Security Alerts

Cisco IOS and IOS XE Software Link Layer Discovery Protocol Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Link Layer Discovery Protocol (LLDP) message parser of Cisco IOS Software and Cisco IOS XE Software could allow an attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition.

This vulnerability is due to improper initialization of a buffer. An attacker could exploit this vulnerability via any of the following methods:

  • An authenticated, remote attacker could access the LLDP neighbor table via either the CLI or SNMP while the device is in a specific state.
  • An unauthenticated, adjacent attacker could corrupt the LLDP neighbor table by injecting specific LLDP frames into the network and then waiting for an administrator of the device or a network management system (NMS) managing the device to retrieve the LLDP neighbor table of the device via either the CLI or SNMP.
  • An authenticated, adjacent attacker with SNMP read-only credentials or low privileges on the device CLI could corrupt the LLDP neighbor table by injecting specific LLDP frames into the network and then accessing the LLDP neighbor table via either the CLI or SNMP.

A successful exploit could allow the attacker to cause the affected device to crash, resulting in a reload of the device.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-lldp-dos-sBnuHSjT

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-34703
Categories: Security Alerts

Cisco IOS XE SD-WAN Software Command Injection Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the CLI of Cisco IOS XE SD-WAN Software and Cisco IOS XE Software could allow an authenticated, local attacker to execute arbitrary commands with elevated privileges on an affected device.

This vulnerability is due to insufficient validation of arguments passed to certain CLI commands. An attacker could exploit this vulnerability by including malicious input in the argument of an affected command. A successful exploit could allow the attacker to execute arbitrary commands with elevated privileges on the underlying operating system. An attacker would need valid user credentials to exploit this vulnerability.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ioxesdwan-clicmdinj-7bYX5k3

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-34729
Categories: Security Alerts

Cisco IOS XE SD-WAN Software Buffer Overflow Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the vDaemon process in Cisco IOS XE SD-WAN Software could allow an unauthenticated, remote attacker to cause a buffer overflow on an affected device.

This vulnerability is due to insufficient bounds checking when an affected device processes traffic. An attacker could exploit this vulnerability by sending crafted traffic to the device. A successful exploit could allow the attacker to cause a buffer overflow and possibly execute arbitrary commands with root-level privileges, or cause the device to reload, which could result in a denial of service condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxesdwan-rbuffover-vE2OB6tp

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Critical
CVE: CVE-2021-34727
Categories: Security Alerts

Cisco IOS XE SD-WAN Software Privilege Escalation Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Cisco IOS XE SD-WAN Software CLI could allow an authenticated, local attacker to elevate privileges and execute arbitrary code on the underlying operating system as the root user. An attacker must be authenticated on an affected device as a PRIV15 user.

This vulnerability is due to insufficient file system protection and the presence of a sensitive file in the bootflash directory on an affected device. An attacker could exploit this vulnerability by overwriting an installer file stored in the bootflash directory with arbitrary commands that can be executed with root-level privileges. A successful exploit could allow the attacker to read and write changes to the configuration database on the affected device.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxesdwan-privesc-VP4FG3jD

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-34724
Categories: Security Alerts

Cisco IOS XE SD-WAN Software Arbitrary File Overwrite Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in a specific CLI command that is run on Cisco IOS XE SD-WAN Software could allow an authenticated, local attacker to overwrite arbitrary files in the configuration database of an affected device.

This vulnerability is due to insufficient validation of specific CLI command parameters. An attacker could exploit this vulnerability by issuing that command with specific parameters. A successful exploit could allow the attacker to overwrite the content of the configuration database and gain root-level access to an affected device.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxesdwan-arbfileov-MVOF3ZZn

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-34723
Categories: Security Alerts

Cisco IOS XE Software H.323 Application Level Gateway Bypass Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the H.323 application level gateway (ALG) used by the Network Address Translation (NAT) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass the ALG.

This vulnerability is due to insufficient data validation of traffic that is traversing the ALG. An attacker could exploit this vulnerability by sending crafted traffic to a targeted device. A successful exploit could allow the attacker to bypass the ALG and open connections that should not be allowed to a remote device located behind the ALG.

