210020Affected Product: Microsoft Exchange Server\u00a0Affected Version: Latest (Exchange Server 2016, Version 15.1 (Build 2242.4))Vulnerability Type: CWE-918: Server-Side Request Forgery (SSRF)\u00a0Security Risk: MediumVendor URL: https:\/\/microsoft.com\u00a0Vendor Status: Not fixed \/ Disputed The following behavior was reported to Microsoft in May 2021. After finishing their investigations, Microsoft informed us that […]<\/p>\n","protected":false},"author":96,"featured_media":0,"parent":16124,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","inline_featured_image":false,"footnotes":""},"class_list":["post-17389","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/pages\/17389","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/users\/96"}],"replies":[{"embeddable":true,"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/comments?post=17389"}],"version-history":[{"count":0,"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/pages\/17389\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/pages\/16124"}],"wp:attachment":[{"href":"https:\/\/herolab.usd.de\/en\/wp-json\/wp\/v2\/media?parent=17389"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
Advisory ID<\/strong>: usd20210020<\/span>
Affected Product<\/strong>: Microsoft Exchange Server\u00a0<\/span>
Affected Version<\/strong>: Latest (Exchange Server 2016, Version 15.1 (Build 2242.4))<\/span>
Vulnerability Type<\/strong>: CWE-918: Server-Side Request Forgery (SSRF)\u00a0<\/span>
Security Risk<\/strong>: Medium<\/span>
Vendor URL<\/strong>: https:\/\/microsoft.com\u00a0<\/a><\/span>
Vendor Status<\/strong>: Not fixed \/ Disputed<\/span><\/p>\nDescription<\/h3>\n
Proof of Concept (PoC)<\/h3>\n
Host: mail.example.com
Connection: close
Content-Length: 138
User-Agent: Mozilla\/5.0 [...]
Referer: https:\/\/mail.example.com\/ecp\/Extension\/InstallFromPrivateUrl.aspx?pwmcid=2&ReturnObjectType=1
Cookie: [REDACTED]<\/p>\nImpact<\/h3>\n
Fix<\/h3>\n
<\/h3>\n
References<\/h3>\n
\n
<\/h3>\n
Timeline<\/h3>\n
\n
<\/h3>\n
Credits<\/h3>\n