XPOSED魔改一：获取特征
写在前面
受这篇文章——《定制Xposed框架》启发，决定自己也尝试一下。
尝试的过程中发现，文章写得太“简约”了，基本上毫无细节，后人想下手或复现非常困难，对Xposed各模块之间的关系也没有介绍，有点“干”，不易于理解，于是有了此文。
本文细节非常多，相当于手把手，篇幅过长所以分拆成三篇：
XPOSED魔改一：获取特征XPOSED魔改二：编译源码XPOSED魔改三：更改特征
部分附件（镜像、刷机文件等）位于我的github：https://github.com/r0ysue/AndroidSecurityStudy的FART/picC文件夹中。
话不多说，进入正题，既然想要抹掉XPOSED框架的特征，那么首先得知道XPOSED框架有哪些特征，才能有的放矢、对症下药。
准备环境：选择XPOSED版本v89
从Xposed官方发布频道得知，sdk27版本（也就是安卓8.1）的Xposed还是beta的状态：
最新的正式版是sdk25（也就是安卓7.1），已经是2017年的了：
当然最重要的还是Github主页上开源的版本只到v89，也就是安卓7.1；而不是安卓8的v90系列。
准备环境：选择谷歌原版镜像7.1.2
Xposed今后应该也不会更新了，我们以android-7.1.2_r8版本来进行编译。
首先只需要收集特征，我们先下载其线程的谷歌镜像进行刷机即可：
在Link上右键复制链接地址，可以直接黏贴到国内环境的浏览器里下载的，也可以直接wget：
# wget https://dl.google.com/dl/android/aosp/sailfish-n2g47o-factory-f2bc8024.zip
--2020-03-29 10:18:25-- https://dl.google.com/dl/android/aosp/sailfish-n2g47o-factory-f2bc8024.zip
Resolving dl.google.com (dl.google.com)... 203.208.43.101, 203.208.43.102, 203.208.43.104, ...
Connecting to dl.google.com (dl.google.com)|203.208.43.101|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1914505658 (1.8G) [application/zip]
Saving to: ‘sailfish-n2g47o-factory-f2bc8024.zip’
sailfish-n2g47o-factory-f2bc 100%[============================================>] 1.78G 10.5MB/s in 3m 25s
2020-03-29 10:21:51 (8.92 MB/s) - ‘sailfish-n2g47o-factory-f2bc8024.zip’ saved [1914505658/1914505658]
下载完成后进行解压：
# unzip sailfish-n2g47o-factory-f2bc8024.zip
Archive: sailfish-n2g47o-factory-f2bc8024.zip
creating: sailfish-n2g47o/
inflating: sailfish-n2g47o/radio-sailfish-8996-012901-1702171013.img
inflating: sailfish-n2g47o/bootloader-sailfish-8996-012001-1703151359.img
inflating: sailfish-n2g47o/flash-all.bat
inflating: sailfish-n2g47o/flash-all.sh
extracting: sailfish-n2g47o/image-sailfish-n2g47o.zip
inflating: sailfish-n2g47o/flash-base.sh
如果电脑里没有安装fastboot，可以先下载一下：
# wget wget https://dl.google.com/android/repository/platform-tools-latest-linux.zip
--2020-03-29 10:24:28-- http://wget/
Resolving wget (wget)... failed: Name or service not known.
wget: unable to resolve host address ‘wget’
--2020-03-29 10:24:29-- https://dl.google.com/android/repository/platform-tools-latest-linux.zip
Resolving dl.google.com (dl.google.com)... 203.208.50.167, 203.208.50.164, 203.208.50.174, ...
Connecting to dl.google.com (dl.google.com)|203.208.50.167|:443... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://dl.google.com/android/repository/platform-tools_r29.0.6-linux.zip [following]
--2020-03-29 10:24:29-- https://dl.google.com/android/repository/platform-tools_r29.0.6-linux.zip
Reusing existing connection to dl.google.com:443.