Note: This vulnerability has been publicly discussed as NAT Slipstreaming

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-h323alg-bypass-4vy2MP2Q

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-1616
Categories: Security Alerts

Cisco Embedded Wireless Controller Software for Catalyst Access Points Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the packet processing functionality of Cisco Embedded Wireless Controller (EWC) Software for Catalyst Access Points (APs) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected AP.

This vulnerability is due to insufficient buffer allocation. An attacker could exploit this vulnerability by sending crafted traffic to an affected device. A successful exploit could allow the attacker to exhaust available resources and cause a DoS condition on an affected AP, as well as a DoS condition for client traffic traversing the AP.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-ewc-dos-g6JruHRT

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-1615
Categories: Security Alerts

Multiple Cisco Operating Systems Unidirectional Link Detection Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software, Cisco IOS Software, Cisco IOS XE Software, Cisco IOS XR Software, and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause an affected device to reload.

This vulnerability is due to improper input validation of the UDLD packets. An attacker could exploit this vulnerability by sending specifically crafted UDLD packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition.

Note: The UDLD feature is disabled by default, and the conditions to exploit this vulnerability are strict. An attacker must have full control of a directly connected device. On Cisco IOS XR devices, the impact is limited to the reload of the UDLD process.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-34714
Categories: Security Alerts

Cisco IOS and IOS XE Software IKEv2 AutoReconnect Feature Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) support for the AutoReconnect feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to exhaust the free IP addresses from the assigned local pool.

This vulnerability occurs because the code does not release the allocated IP address under certain failure conditions. An attacker could exploit this vulnerability by trying to connect to the device with a non-AnyConnect client. A successful exploit could allow the attacker to exhaust the IP addresses from the assigned local pool, which prevents users from logging in and leads to a denial of service (DoS) condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ikev2-ebFrwMPr

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-1620
Categories: Security Alerts

Cisco IOS and IOS XE Software FXO Interface Destination Pattern Bypass Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Voice Telephony Service Provider (VTSP) service of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to bypass configured destination patterns and dial arbitrary numbers.

This vulnerability is due to insufficient validation of dial strings at Foreign Exchange Office (FXO) interfaces. An attacker could exploit this vulnerability by sending a malformed dial string to an affected device via either the ISDN protocol or SIP. A successful exploit could allow the attacker to conduct toll fraud, resulting in unexpected financial impact to affected customers.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fxo-pattern-bypass-jUXgygYv

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-34705
Categories: Security Alerts

Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers IPv6 Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in IPv6 traffic processing of Cisco IOS XE Wireless Controller Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, adjacent attacker to cause a Layer 2 (L2) loop in a configured VLAN, resulting in a denial of service (DoS) condition for that VLAN.

The vulnerability is due to a logic error when processing specific link-local IPv6 traffic. An attacker could exploit this vulnerability by sending a crafted IPv6 packet that would flow inbound through the wired interface of an affected device. A successful exploit could allow the attacker to cause traffic drops in the affected VLAN, thus triggering the DoS condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-ipv6-dos-NMYeCnZv

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-34767
Categories: Security Alerts

Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers EoGRE Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in Ethernet over GRE (EoGRE) packet processing of Cisco IOS XE Wireless Controller Software for the Cisco Catalyst 9800 Family Wireless Controller, Embedded Wireless Controller, and Embedded Wireless on Catalyst 9000 Series Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

This vulnerability is due to improper processing of malformed EoGRE packets. An attacker could exploit this vulnerability by sending malicious packets to the affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-gre-6u4ELzAT

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-1611
Categories: Security Alerts

Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Remote Code Execution Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, remote attacker to execute arbitrary code with administrative privileges or cause a denial of service (DoS) condition on an affected device.

