CISA.gov - AA21-062A Mitigate Microsoft Exchange Server Vulnerabilities
This alert references Microsoft Exchange Server vulnerabilities highlighted by CISA in Activity Alert AA21-062A. It provides indicators of compromise (IOCs) related to malicious activity exploiting these vulnerabilities. Although no specific affected versions or exploits in the wild are detailed here, the vulnerabilities relate to payload delivery and network activity targeting Exchange servers. The severity is marked as low in this data, and no patches or known exploits are currently available. European organizations using Microsoft Exchange Server should be aware of potential risks and monitor for related IOCs. Mitigation involves following CISA's detailed guidance, including applying official Microsoft patches and hardening Exchange Server configurations. Countries with high Exchange Server deployment and critical infrastructure reliance on email services are more likely to be impacted. Given the potential for network-based exploitation and payload delivery, the suggested severity is medium to ensure vigilance. Defenders should prioritize detection and response capabilities for Exchange-related threats and maintain up-to-date security posture.
AI Analysis
Technical Summary
The provided information concerns a security threat related to Microsoft Exchange Server vulnerabilities as reported by CISA in Activity Alert AA21-062A. This alert includes indicators of compromise (IOCs) associated with malicious activities exploiting these vulnerabilities, primarily involving payload delivery and network activity. Although the specific affected versions are not listed and no patches or known exploits in the wild are indicated in this data, the vulnerabilities are significant due to the critical role Exchange servers play in enterprise email infrastructure. The threat level is marked as 3 with low severity, but the absence of patch availability and known exploits suggests that this is an early-stage alert or a notification to raise awareness. The vulnerabilities could allow attackers to deliver malicious payloads remotely, potentially compromising confidentiality, integrity, and availability of email communications and related services. The alert emphasizes the importance of monitoring network activity and applying mitigation strategies as outlined by CISA and Microsoft. Given the widespread use of Microsoft Exchange Server in Europe, especially in government, finance, and large enterprises, this threat warrants attention despite the current low severity rating. The lack of detailed technical specifics in this data limits the depth of analysis but underscores the need for vigilance and proactive defense.
Potential Impact
For European organizations, exploitation of Microsoft Exchange Server vulnerabilities could lead to unauthorized access to sensitive email communications, data exfiltration, disruption of email services, and potential lateral movement within networks. This can impact confidentiality, integrity, and availability of critical business communications and operations. Organizations in sectors such as government, finance, healthcare, and critical infrastructure are particularly at risk due to their reliance on Exchange servers and the sensitive nature of their communications. Disruption or compromise could result in operational downtime, reputational damage, regulatory penalties under GDPR, and financial losses. The network-based nature of the threat means that attackers could potentially exploit these vulnerabilities remotely, increasing the risk of widespread impact if not mitigated promptly. Although no known exploits are currently reported, the potential for future exploitation necessitates preparedness.
Mitigation Recommendations
European organizations should immediately review CISA's Activity Alert AA21-062A and Microsoft’s official security advisories for detailed mitigation steps. Key actions include: 1) Applying all relevant Microsoft Exchange Server security patches as soon as they become available; 2) Implementing network segmentation to limit Exchange server exposure; 3) Enhancing monitoring for unusual network activity and payload delivery attempts targeting Exchange servers; 4) Employing intrusion detection and prevention systems tuned for Exchange-related threats; 5) Conducting regular vulnerability assessments and penetration testing focused on Exchange infrastructure; 6) Ensuring robust email filtering and anti-malware solutions are in place; 7) Restricting administrative access and enforcing multi-factor authentication for Exchange management interfaces; 8) Maintaining up-to-date backups of Exchange data to enable recovery in case of compromise; 9) Training security teams to recognize and respond to indicators of compromise related to Exchange vulnerabilities; 10) Collaborating with national cybersecurity centers and sharing threat intelligence to stay informed about emerging exploits.
Affected Countries
Germany, France, United Kingdom, Italy, Spain, Netherlands, Belgium, Sweden, Poland, Austria
Indicators of Compromise
- comment: This STIX file provides indicators of compromise (IOCs) associated with malicious activity reported in Activity Alert, AA21-062A Mitigate Microsoft Exchange Server Vulnerabilities. For more information about this activity, to include detection and mitigation recommendations, see the Activity Alert.
