| page.title= Security updates and resources |
| @jd:body |
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| <div id="qv-wrapper"> |
| <div id="qv"> |
| <h2>In this document</h2> |
| <ol id="auto-toc"></ol> |
| </div> |
| </div> |
| |
| <h2 id=android_security_bug_lifecycle>Android security bug lifecycle</h2> |
| |
| <p>The Android security team is responsible for managing security vulnerabilities |
| discovered in the Android platform and many of the core Android apps bundled |
| with Android devices.</p> |
| |
| <p>The Android security team finds security vulnerabilities through internal |
| research and also responds to bugs reported by third parties. Sources of |
| external bugs include issues reported through the <a |
| href="https://code.google.com/p/android/issues/list">Android Open Source |
| Project (AOSP) bug tracker</a>, published and pre-published academic research, |
| upstream open source project maintainers, notifications from our device |
| manufacturer partners, and publicly disclosed issues posted on blogs or social |
| media.</p> |
| |
| <h2 id=report-issues>Reporting security issues</h2> |
| |
| <p>Any developer, Android user, or security researcher can notify the Android |
| security team of potential security issues through the AOSP bug tracker <a |
| href="https://code.google.com/p/android/issues/entry?template=Security%20bug%20report">Security |
| bug report</a> template.</p> |
| |
| <p>Bugs marked as security issues are not externally visible, but they may |
| eventually be made visible after the issue is evaluated or resolved. If you |
| plan to submit a patch or Compatibility Test Suite (CTS) test to resolve a |
| security issue, please attach it to the bug report and wait for a response |
| before uploading the code to AOSP.</p> |
| |
| <p>If you need to reach the Android security team for a purpose other than |
| reporting a vulnerability, please contact <a |
| href="mailto:security@android.com">security@android.com</a>. The Android |
| security team has a <a |
| href="https://developer.android.com/security_at_android_dot_com.txt">PGP |
| key</a> if you need to encrypt your message.</p> |
| |
| <h2 id=triaging_bugs>Triaging bugs</h2> |
| |
| <p>The first task in handling a security vulnerability is to identify the severity |
| of the bug and which component of Android is affected. The severity determines |
| how the issue is prioritized, and the component determines who fixes the bug, |
| who is notified, and how the fix gets deployed to users.</p> |
| |
| <h3 id=severity>Severity</h3> |
| |
| <p>The severity of a bug generally reflects the potential harm that could occur if |
| a bug was successfully exploited. Use the following criteria to determine the |
| severity:</p> |
| <p class="table-caption" id="severity-criteria"> |
| <strong>Table 1.</strong> Severity ratings and associated consequences</p> |
| <table> |
| <tr> |
| <th>Rating</th> |
| <th>Consequence of successful exploitation</th> |
| </tr> |
| <tr> |
| <td><strong>Critical</strong></td> |
| <td> |
| <ul> |
| <li>Remote privileged code execution (execution at a privilege level that |
| third-party apps cannot obtain) |
| <li>Local permanent device compromise (device cannot be repaired without |
| re-flashing the entire operating system, such as a verified boot or Trusted |
| Execution Environment/TEE compromise) |
| <li>Remote permanent denial of service (inoperability, either completely permanent |
| or requiring re-flashing the device) |
| </ul> |
| </td> |
| </tr> |
| <tr> |
| <td><strong>High</strong></td> |
| <td> |
| <ul> |
| <li>Remote unprivileged code execution (execution at a privilege level that |
| third-party apps can obtain through installation) |
| <li>Local access to system/signature-level permission data or capabilities without |
| permission |
| <li>Local permanent denial-of-service (inoperability, either completely permanent |
| or requiring re-flashing the device) |
| <li>Remote temporary denial-of-service (remote hang or reboot) |
| </ul> |
| </td> |
| </tr> |
| <tr> |
| <td><strong>Moderate</strong></td> |
| <td> |
| <ul> |
| <li>Access to "<a |
| href="http://developer.android.com/guide/topics/manifest/permission-element.html#plevel">dangerous</a>" |
| level permission data or capabilities without permission with an app installed |
| on the device |
| <li>Local temporary denial-of-service (can be resolved only through a factory |
| reset) |
| </ul> |
| </td> |
| </tr> |
| <tr> |
| <td><strong>Low</strong></td> |
| <td> |
| <ul> |
| <li>Access to "<a |
| href="http://developer.android.com/guide/topics/manifest/permission-element.html#plevel">normal</a>" |
| level permission capabilities without permission with an app installed on the |
| device |
| <li>Local temporary denial-of-service (can be resolved by booting the device into |
| Safe Mode and removing the problem application) |
| </ul> |
| </td> |
| </tr> |
| </table> |
| |
| <p>Though there are many types of software bugs outside of the security |
| vulnerabilities detailed above, bugs reported are evaluated on a |
| case-by-base basis to determine what security impact they have.</p> |
| |
| <p>The Android security team may also adjust the severity of a vulnerability if it |
| is determined the risk to users is higher or lower than the guidelines suggest. |
| For example, if a certain piece of data is available only to apps with "system" |
| level access but the data itself is not sensitive, the Android security |
| team may consider it only a low-severity vulnerability.</p> |
| |
| <h4 id=local_vs_remote>Local vs. remote</h4> |
| |
| <p>A remote attack vector indicates the bug could be exploited without installing |
| an app or without physical access to the device. This includes bugs that could |
| be triggered by browsing to a web page, reading an email, receiving an SMS |
| message, or connecting to a hostile network. For the purpose of our severity |
| ratings, the Android security team also considers "proximal" attack vectors as |
| remote. These include bugs that can be exploited only by an attacker who is |
| physically near the target device, for example a bug that requires sending |
| malformed Wi-Fi or Bluetooth packets.</p> |
| |
| <p>Local attacks require the victim to install an app. For the purpose of severity |