The vulnerability is due to a logic error that occurs during the validation of CAPWAP packets. An attacker could exploit this vulnerability by sending a crafted CAPWAP packet to an affected device. A successful exploit could allow the attacker to execute arbitrary code with administrative privileges or cause the affected device to crash and reload, resulting in a DoS condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-capwap-rce-LYgj8Kf

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Critical
CVE: CVE-2021-34770
Categories: Security Alerts

Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Denial of Service Vulnerabilities

Cisco Security Advisories - Wed, 2021-09-22 16:00

Multiple vulnerabilities in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

These vulnerabilities are due to insufficient validation of CAPWAP packets. An attacker could exploit the vulnerabilities by sending a malformed CAPWAP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-capwap-dos-gmNjdKOY

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-1565,CVE-2021-34768,CVE-2021-34769
Categories: Security Alerts

Cisco Access Points SSH Management Privilege Escalation Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the SSH management feature of multiple Cisco Access Points (APs) platforms could allow a local, authenticated user to modify files on the affected device and possibly gain escalated privileges.

The vulnerability is due to improper checking on file operations within the SSH management interface. A network administrator user could exploit this vulnerability by accessing an affected device through SSH management to make a configuration change. A successful exploit could allow the attacker to gain privileges equivalent to the root user.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cisco-ap-LLjsGxv


Security Impact Rating: High
CVE: CVE-2021-1419
Categories: Security Alerts

Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers Simple Network Management Protocol Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Simple Network Management Protocol (SNMP) punt handling function of Cisco cBR-8 Converged Broadband Routers could allow an authenticated, remote attacker to overload a device punt path, resulting in a denial of service (DoS) condition.

This vulnerability is due to the punt path being overwhelmed by large quantities of SNMP requests. An attacker could exploit this vulnerability by sending a large number of SNMP requests to an affected device. A successful exploit could allow the attacker to overload the device punt path, resulting in a DoS condition.

Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cbr8snmp-zGjkZ9Fc

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-1623
Categories: Security Alerts

Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers Common Open Policy Service Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the Common Open Policy Service (COPS) of Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, remote attacker to cause resource exhaustion, resulting in a denial of service (DoS) condition.

This vulnerability is due to a deadlock condition in the code when processing COPS packets under certain conditions. An attacker could exploit this vulnerability by sending COPS packets with high burst rates to an affected device. A successful exploit could allow the attacker to cause the CPU to consume excessive resources, which prevents other control plane processes from obtaining resources and results in a DoS. 

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cbr8-cops-Vc2ZsJSx

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: High
CVE: CVE-2021-1622
Categories: Security Alerts

Cisco ASR 900 and ASR 920 Series Aggregation Services Routers Access Control List Bypass Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the access control list (ACL) programming of Cisco ASR 900 and ASR 920 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to bypass a configured ACL.

This vulnerability is due to incorrect programming of hardware when an ACL is configured using a method other than the configuration CLI. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass an ACL on the affected device.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr900acl-UeEyCxkv

This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.


Security Impact Rating: Medium
CVE: CVE-2021-34696
Categories: Security Alerts

Cisco Aironet Access Points WLAN Control Protocol Packet Buffer Leak Denial of Service Vulnerability

Cisco Security Advisories - Wed, 2021-09-22 16:00

A vulnerability in the WLAN Control Protocol (WCP) implementation for Cisco Aironet Access Point (AP) software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. 

This vulnerability is due to incorrect error handling when an affected device receives an unexpected 802.11 frame. An attacker could exploit this vulnerability by sending certain 802.11 frames over the wireless network to an interface on an affected AP. A successful exploit could allow the attacker to cause a packet buffer leak. This could eventually result in buffer allocation failures, which would trigger a reload of the affected device.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-airo-wpa-pktleak-dos-uSTyGrL


Security Impact Rating: High
CVE: CVE-2021-34740
Categories: Security Alerts

AA21-265A: Conti Ransomware

US-CERT - Wed, 2021-09-22 10:00
Original release date: September 22, 2021
Summary

Immediate Actions You Can Take Now to Protect Against Conti Ransomware
• Use multi-factor authentication.
• Segment and segregate networks and functions.
• Update your operating system and software.

Note: This Alert uses the MITRE Adversarial Tactics, Techniques, and Common Knowledge (ATT&CK®) framework, version 9. See the ATT&CK for Enterprise for all referenced threat actor tactics and techniques.

The Cybersecurity and Infrastructure Security Agency (CISA) and the Federal Bureau of Investigation (FBI) have observed the increased use of Conti ransomware in more than 400 attacks on U.S. and international organizations. In typical Conti ransomware attacks, malicious cyber actors steal files, encrypt servers and workstations, and demand a ransom payment. 

