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[FireEye]XcodeGhost S: A New Breed Hits the US
« le: mai 15, 2019, 18:00:18 »
XcodeGhost S: A New Breed Hits the US

Just over a month ago, iOS users were warned of the threat to their
  devices by the XcodeGhost malware. Apple quickly reacted, taking down
  infected apps from the App Store and releasing new security features
  to stop malicious activities. Through continuous monitoring of our
  customers’ networks, FireEye researchers have found that, despite the
  quick response, the threat of XcodeGhost has maintained persistence
  and been modified.


 

More specifically, we found that:


 
  • XcodeGhost has entered into U.S. enterprises and is a
        persistent security risk
  • Its botnet is still partially
      active
  • A variant we call XcodeGhost S reveals more advanced
        samples went undetected

 

After monitoring XcodeGhost related activity for four weeks, we
  observed 210 enterprises with XcodeGhost-infected applications running
  inside their networks, generating more than 28,000 attempts to connect
  to the XcodeGhost Command and Control (CnC) servers -- which, while
  not under attacker control, are vulnerable to hijacking by threat
  actors. Figure 1 shows the top five countries XcodeGhost attempted to
  callback to during this time.


 


 


 


  Figure 1. Top five countries XcodeGhost
    attempted to callback in a four-week span


 

The 210 enterprises we detected with XcodeGhost infections represent
  a wide range of industries. Figure 2 shows the top five industries
  affected by XcodeGhost, sorted by the percentage of callback attempts
  to the XcodeGhost CnC servers from inside their networks:


 


 


 


  Figure 2: Top five industries affected based on
    callback attempts


 

Researchers have demonstrated how XcodeGhost CnC traffic can be
  hijacked to:


 
  • Distribute apps outside the App Store
  • Force browse to
      URL
  • Aggressively promote any app in the App Store by
        launching the download page directly
  • Pop-up phishing
      windows

 

Figure 3 shows the top 20 most active infected apps among 152 apps,
  based on data from our DTI cloud:


 


 


 


  Figure 3: Top 20 infected apps


 

Although most vendors have already updated their apps on App Store,
  this chart indicates many users are actively using older, infected
  versions of various apps in the field. The version distribution varies
  among apps. For example, the most popular Apps 网易云音乐 and
  WeChat-infected versions are listed in Figure 4.


 
   
     
   
              width="156" valign="bottom">

6.2.5.19

        width="156" valign="bottom">

2963


   
     
                width="156" valign="bottom">

3084


   
     
   
     


          App Name


          Version


          Incident Count (in 3 weeks)

WeChat

网易云音乐

Music 163

2.8.2

2.8.3

        valign="bottom">

2664

2.8.1

        valign="bottom">

1227


 


  Figure 4: Sample infected app versions


 

The infected iPhones are running iOS versions from 6.x.x to 9.x.x as
  illustrated by Figure 5. It is interesting to note that nearly 70% of
  the victims within our customer base remain on older iOS versions. We
  encourage them to update to the latest version iOS 9 as quickly as possible.


 


 


 


  Figure 5: Distribution of iOS versions running
    infected apps


 

Some enterprises have taken steps to block the XcodeGhost DNS query
  within their network to cut off the communication between employees’
  iPhones and the attackers’ CnC servers to protect them from being
  hijacked. However, until these employees update their devices and
  apps, they are still vulnerable to potential hijacking of the
  XcodeGhost CnC traffic -- particularly when outside their corporate networks.


 

Given the number of infected devices detected within a short period
  among so many U.S enterprises, we believe that XcodeGhost continues to
  be an ongoing threat for enterprises.


 


  XcodeGhost Modified to Exploit iOS 9


 

We have worked with Apple to have all XcodeGhost and XcodeGhost S
  (described below) samples we have detected removed from the App Store.


 

XcodeGhost is planted in different versions of Xcode, including
  Xcode 7 (released for iOS 9 development). In the latest version, which
  we call XcodeGhost S, features have been added to infect iOS 9 and
  bypass static detection.


