Kyle Zeng discovered that the Network Queuing and Scheduling subsystem of
the Linux kernel did not properly perform reference counting in some
situations, leading to a use-after-free vulnerability. A local attacker
could use this to cause a denial of service (system crash) or execute
arbitrary code.
FortiGuard Labs is aware of a relatively new ransomware family “BlackByte” is in the wild, infecting organizations around the globe. BlackByte was first observed as early as July 2021. In February 2022, the Federal Bureau of Investigation (FBI) and the U.S. Secret Service (USSS) issued a joint advisory that “multiple US and foreign businesses, including entities in at least three US critical infrastructure sectors (government facilities, financial, and food & agriculture) were targeted by BlackByte ransomware affiliates. In common with other ransomware, BlackByte encrypts and steals files on the compromised machines, and demands ransom from the victim to recover the files and not to leak the stolen information to the public.Why is this Significant?This is significant as the BlackByte ransomware family reportedly compromised organizations around the globe including multiple US and foreign businesses and US critical infrastructure sectors. Also, ProxyShell, an exploit attack chain involving three vulnerabilities in Microsoft Exchange Server, widely used in enterprise email application, were reported to have been used as an infection vector. Microsoft issued patches for ProxyShell in May and July 2021. BlackByte ransomware infection may indicate that some organizations have not yet applied those fixes or workaround.FortiGuard Labs previously published multiple Threat Signals on ProxyShell. See the Appendix section for links to New Threat Actor Leverages ProxyShell Exploit to Serve RansomwareVulnerable Microsoft Exchange Servers Actively Scanned for ProxyShellBrand New LockFile Ransomware Distributed Through ProxyShell and PetitPotamWhat is BlackByte?BlackByte is a ransomware-as-a-service (RaaS), which runs a business of leasing necessary ransomware services to its affiliates. Such ransomware services including developing ransomware, creating and maintaining necessary infrastructures (i.e., ransom payment portal), ransom negotiation with victims as well as provides support service to the affiliates. Attacks are typically carried out by BlackByte affiliates, who rent and use those services. Once a victim is compromised and ransom is paid, BlackByte developers take a portion of the ransom as a service fee.How does the Attack Work?Typically attacks that deliver ransomware arrive in emails, however the join advisory reported that BlackByte threat actors, in some case, exploited known Microsoft Exchange Server vulnerabilities including ProxyShell to gain access to the victim’s network. Once the attacker gains a foothold in the victim’s network, the attacker deploys tools such as oft-abused Cobalt Strike to move laterally across the network and escalate privileges before exfiltrating and encrypting files. Some BlackByte ransomware variants may have worm functionality, which allows itself to self-propagate through the victim’s network.Files that are encrypted by BlackByte ransomware typically have a “.blackbyte” file extension.BlackByte ransomware reportedly avoids encrypting files if the ransomware detects compromised systems that use Russian and ex-USSR languages.What is ProxyShell?ProxyShell is a name for a Microsoft Exchange Server exploit chain (CVE-2021-34473, CVE-2021-34523 and CVE-2021-31207) that allows an attacker to bypass ACL controls, elevate privileges and execute remote code on the compromised system.What is the Status of Coverage?FortiGuard Labs provides the following AV coverage against currently available Indicator-of-Compromises (IOCs) associated with BlackByte ransomware:RTF/BlackByte.DC56!tr.ransomW64/BlackByte.DC56!tr.ransomW32/Agent.CH!trW32/CobaltStrike.NV!trJS/Agent.49CC!trW32/PossibleThreatFortiGuard Labs provides the following IPS coverage against three vulnerabilities that are leveraged in ProxyShell:MS.Exchange.Server.CVE-2021-34473.Remote.Code.Execution (CVE-2021-34473)MS.Exchange.Server.Common.Access.Token.Privilege.Elevation (CVE-2021-34523)MS.Exchange.MailboxExportRequest.Arbitrary.File.Write (CVE-2021-31207)FortiEDR detects and blocks ProxyShell attacks out of the box without any prior knowledge or special configuration beforehand.Any Other Suggested Mitigation?Due to the ease of disruption and potential for damage to daily operations, reputation, and unwanted release of personally identifiable information (PII), etc., it is important to keep all AV and IPS signatures up to date. It is also important to ensure that all known vendor vulnerabilities within an organization are addressed and updated to protect against attackers establishing a foothold within a network.Also – organizations are encouraged to conduct ongoing training sessions to educate and inform personnel about the latest phishing/spearphishing attacks. They also need to encourage employees to never open attachments from someone they don’t know, and to always treat emails from unrecognized/untrusted senders with caution. Since it has been reported that various phishing and spearphishing attacks have been delivered via social engineering distribution mechanisms, it is crucial that end users within an organization be made aware of the various types of attacks being delivered. This can be accomplished through regular training sessions and impromptu tests using predetermined templates by an organizations’ internal security department. Simple user awareness training on how to spot emails with malicious attachments or links could also help prevent initial access into the network.Disconnect vulnerable Exchange servers from the internet until a patch can be applied.