HTTP request sent, awaiting response... 200 OK
Length: 8254604 (7.9M) [application/zip]
Saving to: ‘platform-tools-latest-linux.zip.1’
platform-tools-latest-linux. 100%[============================================>] 7.87M 9.76MB/s in 0.8s
2020-03-29 10:24:30 (9.76 MB/s) - ‘platform-tools-latest-linux.zip.1’ saved [8254604/8254604]
FINISHED --2020-03-29 10:24:30--
Total wall clock time: 2.3s
Downloaded: 1 files, 7.9M in 0.8s (9.76 MB/s)
解压并将fastboot命令加入当前终端的路径中去：
# unzip platform-tools-latest-linux.zip
inflating: platform-tools/systrace/catapult/systrace/systrace/__init__.py
inflating: platform-tools/systrace/catapult/systrace/systrace/monitor_unittest.py
inflating: platform-tools/systrace/catapult/systrace/systrace/LICENSE
inflating: platform-tools/systrace/catapult/systrace/systrace/tracing_controller.py
inflating: platform-tools/systrace/catapult/systrace/systrace/update_systrace_trace_viewer.py
inflating: platform-tools/systrace/catapult/systrace/systrace/prefix.html
creating: platform-tools/systrace/catapult/systrace/systrace/tracing_agents/
inflating: platform-tools/systrace/catapult/systrace/systrace/tracing_agents/walt_agent_unittest.py
inflating: platform-tools/systrace/catapult/systrace/systrace/tracing_agents/__init__.py
...
...
# pwd （获取当前路径）
# export PATH=$PATH:/当前路径/platform-tools/
测试一下当前终端中有fastboot命令了么？如果有，会打印出一堆帮助信息。
# fastboot -h
usage: fastboot [OPTION...] COMMAND...
flashing:
update ZIP Flash all partitions from an update.zip package.
flashall Flash all partitions from $ANDROID_PRODUCT_OUT.
On A/B devices, flashed slot is set as active.
Secondary images may be flashed to inactive slot.
flash PARTITION [FILENAME] Flash given partition, using the image from
$ANDROID_PRODUCT_OUT if no filename is given.
basics:
devices [-l] List devices in bootloader (-l: with device paths).
getvar NAME Display given bootloader variable.
reboot [bootloader] Reboot device.
locking/unlocking:
flashing lock|unlock Lock/unlock partitions for flashing
flashing lock_critical|unlock_critical
Lock/unlock 'critical' bootloader partitions.
flashing get_unlock_ability
Check whether unlocking is allowed (1) or not(0).
将手机进入bootloader模式，这里以pixel一代sailfish为例，刚刚下载的镜像也是专为sailfish这个型号准备的。首先完全关闭手机（可以等关机息屏后再等待一分钟），然后按住音量向下键，再按开机键开机，手机会进入如图状态，就是bootloader模式：
usb线连接到电脑后，可以使用fastboot命令检测到：
如果系统是在VMware里，那么要确保usb口连接到VMware里的Linux系统。
# fastboot devices
FA69P0300560 fastboot
最终就是进入刚刚解压出来的sailfish镜像文件夹，运行其中的flash-all.sh命令即可。
# cd sailfish-n2g47o/
# ./flash-all.sh
Sending 'bootloader_b' (32380 KB) OKAY [ 3.792s]
Writing 'bootloader_b' (bootloader) Valid bootloader version.
(bootloader) Flashing active slot "_b"
(bootloader) Flashing active slot "_b"
OKAY [ 12.260s]
Finished. Total time: 16.250s
Rebooting into bootloader OKAY [ 0.048s]
Finished. Total time: 0.149s
< waiting for any device >
Sending 'radio_b' (57240 KB) OKAY [ 6.854s]
Writing 'radio_b' OKAY [ 0.951s]
Finished. Total time: 7.991s
Rebooting into bootloader OKAY [ 0.045s]
Finished. Total time: 0.096s
--------------------------------------------
Bootloader Version...: 8996-012001-1703151359
Baseband Version.....: 8996-012901-1702171013
Serial Number........: FA69P0306926
--------------------------------------------
extracting android-info.txt (0 MB) to RAM...
