Home News Chile’s bank regulator shares IOCs after Microsoft Exchange hack

    Chile’s bank regulator shares IOCs after Microsoft Exchange hack


    Microsoft Exchange

    Chile’s Comisión para el Mercado Financiero (CMF) has disclosed that their Microsoft Alternate server was compromised by means of the not too long ago disclosed ProxyLogon vulnerabilities.

    The CMF operates underneath the Ministry of Finance and is the regulator and inspector for banks and monetary establishments in Chile.

    This week, CMF disclosed that they suffered a cyberattack after menace actors exploited the recently disclosed ProxyLogon vulnerabilities of their Microsoft Alternate servers to put in internet shells and try to steal credentials.

    “The Fee for the Monetary Market (CMF) updates info on the operational incident reported yesterday, attributable to vulnerabilities within the Microsoft Alternate electronic mail platform.”

    “The analyzes carried out by the knowledge safety and know-how space of the CMF, along with exterior specialised help, have to date dismissed the presence of a ransomware and point out that the incident could be restricted to the Microsoft Alternate platform,” disclosed the Comisión para el Mercado Financiero.

    CMF additional states that they’re investigating the breach and have been in touch with the Pc Safety Incident Response Staff (CSIRT) of the Ministry of Finance.

    CMF shares IOCs of their assault

    To help safety professionals and different Microsoft Alternate directors, the CMF has launched IOCs of internet shells and a batch file discovered on their compromised server.

    • 0b15c14d0f7c3986744e83c208429a78769587b5: error_page.aspx (China Chopper internet shell)
    • bcb42014b8dd9d9068f23c573887bf1d5c2fc00e: supp0rt.aspx (China Chopper internet shell)
    • 0aa3cda37ab80bbe30fa73a803c984b334d73894: take a look at.bat (batch file to dump lsass.exe)

    Whereas indicators of compromise (IOC) may have completely different file hashes for every sufferer, in lots of assaults, the file names have been the identical.

    Internet shells utilizing the names ‘error_page.asp’ and ‘supp0rt.aspx’ have been utilized in quite a few ProxyLogon assaults, and for probably the most are half, are an identical with just a few modifications particular to the sufferer.

    These recordsdata are Microsoft Alternate Offline Handle Books (OAB), whose ExternalUrl setting has been modified to the China Chopper web shell. This internet shell permits menace actors to execute instructions on the compromised Microsoft Alternate server remotely by visiting the URL configured within the ExternalURL setting.

    Microsoft Exchange Offline Address Books (OAB) with web shell
    Microsoft Alternate Offline Handle Books (OAB) with internet shell

    The batch file, take a look at.bat, can also be generally seen in ProxyLogon assaults and is used to dump the LSASS course of’s reminiscence to reap Home windows area credentials. The batch file additionally exports an inventory of customers on the Home windows area.

    The command proven beneath will use the comsvcs.dll LOLBin to dump LSASS’ reminiscence to a file within the IIS server’s wwwroot. It then makes use of dsquery to export an inventory of customers within the Home windows area to a file.

    These recordsdata are then zipped up within the wwwroot to be downloaded remotely by the menace actors.

    Dumping the memory of the LSASS process
    Dumping the reminiscence of the LSASS course of

    Whereas most Microsoft Alternate assaults have been deploying internet shells, harvesting credentials, and stealing mailboxes, some assaults are additionally putting in cryptominers, and extra not too long ago, the DearCry ransomware on exploited servers.

    To assist directors discover malicious recordsdata dropped in these assaults, Microsoft has launched a script that searches Microsoft Exchange logs for IOCs and has updated their Microsoft Safety Scanner (MSERT) to detect recognized internet shells.

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