{"id":5040,"date":"2015-03-10T14:08:36","date_gmt":"2015-03-10T19:08:36","guid":{"rendered":"http:\/\/www.zdziarski.com\/blog\/?p=5040"},"modified":"2015-03-10T14:24:56","modified_gmt":"2015-03-10T19:24:56","slug":"testing-for-a-compromised-xcode","status":"publish","type":"post","link":"https:\/\/www.zdziarski.com\/blog\/?p=5040","title":{"rendered":"Testing for the Strawhorse Backdoor in Xcode"},"content":{"rendered":"

In the previous blog post<\/a>, I highlighted the latest Snowden documents, which reveal a CIA project out of Sandia National Laboratories to author a malicious version of Xcode. This Xcode malware targeted App Store developers by installing a backdoor on their computers to steal their private codesign keys.<\/p>\n

\"Screen<\/a><\/p>\n

So how do you test for a backdoor you’ve never seen before? By verifying that the security mechanisms it disables are working correctly. Based on the document, the malware apparently infects Apple’s\u00a0securityd<\/em>\u00a0daemon to prevent it from warning the user prior to exporting developer keys:<\/p>\n

“… which rewrites securityd so that no prompt appears when exporting a developer’s private key”<\/em><\/p>\n

A good litmus test to see if\u00a0securityd<\/em>\u00a0has been compromised in this way is to attempt to export your own developer keys and see if you are prompted for permission.<\/p>\n

<\/p>\n

Following these instructions<\/a> from Apple, you can export your signing identity.<\/p>\n

    \n
  1. In the Xcode Preferences window, click Accounts<\/li>\n
  2. Click the Action button (to the right of the minus button) in the lower-left corner.<\/li>\n
  3. Select Export Accounts from the pop-up menu.<\/li>\n<\/ol>\n

    When you export your accounts,\u00a0securityd<\/em> should pop up a window asking for permission to allow this action.<\/p>\n

    \"Screen<\/a><\/p>\n

    If you don’t see this popup, something’s wrong, and it’s possible that your system may have been compromised to prevent the user from knowing their keys were being exported.<\/p>\n

    Since we have no samples of the malware allegedly developed for CIA, there’s no way to guarantee that this is a sure-fire way to detect compromise. Based on the slides, however, this warning should be removed on compromised systems, at least under certain circumstances.<\/p>\n","protected":false},"excerpt":{"rendered":"

    In the previous blog post<\/a>, I highlighted the latest Snowden documents, which reveal a CIA project out of Sandia National Laboratories to author a malicious version of Xcode. This Xcode malware targeted App Store developers by installing a backdoor on their computers to steal their private codesign keys.<\/p>\n

    \"Screen<\/a><\/p>\n

    So how do you test for a backdoor you’ve never seen before? By verifying that the security mechanisms it disables are working correctly. Based on the document, the malware apparently infects Apple’s\u00a0securityd<\/em>\u00a0daemon to prevent it from warning the user prior to exporting developer keys:<\/p>\n

    “… which rewrites securityd so that no prompt appears when exporting a developer’s private key”<\/em><\/p>\n

    A good litmus test to see if\u00a0securityd<\/em>\u00a0has been compromised in this way is to attempt to export your own developer keys and see if you are prompted for permission.<\/p>\n

    Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11,14],"tags":[],"class_list":["post-5040","post","type-post","status-publish","format-standard","hentry","category-apple","category-security"],"_links":{"self":[{"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5040","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5040"}],"version-history":[{"count":0,"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/5040\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5040"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5040"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zdziarski.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5040"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}