To secure systems against Conti ransomware, CISA, FBI, and the National Security Agency (NSA) recommend implementing the mitigation measures described in this Advisory, which include requiring multi-factor authentication (MFA), implementing network segmentation, and keeping operating systems and software up to date.

Click here for a PDF version of this report.

Click here for indicators of compromise (IOCs) in STIX format.

Technical Details

While Conti is considered a ransomware-as-a-service (RaaS) model ransomware variant, there is variation in its structure that differentiates it from a typical affiliate model. It is likely that Conti developers pay the deployers of the ransomware a wage rather than a percentage of the proceeds used by affiliate cyber actors and receives a share of the proceeds from a successful attack. 

Conti actors often gain initial access [TA0001] to networks through:

  • Spearphishing campaigns using tailored emails that contain malicious attachments [T1566.001] or malicious links [T1566.002];
    • Malicious Word attachments often contain embedded scripts that can be used to download or drop other malware—such as TrickBot and IcedID, and/or Cobalt Strike—to assist with lateral movement and later stages of the attack life cycle with the eventual goal of deploying Conti ransomware. [1],[2],[3]
  • Stolen or weak Remote Desktop Protocol (RDP) credentials [T1078].[4]
  • Phone calls;
  • Fake software promoted via search engine optimization;
  • Other malware distribution networks (e.g., ZLoader); and
  • Common vulnerabilities in external assets.

In the execution phase [TA0002], actors run a getuid payload before using a more aggressive payload to reduce the risk of triggering antivirus engines. CISA and FBI have observed Conti actors using Router Scan, a penetration testing tool, to maliciously scan for and brute force [T1110] routers, cameras, and network-attached storage devices with web interfaces. Additionally, actors use Kerberos attacks [T1558.003] to attempt to get the Admin hash to conduct brute force attacks.

Conti actors are known to exploit legitimate remote monitoring and management software and remote desktop software as backdoors to maintain persistence [TA0003] on victim networks.[5] The actors use tools already available on the victim network—and, as needed, add additional tools, such as Windows Sysinternals and Mimikatz—to obtain users’ hashes and clear-text credentials, which enable the actors to escalate privileges [TA0004] within a domain and perform other post-exploitation and lateral movement tasks [TA0008]. In some cases, the actors also use TrickBot malware to carry out post-exploitation tasks.

According to a recently leaked threat actor “playbook,” [6] Conti actors also exploit vulnerabilities in unpatched assets, such as the following, to escalate privileges [TA0004] and move laterally [TA0008] across a victim’s network:

  • 2017 Microsoft Windows Server Message Block 1.0 server vulnerabilities; [7]
  • "PrintNightmare" vulnerability (CVE-2021-34527) in Windows Print spooler [8] service; and
  • "Zerologon" vulnerability (CVE-2020-1472) in Microsoft Active Directory Domain Controller systems.[9]

Artifacts leaked with the playbook identify four Cobalt Strike server Internet Protocol (IP) addresses Conti actors previously used to communicate with their command and control (C2) server.

  • 162.244.80[.]235
  • 85.93.88[.]165
  • 185.141.63[.]120
  • 82.118.21[.]1

CISA and FBI have observed Conti actors using different Cobalt Strike server IP addresses unique to different victims.

Conti actors often use the open-source Rclone command line program for data exfiltration [TA0010]. After the actors steal and encrypt the victim's sensitive data [T1486], they employ a double extortion technique in which they demand the victim pay a ransom for the release of the encrypted data and threaten the victim with public release of the data if the ransom is not paid.

MITRE ATT&CK Techniques

Conti ransomware uses the ATT&CK techniques listed in table 1.