- hash: b75f163ca9b9240bf4b37ad92bc7556b40a17e27c2b8ed5c8991385fe07d17d0
- hash: 811157f9c7003ba8d17b45eb3cf09bef2cecd2701cedb675274949296a6a183d
- hash: 65149e036fff06026d80ac9ad4d156332822dc93142cf1a122b1841ec8de34b5
- hash: 511df0e2df9bfa5521b588cc4bb5f8c5a321801b803394ebc493db1ef3c78fa1
- hash: 4edc7770464a14f54d17f36dc9d0fe854f68b346b27b35a6f5839adf1f13f8ea
- hash: 2b6f1ebb2208e93ade4a6424555d6a8341fd6d9f60c25e44afe11008f5c1aad1
- hash: 1631a90eb5395c4e19c7dbcbf611bbe6444ff312eb7937e286e4637cb9e72944
- hash: 097549cf7d0f76f0d99edf8b2d91c60977fd6a96e4b8c3c94b0b1733dc026d3e
- ip: 91.192.103.43
- ip: 80.92.205.81
- ip: 5.2.69.14
- ip: 5.254.43.18
- ip: 211.56.98.146
- ip: 203.160.69.66
- ip: 192.81.208.169
- ip: 185.250.151.72
- ip: 167.99.168.251
- ip: 157.230.221.198
- ip: 149.28.14.163
- ip: 108.61.246.56
- ip: 104.250.191.110
- ip: 103.77.192.219
- ip: 104.140.114.110
- file: AA21-062A.stix.xml
- text: STIX 1.1
- link: https://us-cert.cisa.gov/ncas/alerts/aa21-062a
- text: Cybersecurity and Infrastructure Security (CISA) partners have observed active exploitation of vulnerabilities in Microsoft Exchange Server products. Successful exploitation of these vulnerabilities allows an unauthenticated attacker to execute arbitrary code on vulnerable Exchange Servers, enabling the attacker to gain persistent system access, as well as access to files and mailboxes on the server and to credentials stored on that system. Successful exploitation may additionally enable the attacker to compromise trust and identity in a vulnerable network. Microsoft released out-of-band patches to address vulnerabilities in Microsoft Exchange Server. The vulnerabilities impact on-premises Microsoft Exchange Servers and are not known to impact Exchange Online or Microsoft 365 (formerly O365) cloud email services. This Alert includes both tactics, techniques and procedures (TTPs) and the indicators of compromise (IOCs) associated with this malicious activity. To secure against this threat, CISA recommends organizations examine their systems for the TTPs and use the IOCs to detect any malicious activity. If an organization discovers exploitation activity, they should assume network identity compromise and follow incident response procedures. If an organization finds no activity, they should apply available patches immediately and implement the mitigations in this Alert.
CISA.gov - AA21-062A Mitigate Microsoft Exchange Server Vulnerabilities
Description
This alert references Microsoft Exchange Server vulnerabilities highlighted by CISA in Activity Alert AA21-062A. It provides indicators of compromise (IOCs) related to malicious activity exploiting these vulnerabilities. Although no specific affected versions or exploits in the wild are detailed here, the vulnerabilities relate to payload delivery and network activity targeting Exchange servers. The severity is marked as low in this data, and no patches or known exploits are currently available. European organizations using Microsoft Exchange Server should be aware of potential risks and monitor for related IOCs. Mitigation involves following CISA's detailed guidance, including applying official Microsoft patches and hardening Exchange Server configurations. Countries with high Exchange Server deployment and critical infrastructure reliance on email services are more likely to be impacted. Given the potential for network-based exploitation and payload delivery, the suggested severity is medium to ensure vigilance. Defenders should prioritize detection and response capabilities for Exchange-related threats and maintain up-to-date security posture.
AI-Powered Analysis
Technical Analysis
The provided information concerns a security threat related to Microsoft Exchange Server vulnerabilities as reported by CISA in Activity Alert AA21-062A. This alert includes indicators of compromise (IOCs) associated with malicious activities exploiting these vulnerabilities, primarily involving payload delivery and network activity. Although the specific affected versions are not listed and no patches or known exploits in the wild are indicated in this data, the vulnerabilities are significant due to the critical role Exchange servers play in enterprise email infrastructure. The threat level is marked as 3 with low severity, but the absence of patch availability and known exploits suggests that this is an early-stage alert or a notification to raise awareness. The vulnerabilities could allow attackers to deliver malicious payloads remotely, potentially compromising confidentiality, integrity, and availability of email communications and related services. The alert emphasizes the importance of monitoring network activity and applying mitigation strategies as outlined by CISA and Microsoft. Given the widespread use of Microsoft Exchange Server in Europe, especially in government, finance, and large enterprises, this threat warrants attention despite the current low severity rating. The lack of detailed technical specifics in this data limits the depth of analysis but underscores the need for vigilance and proactive defense.
Potential Impact
For European organizations, exploitation of Microsoft Exchange Server vulnerabilities could lead to unauthorized access to sensitive email communications, data exfiltration, disruption of email services, and potential lateral movement within networks. This can impact confidentiality, integrity, and availability of critical business communications and operations. Organizations in sectors such as government, finance, healthcare, and critical infrastructure are particularly at risk due to their reliance on Exchange servers and the sensitive nature of their communications. Disruption or compromise could result in operational downtime, reputational damage, regulatory penalties under GDPR, and financial losses. The network-based nature of the threat means that attackers could potentially exploit these vulnerabilities remotely, increasing the risk of widespread impact if not mitigated promptly. Although no known exploits are currently reported, the potential for future exploitation necessitates preparedness.