Checking 'product' OKAY [ 0.048s]
Checking 'version-bootloader' OKAY [ 0.050s]
Checking 'version-baseband' OKAY [ 0.050s]
Setting current slot to 'b' OKAY [ 0.405s]
extracting boot.img (24 MB) to disk... took 0.353s
archive does not contain 'boot.sig'
Sending 'boot_b' (24653 KB) OKAY [ 3.192s]
Writing 'boot_b' OKAY [ 0.605s]
archive does not contain 'system.sig'
Sending sparse 'system_b' 1/4 (521196 KB) OKAY [ 64.041s]
Writing 'system_b' OKAY [ 7.893s]
Sending sparse 'system_b' 2/4 (524080 KB) OKAY [ 66.481s]
Writing 'system_b' OKAY [ 15.006s]
Sending sparse 'system_b' 3/4 (496387 KB) OKAY [ 60.688s]
Writing 'system_b' OKAY [ 7.644s]
Sending sparse 'system_b' 4/4 (32756 KB) OKAY [ 4.007s]
Writing 'system_b' OKAY [ 0.996s]
archive does not contain 'system_ext.img'
extracting system_other.img (1641 MB) to disk... took 30.917s
archive does not contain 'system.sig'
Sending sparse 'system_a' 1/4 (520579 KB) OKAY [ 64.744s]
Writing 'system_a' OKAY [ 5.791s]
Sending sparse 'system_a' 2/4 (521193 KB) OKAY [ 63.390s]
Writing 'system_a' OKAY [ 6.042s]
Sending sparse 'system_a' 3/4 (510220 KB) OKAY [ 61.388s]
Writing 'system_a' OKAY [ 5.191s]
Sending sparse 'system_a' 4/4 (128745 KB) OKAY [ 15.756s]
Writing 'system_a' OKAY [ 1.953s]
extracting vendor.img (236 MB) to disk... took 4.279s
archive does not contain 'vendor.sig'
Sending 'vendor_b' (242102 KB) OKAY [ 29.721s]
Writing 'vendor_b' OKAY [ 7.801s]
archive does not contain 'vendor_other.img'
Erasing 'userdata' OKAY [ 6.061s]
mke2fs 1.45.4 (23-Sep-2019)
Creating filesystem with 6509568 4k blocks and 1630208 inodes
Filesystem UUID: 4b251af0-28e0-479e-b726-813ed8a0ed0c
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
Sending 'userdata' (4272 KB) OKAY [ 0.572s]
Writing 'userdata' OKAY [ 0.111s]
Rebooting OKAY [ 0.050s]
Finished. Total time: 567.899s
安装成功就会出现finished字样，并且手机重启，进入系统。
准备环境：使用SuperSU进行root
貌似Magisk环境与XPOSED是有冲突的，不然不会有[Magisk] Systemless Xposed v89.3/v90.2-beta3 (SDK 21-27)这种产物了，所以幸亏我们选择的是7.1.2，用老牌的SuperSU还是支持的。
SuperSU官网提供的下载已经无法下载了，所以在其他网盘里找到个能用的SR3-SuperSU-v2.82-SR3-20170813133244.zip，用TWRP刷进这个SuperSU就行了。
TWRP则使用这个版本：twrp-3.2.1-0-sailfish.img，先都下载了。
- 首先手机进入
bootloader状态，这个上文已经讲过；
- 使用
fastboot命令加载TWRP，
# fastboot boot twrp-3.2.1-0-sailfish.img
Sending 'boot.img' (30948 KB) OKAY [ 3.981s]
Booting OKAY [ 1.005s]
Finished. Total time: 5.160s
- 待
TWRP完全开机之后，将SR3-SuperSU-v2.82-SR3-20170813133244.zip推送到/sdcard/目录下：
# adb push SR3-SuperSU-v2.82-SR3-20170813133244.zip /sdcard/
* daemon not running; starting now at tcp:5037
* daemon started successfully
SR3-SuperSU-v2.82-SR3-20170813133244.zip: 1 file pushed, 0 skipped. 21.8 MB/s (6918737 bytes in 0.303s)
- 选择
Install，浏览到/sdcard/目录下，点选SR3-SuperSU-v2.82-SR3-20170813133244.zip文件，将最下方滑块从最左拖到最右，即开始刷入SuperSU。刷入成功后如图所示。
选择Reboot System→ Do Not Install即可。
准备环境：安装Xposed框架并激活插件
下载安装最新版xposed.installer_3.1.5，下载完安装和打开，然后安装Xposed的底包，具体流程见下图。