| ratings, the Android security team also considers physical attack vectors as |
| local. These include bugs that can be exploited only by an attacker who has |
| physical access to the device, for example a bug in a lock screen or one that |
| requires plugging in a USB cable. The Android security team also considers |
| NFC-based attacks as local.</p> |
| |
| <h4 id=high_privilege_levels>Severity of vulnerabilities that affect high privilege levels</h4> |
| |
| <p>The Android security team will usually drop the severity rating for a bug that |
| already requires executing code at a high privilege level. For example, a bug |
| in a kernel driver accessible only from a privileged service that |
| requires first compromising the service. In this case, the Android security |
| team may drop the severity from "high" to "moderate."</p> |
| |
| <h4 id=severity_of_kernel_compromises>Severity of kernel compromises</h4> |
| |
| <p>Whether a vulnerability that compromises the kernel is considered "high" or |
| "critical" depends on the device and the version of Android. On devices with a |
| TEE (or TrustZone) and <a |
| href="http://source.android.com/devices/tech/security/verifiedboot/index.html">verified |
| boot</a>, a kernel compromise is considered "high" because exploiting it won't |
| allow permanently affecting the operation of the device unless a vulnerability is |
| discovered in the TEE or verified boot implementation. In general, if the |
| result of a compromise can be remediated with a factory reset, it's "high" or |
| lower.</p> |
| |
| <p>However, on older devices without verified boot, a kernel compromise can result |
| in permanent device compromise if SELinux is disabled and the system partition |
| is modified. On that device, a kernel compromise is considered "critical" |
| because remediation requires re-flashing the device's firmware image.</p> |
| |
| <h3 id=affected_component>Affected component</h3> |
| |
| <p>The development team responsible for fixing the bug depends on which component |
| the bug is in. It could be a core component of the Android platform, a kernel |
| driver supplied by an original equipment manufacturer (OEM), or one of the |
| pre-loaded apps on Nexus devices.</p> |
| |
| <p>Bugs in AOSP code are fixed by the Android engineering team. Low-severity bugs, |
| bugs in certain components, or bugs that are already publicly known may be |
| fixed directly in the publicly available AOSP master branch; otherwise they're |
| fixed in our internal repositories first.</p> |
| |
| <p>The component is also a factor in how users get updates. A bug in the framework |
| or kernel will require an over-the-air (OTA) firmware update that each OEM will |
| need to push. A bug in an app or library published in Google Play (e.g., Gmail, |
| Google Play Services, WebView in Lollipop and later versions) can be sent to |
| Android users as an update from Google Play. </p> |
| |
| <h2 id=notifying_partners>Notifying partners</h2> |
| |
| <p>When a moderate or higher severity security vulnerability in AOSP is fixed, |
| we'll notify <a href="http://www.openhandsetalliance.com/">Open Handset |
| Alliance</a> members with the details of the issue and provide patches for the |
| most recent three Android releases. The Android security team currently |
| provides patches for Android versions 4.4 (KitKat), 5.0 (Lollipop), and 5.1 |
| (Lollipop MR1). This list of backport-supported versions changes with each new |
| Android release.</p> |
| |
| <h2 id=releasing_code_to_aosp>Releasing code to AOSP</h2> |
| |
| <p>If the security bug is in an AOSP component, the fix will be pushed out to AOSP |
| after the OTA is released to users. Fixes for low-severity issues may be |
| submitted directly to the AOSP master branch before a fix is available.</p> |
| |
| <h2 id=android_updates>Receiving Android updates</h2> |
| |
| <p>Updates to the Android system are generally delivered to devices through |
| OTA update packages. These updates may come from the OEM who |
| produced the device or the carrier who provides service to the device. Google |
| Nexus device updates come from the Google Nexus team after going through a |
| carrier technical acceptance (TA) testing procedure. Google also publishes <a |
| href="https://developers.google.com/android/nexus/images">Nexus factory |
| images</a> that can be side-loaded to devices.</p> |
| |
| <h2 id=updating_google_services>Updating Google services</h2> |
| |
| <p>In addition to providing patches for security bugs, the Android security team |
| also review security bugs to determine if there are other ways to protect |
| users. For example, Google Play scans all applications and will remove any |
| application that attempts to exploit a security bug. For applications installed |
| from outside of Google Play, devices with Google Play Services may also use the |
| <a href="https://support.google.com/accounts/answer/2812853">Verify Apps</a> |
| feature to warn users about applications that may be potentially harmful.</p> |
| |
| <h2 id=other_resources>Other resources</h2> |
| |
| <p>Information for Android application developers: <a |
| href="https://developer.android.com">https://developer.android.com</a></p> |
| |
| <p>The Android security team can be reached at <a |
| href="mailto:security@android.com">security@android.com</a>. Our PGP key: <a |
| href="https://developer.android.com/security_at_android_dot_com.txt">https://developer.android.com/security_at_android_dot_com.txt</a></p> |
| |
| <p>Security information exists throughout the Android Open Source and Developer |
| sites. Good places to start:<br> |
| <a href="http://source.android.com/devices/tech/security/index.html">http://source.android.com/devices/tech/security/index.html</a><br> |
| <a href="https://developer.android.com/guide/topics/security/security.html">https://developer.android.com/guide/topics/security/security.html</a></p> |
| |
| <p>Security best practices for developers: <a |
| href="https://developer.android.com/guide/practices/security.html">https://developer.android.com/guide/practices/security.html</a>.</p> |
| |
| <p>Community resource for discussion about Android security: <a |
| href="https://groups.google.com/forum/?fromgroups#!forum/android-security-discuss">https://groups.google.com/forum/?fromgroups#!forum/android-security-discuss</a></p> |