Table 1: Conti ATT&CK techniques for enterprise Initial Access Technique Title ID Use Valid Accounts T1078 Conti actors have been observed gaining unauthorized access to victim networks through stolen Remote Desktop Protocol (RDP) credentials.  Phishing: Spearphishing Attachment  T1566.001 Conti ransomware can be delivered using TrickBot malware, which is known to use an email with an Excel sheet containing a malicious macro to deploy the malware. Phishing: Spearphishing Link  T1566.002 Conti ransomware can be delivered using TrickBot, which has been delivered via malicious links in phishing emails. Execution Technique Title ID Use Command and Scripting Interpreter: Windows Command Shell  T1059.003 Conti ransomware can utilize command line options to allow an attacker control over how it scans and encrypts files. Native Application Programming Interface (API)  T1106 Conti ransomware has used API calls during execution. Persistence Technique Title ID Use Valid Accounts T1078 Conti actors have been observed gaining unauthorized access to victim networks through stolen RDP credentials.  External Remote Services T1133 Adversaries may leverage external-facing remote services to initially access and/or persist within a network. Remote services such as virtual private networks (VPNs), Citrix, and other access mechanisms allow users to connect to internal enterprise network resources from external locations. There are often remote service gateways that manage connections and credential authentication for these services. Services such as Windows Remote Management can also be used externally. Privilege Escalation Technique Title ID Use Process Injection: Dynamic-link Library Injection T1055.001 Conti ransomware has loaded an encrypted dynamic-link library (DLL) into memory and then executes it.  Defense Evasion Technique Title ID Use Obfuscated Files or Information  T1027 Conti ransomware has encrypted DLLs and used obfuscation to hide Windows API calls. Process Injection: Dynamic-link Library Injection T1055.001 Conti ransomware has loaded an encrypted DLL into memory and then executes it. Deobfuscate/Decode Files or Information  T1140 Conti ransomware has decrypted its payload using a hardcoded AES-256 key. Credential Access Technique Title ID Use Brute Force T1110 Conti actors use legitimate tools to maliciously scan for and brute force routers, cameras, and network-attached storage devices with web interfaces. Steal or Forge Kerberos Tickets: Kerberoasting T1558.003 Conti actors use Kerberos attacks to attempt to get the Admin hash. System Network Configuration Discovery  T1016 Conti ransomware can retrieve the ARP cache from the local system by using the GetIpNetTable() API call and check to ensure IP addresses it connects to are for local, non-internet systems. System Network Connections Discovery  T1049 Conti ransomware can enumerate routine network connections from a compromised host. Process Discovery T1057 Conti ransomware can enumerate through all open processes to search for any that have the string sql in their process name. File and Directory Discovery  T1083 Conti ransomware can discover files on a local system. Network Share Discovery T1135 Conti ransomware can enumerate remote open server message block (SMB) network shares using NetShareEnum(). Lateral Movement Technique Title ID Use Remote Services: SMB/Windows Admin Shares  T1021.002 Conti ransomware can spread via SMB and encrypts files on different hosts, potentially compromising an entire network. Taint Shared Content T1080 Conti ransomware can spread itself by infecting other remote machines via network shared drives. Impact Technique Title ID Use Data Encrypted for Impact T1486 Conti ransomware can use CreateIoCompletionPort(), PostQueuedCompletionStatus(), and GetQueuedCompletionPort() to rapidly encrypt files, excluding those with the extensions of .exe, .dll, and .lnk. It has used a different AES-256 encryption key per file with a bundled RAS-4096 public encryption key that is unique for each victim. Conti ransomware can use "Windows Restart Manager" to ensure files are unlocked and open for encryption. Service Stop T1489 Conti ransomware can stop up to 146 Windows services related to security, backup, database, and email solutions through the use of net stop. Inhibit System Recovery T1490 Conti ransomware can delete Windows Volume Shadow Copies using vssadmin. Mitigations

CISA, FBI, and NSA recommend that network defenders apply the following mitigations to reduce the risk of compromise by Conti ransomware attacks.