安装、重启完成后，须出现“Xposed框架89版已激活”字样，绿色勾勾（而不是红色或黄色）。在Xposed Installer的“下载”模块里找到GraviryBox[N]安装和激活，然后让状态栏文字变成如图绿色康康（原来为白色）。
到这里框架和插件都安装成功并正常使用了。
收集特征：底包详细信息
从手机里把底包抽出来，也就是xposed-v89-sdk25-arm64.zip，应该就是服务器上的https://dl-xda.xposed.info/framework/sdk25/arm64/xposed-v89-sdk25-arm64.zip，解压康康发现里面东西很多。
这个里面最关键的就是安装包文件做了什么，这里只取最关键的康康，其余拷贝证书之类的，心里有数就好：
# cat META-INF/com/google/android/flash-script.sh
##########################################################################################
#
# Xposed framework installer zip.
#
# This script installs the Xposed framework files to the system partition. 该脚本将Xposed框架安装到系统分区
# The Xposed Installer app is needed as well to manage the installed modules. XposedInstaller用来管理模块
#
##########################################################################################
...
...
##########################################################################################
echo "******************************"
echo "Xposed framework installer zip" 框架安装
echo "******************************"
if [ ! -f "system/xposed.prop" ]; then
echo "! Failed: Extracted file system/xposed.prop not found!"
exit 1
fi
# 挂载system和vendor分区可读可写
echo "- Mounting /system and /vendor read-write"
mount /system >/dev/null 2>&1
mount /vendor >/dev/null 2>&1
mount -o remount,rw /system
mount -o remount,rw /vendor >/dev/null 2>&1
if [ ! -f '/system/build.prop' ]; then
echo "! Failed: /system could not be mounted!"
exit 1
fi
# 检查环境并设置变量
echo "- Checking environment"
API=$(grep_prop ro.build.version.sdk)
APINAME=$(android_version $API)
ABI=$(grep_prop ro.product.cpu.abi | cut -c-3)
ABI2=$(grep_prop ro.product.cpu.abi2 | cut -c-3)
ABILONG=$(grep_prop ro.product.cpu.abi)
XVERSION=$(grep_prop version system/xposed.prop)
XARCH=$(grep_prop arch system/xposed.prop)
XMINSDK=$(grep_prop minsdk system/xposed.prop)
XMAXSDK=$(grep_prop maxsdk system/xposed.prop)
XEXPECTEDSDK=$(android_version $XMINSDK)
if [ "$XMINSDK" != "$XMAXSDK" ]; then
XEXPECTEDSDK=$XEXPECTEDSDK' - '$(android_version $XMAXSDK)
fi
ARCH=arm
IS64BIT=
if [ "$ABI" = "x86" ]; then ARCH=x86; fi;
if [ "$ABI2" = "x86" ]; then ARCH=x86; fi;
if [ "$API" -ge "21" ]; then
if [ "$ABILONG" = "arm64-v8a" ]; then ARCH=arm64; IS64BIT=1; fi;
if [ "$ABILONG" = "x86_64" ]; then ARCH=x64; IS64BIT=1; fi;
fi
# 这一行其实输出更加详细的信息，只是被作者注销掉了
# echo "DBG [$API] [$ABI] [$ABI2] [$ABILONG] [$ARCH] [$XARCH] [$XMINSDK] [$XMAXSDK] [$XVERSION]"
# 只输出了简化版信息，图片中有。
echo " Xposed version: $XVERSION"
# 如果各种信息不匹配，则输出错误信息
XVALID=
if [ "$ARCH" = "$XARCH" ]; then
if [ "$API" -ge "$XMINSDK" ]; then
if [ "$API" -le "$XMAXSDK" ]; then
XVALID=1
else
echo "! Wrong Android version: $APINAME"
echo "! This file is for: $XEXPECTEDSDK"
fi
else
echo "! Wrong Android version: $APINAME"
echo "! This file is for: $XEXPECTEDSDK"
fi
else
echo "! Wrong platform: $ARCH"
echo "! This file is for: $XARCH"
fi
if [ -z $XVALID ]; then
echo "! Please download the correct package"
echo "! for your platform/ROM!"