Mitigation Recommendations
European organizations should immediately review CISA's Activity Alert AA21-062A and Microsoft’s official security advisories for detailed mitigation steps. Key actions include: 1) Applying all relevant Microsoft Exchange Server security patches as soon as they become available; 2) Implementing network segmentation to limit Exchange server exposure; 3) Enhancing monitoring for unusual network activity and payload delivery attempts targeting Exchange servers; 4) Employing intrusion detection and prevention systems tuned for Exchange-related threats; 5) Conducting regular vulnerability assessments and penetration testing focused on Exchange infrastructure; 6) Ensuring robust email filtering and anti-malware solutions are in place; 7) Restricting administrative access and enforcing multi-factor authentication for Exchange management interfaces; 8) Maintaining up-to-date backups of Exchange data to enable recovery in case of compromise; 9) Training security teams to recognize and respond to indicators of compromise related to Exchange vulnerabilities; 10) Collaborating with national cybersecurity centers and sharing threat intelligence to stay informed about emerging exploits.
Technical Details
- Threat Level
- 3
- Analysis
- 0
- Uuid
- eb8ec4e4-ea78-4cf5-80bc-974e765f08df
- Original Timestamp
- 1615717945
Indicators of Compromise
Comment
| Value | Description | Copy |
|---|---|---|
commentThis STIX file provides indicators of compromise (IOCs) associated with malicious activity reported in Activity Alert, AA21-062A Mitigate Microsoft Exchange Server Vulnerabilities. For more information about this activity, to include detection and mitigation recommendations, see the Activity Alert. | Imported from STIX header description |
Hash
| Value | Description | Copy |
|---|---|---|
hashb75f163ca9b9240bf4b37ad92bc7556b40a17e27c2b8ed5c8991385fe07d17d0 | — | |
hash811157f9c7003ba8d17b45eb3cf09bef2cecd2701cedb675274949296a6a183d | — | |
hash65149e036fff06026d80ac9ad4d156332822dc93142cf1a122b1841ec8de34b5 | — | |
hash511df0e2df9bfa5521b588cc4bb5f8c5a321801b803394ebc493db1ef3c78fa1 | — | |
hash4edc7770464a14f54d17f36dc9d0fe854f68b346b27b35a6f5839adf1f13f8ea | — | |
hash2b6f1ebb2208e93ade4a6424555d6a8341fd6d9f60c25e44afe11008f5c1aad1 | — | |
hash1631a90eb5395c4e19c7dbcbf611bbe6444ff312eb7937e286e4637cb9e72944 | — | |
hash097549cf7d0f76f0d99edf8b2d91c60977fd6a96e4b8c3c94b0b1733dc026d3e | — |
Ip
| Value | Description | Copy |
|---|---|---|
ip91.192.103.43 | — | |
ip80.92.205.81 | — | |
ip5.2.69.14 | — | |
ip5.254.43.18 | — | |
ip211.56.98.146 | — | |
ip203.160.69.66 | — | |
ip192.81.208.169 | — | |
ip185.250.151.72 | — | |
ip167.99.168.251 | — | |
ip157.230.221.198 | — | |
ip149.28.14.163 | — | |
ip108.61.246.56 | — | |
ip104.250.191.110 | — | |
ip103.77.192.219 | — | |
ip104.140.114.110 | — |
File
| Value | Description | Copy |
|---|---|---|
fileAA21-062A.stix.xml | — |
Text
| Value | Description | Copy |
|---|---|---|
textSTIX 1.1 | — | |
textCybersecurity and Infrastructure Security (CISA) partners have observed active exploitation of vulnerabilities in Microsoft Exchange Server products. Successful exploitation of these vulnerabilities allows an unauthenticated attacker to execute arbitrary code on vulnerable Exchange Servers, enabling the attacker to gain persistent system access, as well as access to files and mailboxes on the server and to credentials stored on that system. Successful exploitation may additionally enable the attacker to compromise trust and identity in a vulnerable network. Microsoft released out-of-band patches to address vulnerabilities in Microsoft Exchange Server. The vulnerabilities impact on-premises Microsoft Exchange Servers and are not known to impact Exchange Online or Microsoft 365 (formerly O365) cloud email services.
This Alert includes both tactics, techniques and procedures (TTPs) and the indicators of compromise (IOCs) associated with this malicious activity. To secure against this threat, CISA recommends organizations examine their systems for the TTPs and use the IOCs to detect any malicious activity. If an organization discovers exploitation activity, they should assume network identity compromise and follow incident response procedures. If an organization finds no activity, they should apply available patches immediately and implement the mitigations in this Alert. | — |
Link
| Value | Description | Copy |
|---|---|---|
linkhttps://us-cert.cisa.gov/ncas/alerts/aa21-062a | — |
Threat ID: 682acdbebbaf20d303f0ef4f
Added to database: 5/19/2025, 6:20:46 AM
Last enriched: 12/24/2025, 6:15:52 AM
Last updated: 2/7/2026, 5:43:12 AM
Views: 75
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console in Console -> Billing for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.