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arXiv 2203.09374cs.CR
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Android非SDK(隐藏)服务API安全性的系统研究

A Systematic Study of Android Non-SDK (Hidden) Service API Security

Yi He, Yacong Gu, Purui Su, Kun Sun, Yajin Zhou, Zhi Wang, Qi Li

摘要:

Android允许应用通过系统服务助手与其系统服务通信,以便这些应用可以使用系统服务提供的各种功能。同时,系统服务依赖于其服务助手来执行安全检查以提供保护。不幸的是,服务助手中的安全检查可能会通过直接利用非SDK(隐藏)API而被绕过,从而降低稳定性并造成严重的安全威胁,例如权限提升,自动执行功能而无需用户交互,崩溃和DoS攻击。Google已经提出了各种方法来解决这个问题,例如,逐个修复bug,甚至提出黑名单来阻止所有非SDK API。然而,开发人员仍然可以找到利用这些隐藏的API来规避非SDK限制的新方法。在本文中,我们系统地研究了由于隐藏的API利用漏洞,并分析了谷歌的对策的有效性。我们的目标是回答在最新的Android 12中是否仍然存在可被利用的易受攻击的隐藏API。我们开发了一个名为ServiceAudit的静态分析工具来自动挖掘服务助手类和隐藏的服务API之间不一致的安全执行。我们将ServiceAudit应用于Android 6~12。我们的工具发现了Android 6中的112个漏洞,其精度高于现有方法。此外,在Android 11和12中,我们发现了超过25个具有不一致保护的隐藏API;然而,在Android 11中,只有一个易受攻击的API会导致严重的安全问题,并且它们都不能在Android 12上工作。

英文摘要:

Android allows apps to communicate with its system services via system service helpers so that these apps can use various functions provided by the system services. Meanwhile, the system services rely on their service helpers to enforce security checks for protection. Unfortunately, the security checks in the service helpers may be bypassed via directly exploiting the non-SDK (hidden) APIs, degrading the stability and posing severe security threats such as privilege escalation, automatic function execution without users' interactions, crashes, and DoS attacks. Google has proposed various approaches to address this problem, e.g., case-by-case fixing the bugs or even proposing a blacklist to block all the non-SDK APIs. However, the developers can still figure out new ways of exploiting these hidden APIs to evade the non-SDKs restrictions. In this paper, we systematically study the vulnerabilities due to the hidden API exploitation and analyze the effectiveness of Google's countermeasures. We aim to answer if there are still vulnerable hidden APIs that can be exploited in the newest Android 12. We develop a static analysis tool called ServiceAudit to automatically mine the inconsistent security enforcement between service helper classes and the hidden service APIs. We apply ServiceAudit to Android 6~12. Our tool discovers 112 vulnerabilities in Android 6 with higher precision than existing approaches. Moreover, in Android 11 and 12, we identify more than 25 hidden APIs with inconsistent protections; however, only one of the vulnerable APIs can lead to severe security problems in Android 11, and none of them work on Android 12.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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