Vulnerabilities > CVE-2016-1494 - Improper Input Validation vulnerability in multiple products

047910
CVSS 5.0 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
PARTIAL
Availability impact
NONE
network
low complexity
python
fedoraproject
opensuse
CWE-20
nessus

Summary

The verify function in the RSA package for Python (Python-RSA) before 3.3 allows attackers to spoof signatures with a small public exponent via crafted signature padding, aka a BERserk attack.

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Server Side Include (SSI) Injection
    An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
  • Cross Zone Scripting
    An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
  • Cross Site Scripting through Log Files
    An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

Nessus

  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2016-C845706426.NASL
    descriptionFix for CVE-2016-1494 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-05
    modified2016-03-04
    plugin id89612
    published2016-03-04
    reporterThis script is Copyright (C) 2016-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/89612
    titleFedora 22 : python-rsa-3.3-2.fc22 (2016-c845706426)
    code
    #%NASL_MIN_LEVEL 80502
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from Fedora Security Advisory 2016-c845706426.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(89612);
      script_version("1.3");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/04");
    
      script_cve_id("CVE-2016-1494");
      script_xref(name:"FEDORA", value:"2016-c845706426");
    
      script_name(english:"Fedora 22 : python-rsa-3.3-2.fc22 (2016-c845706426)");
      script_summary(english:"Checks rpm output for the updated package.");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:"The remote Fedora host is missing a security update."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "Fix for CVE-2016-1494
    
    Note that Tenable Network Security has extracted the preceding
    description block directly from the Fedora security advisory. Tenable
    has attempted to automatically clean and format it as much as possible
    without introducing additional issues."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://bugzilla.redhat.com/show_bug.cgi?id=1295870"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://bugzilla.redhat.com/show_bug.cgi?id=1295871"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://bugzilla.redhat.com/show_bug.cgi?id=1297222"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://bugzilla.redhat.com/show_bug.cgi?id=1298335"
      );
      # https://lists.fedoraproject.org/pipermail/package-announce/2016-January/175942.html
      script_set_attribute(
        attribute:"see_also",
        value:"http://www.nessus.org/u?788b6e25"
      );
      script_set_attribute(
        attribute:"solution", 
        value:"Update the affected python-rsa package."
      );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:python-rsa");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:22");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2016/01/23");
      script_set_attribute(attribute:"plugin_publication_date", value:"2016/03/04");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2016-2020 Tenable Network Security, Inc.");
      script_family(english:"Fedora Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/rpm-list");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("global_settings.inc");
    include("rpm.inc");
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    release = get_kb_item("Host/RedHat/release");
    if (isnull(release) || "Fedora" >!< release) audit(AUDIT_OS_NOT, "Fedora");
    os_ver = eregmatch(pattern: "Fedora.*release ([0-9]+)", string:release);
    if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Fedora");
    os_ver = os_ver[1];
    if (! ereg(pattern:"^22([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 22.x", "Fedora " + os_ver);
    
    if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    cpu = get_kb_item("Host/cpu");
    if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
    if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Fedora", cpu);
    
    flag = 0;
    if (rpm_check(release:"FC22", reference:"python-rsa-3.3-2.fc22")) flag++;
    
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
      else security_warning(0);
      exit(0);
    }
    else
    {
      tested = pkg_tests_get();
      if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
      else audit(AUDIT_PACKAGE_NOT_INSTALLED, "python-rsa");
    }
    
  • NASL familyAmazon Linux Local Security Checks
    NASL idALA_ALAS-2016-644.NASL
    descriptionIt was found that python-rsa is vulnerable to Bleichenbacher
    last seen2020-06-01
    modified2020-06-02
    plugin id88656
    published2016-02-10
    reporterThis script is Copyright (C) 2016-2018 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/88656
    titleAmazon Linux AMI : python-rsa (ALAS-2016-644)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were
    # extracted from Amazon Linux AMI Security Advisory ALAS-2016-644.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(88656);
      script_version("2.3");
      script_cvs_date("Date: 2018/04/18 15:09:35");
    
      script_cve_id("CVE-2016-1494");
      script_xref(name:"ALAS", value:"2016-644");
    
      script_name(english:"Amazon Linux AMI : python-rsa (ALAS-2016-644)");
      script_summary(english:"Checks rpm output for the updated packages");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:"The remote Amazon Linux AMI host is missing a security update."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "It was found that python-rsa is vulnerable to Bleichenbacher'06
    attack, allowing attacker to fake signatures for any public key with
    low exponent. (CVE-2016-1494)"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://alas.aws.amazon.com/ALAS-2016-644.html"
      );
      script_set_attribute(
        attribute:"solution", 
        value:"Run 'yum update python-rsa' to update your system."
      );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python26-rsa");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python27-rsa");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2016/02/09");
      script_set_attribute(attribute:"plugin_publication_date", value:"2016/02/10");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2016-2018 Tenable Network Security, Inc.");
      script_family(english:"Amazon Linux Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("global_settings.inc");
    include("rpm.inc");
    
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    
    release = get_kb_item("Host/AmazonLinux/release");
    if (isnull(release) || !strlen(release)) audit(AUDIT_OS_NOT, "Amazon Linux");
    os_ver = pregmatch(pattern: "^AL(A|\d)", string:release);
    if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
    os_ver = os_ver[1];
    if (os_ver != "A")
    {
      if (os_ver == 'A') os_ver = 'AMI';
      audit(AUDIT_OS_NOT, "Amazon Linux AMI", "Amazon Linux " + os_ver);
    }
    
    if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    
    flag = 0;
    if (rpm_check(release:"ALA", reference:"python26-rsa-3.3-2.7.amzn1")) flag++;
    if (rpm_check(release:"ALA", reference:"python27-rsa-3.3-2.7.amzn1")) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
      else security_warning(0);
      exit(0);
    }
    else
    {
      tested = pkg_tests_get();
      if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
      else audit(AUDIT_PACKAGE_NOT_INSTALLED, "python26-rsa / python27-rsa");
    }
    
  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2016-70EDFBBCEF.NASL
    descriptionFix for CVE-2016-1494 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-05
    modified2016-03-04
    plugin id89566
    published2016-03-04
    reporterThis script is Copyright (C) 2016-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/89566
    titleFedora 23 : python-rsa-3.3-2.fc23 (2016-70edfbbcef)
  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_E78BFC9DCB1E11E5B2510050562A4D7B.NASL
    descriptionFilippo Valsorda reports : python-rsa is vulnerable to a straightforward variant of the Bleichenbacher
    last seen2020-06-01
    modified2020-06-02
    plugin id88585
    published2016-02-05
    reporterThis script is Copyright (C) 2016-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/88585
    titleFreeBSD : py-rsa -- Bleichenbacher'06 signature forgery vulnerability (e78bfc9d-cb1e-11e5-b251-0050562a4d7b)
  • NASL familySuSE Local Security Checks
    NASL idOPENSUSE-2016-33.NASL
    descriptionThis update for python-rsa fixes the following security issues : - CVE-2016-1494: Possible signature forgery via Bleichenbacher attack (bsc#960680) The following bugs fixes are included : - FATE#319904, boo#954690: Support VPN feature in google-cloud-sdk - boo#935595: missing coreutils requirement
    last seen2020-06-05
    modified2016-01-25
    plugin id88123
    published2016-01-25
    reporterThis script is Copyright (C) 2016-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/88123
    titleopenSUSE Security Update : python-rsa (openSUSE-2016-33)