exit 1
fi
# 上面环境监测都通过时，就开始把不同的文件放到相应的位置上去，区分32位和64位。
echo "- Placing files"
install_nobackup /system/xposed.prop 0 0 0644
install_nobackup /system/framework/XposedBridge.jar 0 0 0644
install_and_link /system/bin/app_process32 0 2000 0755 u:object_r:zygote_exec:s0
install_overwrite /system/bin/dex2oat 0 2000 0755 u:object_r:dex2oat_exec:s0
install_overwrite /system/bin/oatdump 0 2000 0755
install_overwrite /system/bin/patchoat 0 2000 0755 u:object_r:dex2oat_exec:s0
install_overwrite /system/lib/libart.so 0 0 0644
install_overwrite /system/lib/libart-compiler.so 0 0 0644
install_overwrite /system/lib/libart-disassembler.so 0 0 0644
install_overwrite /system/lib/libsigchain.so 0 0 0644
install_nobackup /system/lib/libxposed_art.so 0 0 0644
if [ $IS64BIT ]; then
install_and_link /system/bin/app_process64 0 2000 0755 u:object_r:zygote_exec:s0
install_overwrite /system/lib64/libart.so 0 0 0644
install_overwrite /system/lib64/libart-compiler.so 0 0 0644
install_overwrite /system/lib64/libart-disassembler.so 0 0 0644
install_overwrite /system/lib64/libsigchain.so 0 0 0644
install_nobackup /system/lib64/libxposed_art.so 0 0 0644
fi
if [ "$API" -ge "22" ]; then
find /system /vendor -type f -name '*.odex.gz' 2>/dev/null | while read f; do mv "$f" "$f.xposed"; done
fi
echo "- Done"
exit 0
也就是说该脚本的实质，把确保安装包没有下错，跟系统环境是匹配的，以及把不同的文件放到相应的位置上去。这里我们有了基本的概念，至少我们最终编译出来的可以刷机的包，得包含下列文件，他们最终会被放在系统的system/bin/、system/framework/、system/lib64/位置上。
简单地搜下字符串，可以看到几乎所有的二进制文件中都含有xposed的字符串，我们最终的目标最起码要拿掉xposed的字符串特征。
# grep -ril "xposed" *
META-INF/CERT.SF
META-INF/MANIFEST.MF
META-INF/com/google/android/update-binary
META-INF/com/google/android/flash-script.sh
system/lib64/libxposed_art.so
system/lib64/libart-compiler.so
system/lib64/libart.so
system/lib/libxposed_art.so
system/lib/libart-compiler.so
system/lib/libart.so
system/bin/oatdump
system/bin/dex2oat
system/bin/app_process32_xposed
system/bin/app_process64_xposed
xposed-v89-sdk25-arm64.zip
这些文件的用途及与源码的比对我们下一章再详细介绍。
收集特征：日志输出信息
Xposed插件在运行的时候会输出日志，如下图：
可以提取出来看个完整的：
# cat xposed_error_20200331_150832.log
03-31 14:06:50.383 I/Xposed ( 713): -----------------
03-31 14:06:50.383 I/Xposed ( 713): Starting Xposed version 89, compiled for SDK 25
03-31 14:06:50.384 I/Xposed ( 713): Device: Pixel (Google), Android version 7.1.2 (SDK 25)
03-31 14:06:50.384 I/Xposed ( 713): ROM: N2G47O
03-31 14:06:50.384 I/Xposed ( 713): Build fingerprint: google/sailfish/sailfish:7.1.2/N2G47O/3852959:user/release-keys
03-31 14:06:50.384 I/Xposed ( 713): Platform: arm64-v8a, 64-bit binary, system server: yes
03-31 14:06:50.384 I/Xposed ( 713): SELinux enabled: yes, enforcing: yes