 

According to [1], Apple introduced the “NSAppTransportSecurity”
  approach for iOS 9 to improve client-server connection security. By
  default, only secure connections (https with specific ciphers) are
  allowed on iOS 9. Due to this limitation, previous versions of
  XcodeGhost would fail to connect with the CnC server by using http.
  However, Apple also allows developers to add exceptions
  (“NSAllowsArbitraryLoads”) in the app’s Info.plist to allow http
  connection. As shown in Figure 6, the XcodeGhost S sample reads the
  setting of “NSAllowsArbitraryLoads” under the “NSAppTransportSecurity”
  entry in the app’s Info.plist and picks different CnC servers
  (http/https) based on this setting.


 


 


 


  Figure 6: iOS 9 adoption in XcodeGhost S


 

Further, the CnC domain strings are concatenated character by
  character to bypass the static detection in XcodeGhost S, such
  behavior is shown in Figure 7.


 


 


 


  Figure 7: Construct the CnC domain character by character


 

The FireEye iOS dynamic analysis platform has successfully detected
  an app  (“自由邦”)  [2] infected by XcodeGhost S and this app has been
  taken down from App Store in cooperation with Apple. It is a shopping
  app for travellers and is available on both U.S. and CN App Stores. As
  shown in Figure 8, the infected app’s version is 2.6.6, updated on
  Sep. 15.


 


 


 


  Figure 8: An App Store app is infected with
    XcodeGhost S


 


  Enterprise Protection


 


  FireEye MTP has
  detected and assisted in Apple’s takedown of thousands of
  XcodeGhost-infected iOS applications. We advise all organizations to
  notify their employees of the threat of XcodeGhost and other malicious
  iOS apps. Employees should make sure that they update all apps to the
  latest version. For the apps Apple has removed, users should remove
  the apps and switch to other uninfected apps on App Store.


 


  FireEye MTP management
  customers have full visibility into which mobile devices are infected
  in their deployment base. We recommend that customers immediately
  review MTP alerts, locate infected devices/users, and quarantine the
  devices until the infected apps are removed. FireEye NX customers are
  advised to immediately review alert logs for activities related to
  XcodeGhost communications.


 

[1]     href="https://developer.apple.com/library/prerelease/ios/technotes/App-Transport-Security-Technote/">h  href="https://developer.apple.com/library/prerelease/ios/technotes/App-Transport-Security-Technote/">ttps://developer.apple.com/library/prerelease/ios/technotes/App-Transport-Security-Technote/

  [2]   href="https://itunes.apple.com/us/app/id915233927">https://itunes.apple.com/us/app/id915233927

  [3]   href="http://drops.wooyun.org/papers/9024">http://drops.wooyun.org/papers/9024

  [4]   href="https://itunes.apple.com/us/app/pdf-reader-annotate-scan-sign/id368377690?mt=8">https://itunes.apple.com/us/app/pdf-reader-annotate-scan-sign/id368377690?mt=8

  [5]   href="https://itunes.apple.com/us/app/winzip-leading-zip-unzip-cloud/id500637987?mt=8">https://itunes.apple.com/us/app/winzip-leading-zip-unzip-cloud/id500637987?mt=8

  [7]   href="/content/fireeye-www/en_US/blog/threat-research/2015/08/ios_masque_attackwe.html">https://www.fireeye.com/blog/threat-research/2015/08/ios_masque_attackwe.html

  [8]   href="/content/fireeye-www/en_US/blog/threat-research/2015/02/ios_masque_attackre.html">https://www.fireeye.com/blog/threat-research/2015/02/ios_masque_attackre.html

  [9]   href="/content/fireeye-www/en_US/blog/threat-research/2014/11/masque-attack-all-your-ios-apps-belong-to-us.html">https://www.fireeye.com/blog/threat-research/2014/11/masque-attack-all-your-ios-apps-belong-to-us.html

  [10] https://www.fireeye.com/blog/threat-research/2015/06/three_new_masqueatt.html


Source: XcodeGhost S: A New Breed Hits the US

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[FireEye]XcodeGhost S: A New Breed Hits the US
« le: mai 15, 2019, 18:00:18 »

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