FortiGuard Labs is aware that a new Remote Access Trojan (RAT) called Nerbian RAT was delivered to the targets via COVID-19 and World Health Organization (WHO) themed emails. Nerbian RAT is written in the Go programming language and performs keylogging and screen capture on the compromised machine.Why is this Significant?This is significant because Nerbrian RAT was delivered through emails that leverages COVID-19 and World Health Organization (WHO) themed lures that are still effective today to COVID themed to compel unsuspecting victims to open malicious attachments. The RAT is also capable of stealing sensitive information from the compromised machine through keylogging and screen capture.What is Nerbian RAT?Nerbian RAT is a Remote Access Trojan and is written in the Go programming language. The malware was delivered to the target through COVID-19 and WHO themed emails such as the following:The attached document file contains malicious macros, which downloads a dropper file after macros are enabled. The dropper performs anti-reversing and anti-VM checks before launching Nerbian RAT. The malware has an encrypted configuration file containing information such which Command and Control (C2) servers to connect to and connection intervals, how many times the RAT tries to transfer files and C2 backup domains.The malware performs typical RAT activities such as keylogging and screen capture.How Widespread is the Malware?The malware was reportedly to have been observed in Italy, Spain, and the United Kingdom. What is the Status of Coverage?FortiGuard Labs provides the following AV coverage against known samples of Nerbian RAT and associated files:VBA/Agent.XSQ!tr.dldrBAT/NerbianRAT.D!trMalicious_Behavior.SBRiskware/ApplicationW32/PossibleThreatPossibleThreat.PALLAS.HAll network IOC’s are blocked by the WebFiltering client.
Kyle Zeng discovered that the Network Queuing and Scheduling subsystem of
the Linux kernel did not properly perform reference counting in some
situations, leading to a use-after-free vulnerability. A local attacker
could use this to cause a denial of service (system crash) or execute
arbitrary code. (CVE-2022-29581)
Bing-Jhong Billy Jheng discovered that the io_uring subsystem in the Linux
kernel contained in integer overflow. A local attacker could use this to
cause a denial of service (system crash) or execute arbitrary code.
(CVE-2022-1116)
Jann Horn discovered that the Linux kernel did not properly enforce seccomp
restrictions in some situations. A local attacker could use this to bypass
intended seccomp sandbox restrictions. (CVE-2022-30594)
Kyle Zeng discovered that the Network Queuing and Scheduling subsystem of
the Linux kernel did not properly perform reference counting in some
situations, leading to a use-after-free vulnerability. A local attacker
could use this to cause a denial of service (system crash) or execute
arbitrary code. (CVE-2022-29581)
Jann Horn discovered that the Linux kernel did not properly enforce seccomp
restrictions in some situations. A local attacker could use this to bypass
intended seccomp sandbox restrictions. (CVE-2022-30594)
The AGG Software Web Server version 4.0.40.1014 and prior is vulnerable to cross-site scripting, which may allow an attacker to remotely execute arbitrary code.
A vulnerability in the Spectrum Scale 5.1 core component and IBM Elastic Storage System 6.1 could allow unauthorized access to user data or injection of arbitrary data in the communication protocol. IBM X-Force ID: 191600.
A large number of security issues were discovered in the WebKitGTK Web and
JavaScript engines. If a user were tricked into viewing a malicious
website, a remote attacker could exploit a variety of issues related to web
browser security, including cross-site scripting attacks, denial of service
attacks, and arbitrary code execution.
USN-5404-1 addressed a vulnerability in Rsyslog. This update
provides the corresponding update for Ubuntu 16.04 ESM.
Original advisory details:
Pieter Agten discovered that Rsyslog incorrectly handled certain requests.
An attacker could possibly use this issue to cause a crash.
A vulnerability was found in Telecommunication Software SAMwin Contact Center Suite 5.1. It has been rated as critical. Affected by this issue is the function getCurrentDBVersion in the library SAMwinLIBVB.dll of the credential handler. Authentication is possible with hard-coded credentials. Upgrading to version 6.2 is able to address this issue. It is recommended to upgrade the affected component.