03-31 14:06:51.426 I/Xposed ( 713): -----------------
03-31 14:06:51.426 I/Xposed ( 713): Added Xposed (/system/framework/XposedBridge.jar) to CLASSPATH
03-31 14:06:52.425 I/Xposed ( 713): Detected ART runtime
03-31 14:06:52.433 I/Xposed ( 713): Found Xposed class 'de/robv/android/xposed/XposedBridge', now initializing
03-31 14:06:52.774 I/Xposed ( 713): Loading modules from /data/app/com.ceco.nougat.gravitybox-1/base.apk
03-31 14:06:52.806 I/Xposed ( 713): Loading class com.ceco.nougat.gravitybox.GravityBox
03-31 14:06:52.819 I/Xposed ( 713): GB:Hardware: sailfish
03-31 14:06:52.819 I/Xposed ( 713): GB:Product: sailfish
03-31 14:06:52.819 I/Xposed ( 713): GB:Device manufacturer: Google
03-31 14:06:52.819 I/Xposed ( 713): GB:Device brand: google
03-31 14:06:52.819 I/Xposed ( 713): GB:Device model: Pixel
03-31 14:06:52.821 I/Xposed ( 713): GB:Device type: phone
03-31 14:06:52.821 I/Xposed ( 713): GB:Is MTK device: false
03-31 14:06:52.821 I/Xposed ( 713): GB:Is Xperia device: false
03-31 14:06:52.821 I/Xposed ( 713): GB:Is Moto XT device: false
03-31 14:06:52.821 I/Xposed ( 713): GB:Is OxygenOS ROM: false
03-31 14:06:52.822 I/Xposed ( 713): GB:Has telephony support: true
03-31 14:06:52.822 I/Xposed ( 713): GB:Has Gemini support: false
03-31 14:06:52.822 I/Xposed ( 713): GB:Android SDK: 25
03-31 14:06:52.822 I/Xposed ( 713): GB:Android Release: 7.1.2
03-31 14:06:52.822 I/Xposed ( 713): GB:ROM: N2G47O
03-31 14:06:52.822 I/Xposed ( 713): GB:Error logging: false
03-31 14:07:05.189 I/Xposed ( 1296): GB:Is AOSP forced: false
可以观察到主要涉及的文件也就是/system/framework/XposedBridge.jar，也就是前文中放到/system/framework/的XposedBridge.jar文件，可见XposedBridge.jar文件在Xposed插件的运行中起到了关键的作用。
收集特征：插件开发配置信息
根据官方tutorial，典型的插件开发流程分为：
- 加入
Xposed Framework API
- 修改
AndroidManifest.xml
- 编写
hook代码
- 将类注册到
assets/xposed_init文件中去
比如编写下述java的hook代码，最终效果就是改变系统时钟颜色：
package de.robv.android.xposed.mods.tutorial;
import static de.robv.android.xposed.XposedHelpers.findAndHookMethod;
import android.graphics.Color;
import android.widget.TextView;
import de.robv.android.xposed.IXposedHookLoadPackage;
import de.robv.android.xposed.XC_MethodHook;
import de.robv.android.xposed.callbacks.XC_LoadPackage.LoadPackageParam;
public class Tutorial implements IXposedHookLoadPackage {
public void handleLoadPackage(final LoadPackageParam lpparam) throws Throwable {
if (!lpparam.packageName.equals("com.android.systemui"))
return;
findAndHookMethod("com.android.systemui.statusbar.policy.Clock", lpparam.classLoader, "updateClock", new XC_MethodHook() {
@Override
protected void afterHookedMethod(MethodHookParam param) throws Throwable {
TextView tv = (TextView) param.thisObject;