Use multi-factor authentication. Implement network segmentation and filter traffic.
  • Implement and ensure robust network segmentation between networks and functions to reduce the spread of the ransomware. Define a demilitarized zone that eliminates unregulated communication between networks.
  • Filter network traffic to prohibit ingress and egress communications with known malicious IP addresses. 
  • Enable strong spam filters to prevent phishing emails from reaching end users. Implement a user training program to discourage users from visiting malicious websites or opening malicious attachments. Filter emails containing executable files to prevent them from reaching end users.
  • Implement a URL blocklist and/or allowlist to prevent users from accessing malicious websites.
Scan for vulnerabilities and keep software updated. 
  • Set antivirus/antimalware programs to conduct regular scans of network assets using up-to-date signatures. 
  • Upgrade software and operating systems, applications, and firmware on network assets in a timely manner. Consider using a centralized patch management system. 
Remove unnecessary applications and apply controls.
  • Remove any application not deemed necessary for day-to-day operations. Conti threat actors leverage legitimate applications—such as remote monitoring and management software and remote desktop software applications—to aid in the malicious exploitation of an organization’s enterprise. 
  • Investigate any unauthorized software, particularly remote desktop or remote monitoring and management software.
  • Implement application allowlisting, which only allows systems to execute programs known and permitted by the organization's security policy. Implement software restriction policies (SRPs) or other controls to prevent programs from executing from common ransomware locations, such as temporary folders supporting popular internet browsers or compression/decompression programs.
  • Implement execution prevention by disabling macro scripts from Microsoft Office files transmitted via email. Consider using Office Viewer software to open Microsoft Office files transmitted via email instead of full Microsoft Office suite applications.
  • See the joint Alert, Publicly Available Tools Seen in Cyber Incidents Worldwide—developed by CISA and the cybersecurity authorities of Australia, Canada, New Zealand, and the United Kingdom—for guidance on detection and protection against malicious use of publicly available tools.
Implement endpoint and detection response tools. 
  • Endpoint and detection response tools allow a high degree of visibility into the security status of endpoints and can help effectively protect against malicious cyber actors. 
Limit access to resources over the network, especially by restricting RDP. 
  • After assessing risks, if RDP is deemed operationally necessary, restrict the originating sources and require multi-factor authentication.
Secure user accounts.
  • Regularly audit administrative user accounts and configure access controls under the principles of least privilege and separation of duties.
  • Regularly audit logs to ensure new accounts are legitimate users.

Review CISA’s APTs Targeting IT Service Provider Customers guidance for additional mitigations specific to IT Service Providers and their customers.

Use the Ransomware Response Checklist in case of infection.

If a ransomware incident occurs at your organization, CISA, FBI, and NSA recommend the following actions:

CISA, FBI, and NSA strongly discourage paying a ransom to criminal actors. Paying a ransom may embolden adversaries to target additional organizations, encourage other criminal actors to engage in the distribution of ransomware, and/or may fund illicit activities. Paying the ransom also does not guarantee that a victim’s files will be recovered.

Additional Resources Free Cyber Hygiene Services

CISA offers a range of no-cost cyber hygiene services to help organizations assess, identify, and reduce their exposure to threats, including ransomware. By requesting these services, organizations of any size could find ways to reduce their risk and mitigate attack vectors.

StopRansomware.gov 

The StopRansomware.gov webpage is an interagency resource that provides guidance on ransomware protection, detection, and response. This includes ransomware alerts, reports, and resources from CISA and other federal partners, including:

Rewards for Justice Reporting

The U.S. Department of State’s Rewards for Justice (RFJ) program offers a reward of up to $10 million for reports of foreign government malicious activity against U.S. critical infrastructure. See the RFJ website for more information and how to report information securely.

Contact Information

To report suspicious or criminal activity related to information found in this Joint Cybersecurity Advisory, contact your local FBI field office at www.fbi.gov/contact-us/field-offices, or the FBI’s 24/7 Cyber Watch (CyWatch) at (855) 292-3937 or by e-mail at CyWatch@fbi.gov. When available, please include the following information regarding the incident: date, time, and location of the incident; type of activity; number of people affected; type of equipment used for the activity; the name of the submitting company or organization; and a designated point of contact. If you have any further questions related to this Joint Cybersecurity Advisory, or to request incident response resources or technical assistance related to these threats, contact CISA at CISAServiceDesk@cisa.dhs.gov. For NSA client requirements or general cybersecurity inquiries, contact the NSA Cybersecurity Requirements Center at 410-854-4200 or Cybersecurity_Requests@nsa.gov.

References Revisions
  • September 22, 2021: Initial Version

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