ID CVE-2017-16944
Summary The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function.
References
Vulnerable Configurations
  • cpe:2.3:a:exim:exim:4.88
    cpe:2.3:a:exim:exim:4.88
  • cpe:2.3:a:exim:exim:4.89
    cpe:2.3:a:exim:exim:4.89
  • Debian Linux 9.0
    cpe:2.3:o:debian:debian_linux:9.0
CVSS
Base: 5.0
Impact:
Exploitability:
CWE CWE-400
CAPEC
  • XML Ping of the Death
    An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
  • XML Entity Expansion
    An attacker submits an XML document to a target application where the XML document uses nested entity expansion to produce an excessively large output XML. XML allows the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
  • Inducing Account Lockout
    An attacker leverages the security functionality of the system aimed at thwarting potential attacks to launch a denial of service attack against a legitimate system user. Many systems, for instance, implement a password throttling mechanism that locks an account after a certain number of incorrect log in attempts. An attacker can leverage this throttling mechanism to lock a legitimate user out of their own account. The weakness that is being leveraged by an attacker is the very security feature that has been put in place to counteract attacks.
  • Violating Implicit Assumptions Regarding XML Content (aka XML Denial of Service (XDoS))
    XML Denial of Service (XDoS) can be applied to any technology that utilizes XML data. This is, of course, most distributed systems technology including Java, .Net, databases, and so on. XDoS is most closely associated with web services, SOAP, and Rest, because remote service requesters can post malicious XML payloads to the service provider designed to exhaust the service provider's memory, CPU, and/or disk space. The main weakness in XDoS is that the service provider generally must inspect, parse, and validate the XML messages to determine routing, workflow, security considerations, and so on. It is exactly these inspection, parsing, and validation routines that XDoS targets. There are three primary attack vectors that XDoS can navigate Target CPU through recursion: attacker creates a recursive payload and sends to service provider Target memory through jumbo payloads: service provider uses DOM to parse XML. DOM creates in memory representation of XML document, but when document is very large (for example, north of 1 Gb) service provider host may exhaust memory trying to build memory objects. XML Ping of death: attack service provider with numerous small files that clog the system. All of the above attacks exploit the loosely coupled nature of web services, where the service provider has little to no control over the service requester and any messages the service requester sends.
exploit-db via4
description Exim 4.89 - 'BDAT' Denial of Service. CVE-2017-16944. Dos exploit for Multiple platform. Tags: Denial of Service (DoS)
file exploits/multiple/dos/43184.txt
id EDB-ID:43184
last seen 2017-11-27
modified 2017-11-27
platform multiple
port
published 2017-11-27
reporter Exploit-DB
source https://www.exploit-db.com/download/43184/
title Exim 4.89 - 'BDAT' Denial of Service
type dos
nessus via4
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2017-0053BB9719.NASL
    description This is an update fixing denial of service (CVE-2017-16944). ---- This is an update fixing use-after-free (CVE-2017-16943). Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2019-02-21
    modified 2018-02-01
    plugin id 105803
    published 2018-01-15
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=105803
    title Fedora 27 : exim (2017-0053bb9719)
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2017-0032BAA7D7.NASL
    description This is an update fixing denial of service (CVE-2017-16944). ---- This is an update fixing use-after-free (CVE-2017-16943). Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2019-02-21
    modified 2018-02-01
    plugin id 105196
    published 2017-12-13
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=105196
    title Fedora 26 : exim (2017-0032baa7d7)
  • NASL family Gentoo Local Security Checks
    NASL id GENTOO_GLSA-201803-01.NASL
    description The remote host is affected by the vulnerability described in GLSA-201803-01 (Exim: Multiple vulnerabilities) Multiple vulnerabilities have been discovered in Exim. Please review the CVE identifiers referenced below for details. Impact : A remote attacker, by connecting to the SMTP listener daemon, could possibly execute arbitrary code with the privileges of the process or cause a Denial of Service condition. Workaround : There is no known workaround at this time.
    last seen 2019-02-21
    modified 2018-06-07
    plugin id 107178
    published 2018-03-07
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=107178
    title GLSA-201803-01 : Exim: Multiple vulnerabilities
  • NASL family Amazon Linux Local Security Checks
    NASL id ALA_ALAS-2017-932.NASL
    description Use-after-free in receive_msg function via vectors involving BDAT commands The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via vectors involving BDAT commands. (CVE-2017-16943) Infinite loop and stack exhaustion in receive_msg function via vectors involving BDAT commands The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function. (CVE-2017-16944)
    last seen 2019-02-21
    modified 2018-04-18
    plugin id 105417
    published 2017-12-26
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=105417
    title Amazon Linux AMI : exim (ALAS-2017-932)
  • NASL family FreeBSD Local Security Checks
    NASL id FREEBSD_PKG_75DD622CD5FD11E7B9FEC13EB7BCBF4F.NASL
    description Exim developers team reports : The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function.
    last seen 2019-02-21
    modified 2018-11-10
    plugin id 104944
    published 2017-12-01
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=104944
    title FreeBSD : exim -- remote DoS attack in BDAT processing (75dd622c-d5fd-11e7-b9fe-c13eb7bcbf4f)
  • NASL family Ubuntu Local Security Checks
    NASL id UBUNTU_USN-3499-1.NASL
    description It was discovered that Exim incorrectly handled certain BDAT data headers. A remote attacker could possibly use this issue to cause Exim to crash, resulting in a denial of service. Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2019-02-21
    modified 2018-12-01
    plugin id 104882
    published 2017-11-30
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=104882
    title Ubuntu 17.04 / 17.10 : exim4 vulnerability (USN-3499-1)
  • NASL family Debian Local Security Checks
    NASL id DEBIAN_DSA-4053.NASL
    description Several vulnerabilities have been discovered in Exim, a mail transport agent. The Common Vulnerabilities and Exposures project identifies the following issues : - CVE-2017-16943 A use-after-free vulnerability was discovered in Exim's routines responsible for parsing mail headers. A remote attacker can take advantage of this flaw to cause Exim to crash, resulting in a denial of service, or potentially for remote code execution. - CVE-2017-16944 It was discovered that Exim does not properly handle BDAT data headers allowing a remote attacker to cause Exim to crash, resulting in a denial of service.
    last seen 2019-02-21
    modified 2018-11-13
    plugin id 104940
    published 2017-12-01
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=104940
    title Debian DSA-4053-1 : exim4 - security update
packetstorm via4
data source https://packetstormsecurity.com/files/download/145152/exim489-dos.txt
id PACKETSTORM:145152
last seen 2017-12-01
published 2017-11-27
reporter meh
source https://packetstormsecurity.com/files/145152/Exim-4.89-Denial-Of-Service.html
title Exim 4.89 Denial Of Service
refmap via4
debian DSA-4053
exploit-db 43184
misc
sectrack 1039873
the hacker news via4
id THN:EE92331B07B64A7332ABABDA5C30ACC1
last seen 2018-01-27
modified 2017-11-27
published 2017-11-26
reporter Mohit Kumar
source https://thehackernews.com/2017/11/exim-internet-mailer-flaws.html
title Exim Internet Mailer Found Vulnerable to RCE And DoS Bugs; Patch Now
Last major update 25-11-2017 - 12:29
Published 25-11-2017 - 12:29
Last modified 07-12-2017 - 15:19
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