String text = tv.getText().toString();
tv.setText(text + " :)");
tv.setTextColor(Color.RED);
}
});
}
}
可以看到引入的包都位于de.robv.android.xposed包中，当然这也是引入Xposed Framework API时被包含进项目的：
repositories {
jcenter();
}
dependencies {
provided 'de.robv.android.xposed:api:82'
}
官网最新的版本还是api-82.jar、api-source-82.jar。
下载来看下里面的内容，一个是.class字节码，一个是.java源代码而已。
随便打开个文件来康康，IXposedHookLoadPackage.java：
package de.robv.android.xposed;
import android.app.Application;
import de.robv.android.xposed.callbacks.XC_LoadPackage;
import de.robv.android.xposed.callbacks.XC_LoadPackage.LoadPackageParam;
/**
* Get notified when an app ("Android package") is loaded.
* This is especially useful to hook some app-specific methods.
*
* <p>This interface should be implemented by the module's main class. Xposed will take care of
* registering it as a callback automatically.
*/
public interface IXposedHookLoadPackage extends IXposedMod {
/**
* This method is called when an app is loaded. It's called very early, even before
* {@link Application#onCreate} is called.
* Modules can set up their app-specific hooks here.
*
* @Param lpparam Information about the app.
* @throws Throwable Everything the callback throws is caught and logged.
*/
void handleLoadPackage(LoadPackageParam lpparam) throws Throwable;
/** @hIde */
final class Wrapper extends XC_LoadPackage {
private final IXposedHookLoadPackage instance;
public Wrapper(IXposedHookLoadPackage instance) {
this.instance = instance;
}
@Override
public void handleLoadPackage(LoadPackageParam lpparam) throws Throwable {
instance.handleLoadPackage(lpparam);
}
}
}
里面的各种xposed特征字符串到处都是。
也就是说，如果我们更改了xposed的字符串特征，也要制作这样的一份api-82.jar、api-source-82.jar，供开发者编写代码时进行调用。
并且开发者在编码时，使用的系列API中，至少不存在xposed字样。
到这里正常的Xposed插件开发及使用流程中可以搜集到的特征就都有了，接下来看一个专业检测Xposed的App，看看它主要检测哪些方面。
收集特征：XposedChecker源码
作者已经将源码开源：XposedChecker，安装包位于app目录中，名字叫Xposed Checker 4.apk，先装上去跑一下，申请root权限时点击“同意”，结果如下图所示，可信度竟然5/9，我的GravityBox插件还在跑着，状态栏还变着色：
这个结果肯定是不准确的，那四个绿色的项目中，只有“检测虚拟Xposed环境”是对的，毕竟我们不是VirtualXposed，而是真实的Xposed。其他三项出现了失误，可以看看它的源码怎么写的，主要的检测逻辑位于app\src\main\java\ml\w568w\checkxposed\ui\MainActivity.java文件中，定义了以下功能：
private static final String[] CHECK_ITEM = {
"载入Xposed工具类",
"寻找特征动态链接库",
"代码堆栈寻找调起者",
"检测Xposed安装情况",
"判定系统方法调用钩子",
"检测虚拟Xposed环境",
"寻找Xposed运行库文件",
"内核查找Xposed链接库",
"环境变量特征字判断",
};
private boolean testClassLoader() {
try {
ClassLoader.getSystemClassLoader()
.loadClass("de.robv.android.xposed.XposedHelpers");
return true;
}
catch (ClassNotFoundException e) {
e.printStackTrace();
}
return false;
}
private int check2() {
return checkContains("XposedBridge") ? 1 : 0;
}
public static boolean checkContains(String paramString) {
try {
HashSet<String> localObject = new HashSet<>();
// 读取maps文件信息
BufferedReader localBufferedReader =
new BufferedReader(new FileReader("/proc/" + Process.myPid() + "/maps"));
while (true) {
String str = localBufferedReader.readLine();
if (str == null) {
break;
}
localObject.add(str.substring(str.lastIndexOf(" ") + 1));
}
//应用程序的链接库不可能是空，除非是高于7.0。。。
if (localObject.isEmpty() && Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
return true;
}
localBufferedReader.close();
for (String aLocalObject : localObject) {
if (aLocalObject.contains(paramString)) {
return true;
}
}
}
catch (Throwable ignored) {
}
return false;
}
private int check3() {
try {
throw new Exception();
}
catch (Exception e) {
StackTraceElement[] arrayOfStackTraceElement = e.getStackTrace();
for (StackTraceElement s : arrayOfStackTraceElement) {
if ("de.robv.android.xposed.XposedBridge".equals(s.getClassName())) {
return 1;
}
}
return 0;
}
}
private int check4() {
try {
List<PackageInfo> list = getPackageManager().getInstalledPackages(0);
for (PackageInfo info : list) {
if ("de.robv.android.xposed.installer".equals(info.packageName)) {
return 1;
}
if ("io.va.exposed".equals(info.packageName)) {
return 1;
}
}
}
catch (Throwable ignored) {
}
return 0;
}
private int check5() {
try {
Method method = Throwable.class.getDeclaredMethod("getStackTrace");
return Modifier.isNative(method.getModifiers()) ? 1 : 0;
}
catch (NoSuchMethodException e) {
e.printStackTrace();
}
return 0;
}
private int check6() {
return System.getProperty("vxp") != null ? 1 : 0;
}
private int check7() {
CommandResult commandResult = Shell.run("ls /system/lib");
return commandResult.isSuccessful() ? commandResult.getStdout().contains("xposed") ? 1 : 0 : 0;
}
char isXposedMaps(char * pid){
FILE * maps;
char path[80];
char * content;
strcpy (path,"/proc/");
strcat (path,pid);
strcat (path,"/maps");
if((maps=fopen(path,"r"))==NULL){
return 0;
}else{
int len=filelength(maps);
content=(char *)malloc(len);
fread(content,len,1,maps);
content[len-1]='\0';
return strstr(content,"XposedBridge")!=NULL;
}
}
private int check9() {
return System.getenv("CLASSPATH").contains("XposedBridge") ? 1 : 0;
}
收集特征：逆向分析大厂方案
以上每一篇都看过来之后，发现文章还是比较过时的，现在大部分风控都是写在so中，检测项目可能多达成百上千项，并且Ollvm甚至自家vmp来混淆下，不会让你轻易地找到并patch的；只是他们收集了环境特征后只是加密上传，并不会把app退掉让你发现而已。
针对这种加固/风控的行为特征，可能比较好的方案就是修改aosp系统源码，打更多的埋点，收集so的检测项目，形成一个checklist；或者unicorn来模拟执行，只是现在对抗unicorn的技术也越来越多，unicorn的终极形态，就是一个完整的安卓系统；所以不如直接改系统。
当然我们不用分析那么远，只需要简单修改XPOSED的字符串，过简单的根据字符串特征的XPOSED检测是没有问题的。
在下一篇中我们将介绍XPOSED框架之间的关系，以及如何编译使用原版XPOSED框架，最后一篇中再来简单更改特征。
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发表于 2020-4-5 16:09
