Vulnerabilities > CVE-2008-4501 - Path Traversal vulnerability in Solarwinds Serv-U File Server

047910
CVSS 9.0 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
SINGLE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
network
low complexity
solarwinds
CWE-22
critical
nessus
exploit available

Summary

Directory traversal vulnerability in the FTP server in Serv-U 7.0.0.1 through 7.3, including 7.2.0.1, allows remote authenticated users to overwrite or create arbitrary files via a ..\ (dot dot backslash) in the RNTO command.

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Relative Path Traversal
    An attacker exploits a weakness in input validation on the target by supplying a specially constructed path utilizing dot and slash characters for the purpose of obtaining access to arbitrary files or resources. An attacker modifies a known path on the target in order to reach material that is not available through intended channels. These attacks normally involve adding additional path separators (/ or \) and/or dots (.), or encodings thereof, in various combinations in order to reach parent directories or entirely separate trees of the target's directory structure.
  • Directory Traversal
    An attacker with access to file system resources, either directly or via application logic, will use various file path specification or navigation mechanisms such as ".." in path strings and absolute paths to extend their range of access to inappropriate areas of the file system. The attacker attempts to either explore the file system for recon purposes or access directories and files that are intended to be restricted from their access. Exploring the file system can be achieved through constructing paths presented to directory listing programs, such as "ls" and 'dir', or through specially crafted programs that attempt to explore the file system. The attacker engaging in this type of activity is searching for information that can be used later in a more exploitive attack. Access to restricted directories or files can be achieved through modification of path references utilized by system applications.
  • File System Function Injection, Content Based
    An attack of this type exploits the host's trust in executing remote content including binary files. The files are poisoned with a malicious payload (targeting the file systems accessible by the target software) by the attacker and may be passed through standard channels such as via email, and standard web content like PDF and multimedia files. The attacker exploits known vulnerabilities or handling routines in the target processes. Vulnerabilities of this type have been found in a wide variety of commercial applications from Microsoft Office to Adobe Acrobat and Apple Safari web browser. When the attacker knows the standard handling routines and can identify vulnerabilities and entry points they can be exploited by otherwise seemingly normal content. Once the attack is executed, the attackers' program can access relative directories such as C:\Program Files or other standard system directories to launch further attacks. In a worst case scenario, these programs are combined with other propagation logic and work as a virus.
  • Using Slashes and URL Encoding Combined to Bypass Validation Logic
    This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple way of encoding an URL and abuse the interpretation of the URL. An URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
  • Manipulating Input to File System Calls
    An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

Exploit-Db

descriptionServ-U <= 7.3 Remote FTP File Replacement Vulnerability (auth). CVE-2008-4501. Remote exploit for windows platform
fileexploits/windows/remote/6661.txt
idEDB-ID:6661
last seen2016-02-01
modified2008-10-03
platformwindows
port
published2008-10-03
reporterdmnt
sourcehttps://www.exploit-db.com/download/6661/
titleServ-U <= 7.3 - Remote FTP File Replacement Vulnerability auth
typeremote

Nessus

NASL familyFTP
NASL idSERVU_7_3_0_1.NASL
descriptionThe installed version of Serv-U 7.x is earlier than 7.3.0.1 and thus is reportedly affected by the following issues : - An authenticated, remote attacker can cause the service to consume all CPU time on the remote host by specifying a Windows port (eg,
last seen2020-06-01
modified2020-06-02
plugin id34398
published2008-10-14
reporterThis script is Copyright (C) 2008-2018 Tenable Network Security, Inc.
sourcehttps://www.tenable.com/plugins/nessus/34398
titleServ-U 7.x < 7.3.0.1 Multiple Remote Vulnerabilities (DoS, Traversal)
code
#
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(34398);
  script_version("1.20");
  script_cvs_date("Date: 2018/11/15 20:50:22");

  script_cve_id("CVE-2008-4500", "CVE-2008-4501");
  script_bugtraq_id(31556, 31563);
  script_xref(name:"EDB-ID", value:"6660");
  script_xref(name:"EDB-ID", value:"6661");
  script_xref(name:"Secunia", value:"32150");

  script_name(english:"Serv-U 7.x < 7.3.0.1 Multiple Remote Vulnerabilities (DoS, Traversal)");
  script_summary(english:"Checks Serv-U version");

  script_set_attribute(attribute:"synopsis", value:
"The remote FTP server is affected by several vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The installed version of Serv-U 7.x is earlier than 7.3.0.1 and thus
is reportedly affected by the following issues :

  - An authenticated, remote attacker can cause the service
    to consume all CPU time on the remote host by 
    specifying a Windows port (eg, 'CON:') when using the 
    STOU command provided he has write access to a 
    directory.

  - An authenticated, remote attacker can overwrite or create
    arbitrary files via a directory traversal attack in the
    RNTO command.

  - An authenticated, remote attacker may be able to upload a
    file to the current Windows directory with rename by 
    placing the destination in '\' (ie, 'My Computer').");
  script_set_attribute(attribute:"see_also", value:"http://www.serv-u.com/kb/1769/ServU-7-vs-ServU-6");
  script_set_attribute(attribute:"see_also", value:"https://support.solarwinds.com/Success_Center/Serv-U_Managed_File_Transfer_Serv-U_FTP_Server/Serv-U_Documentation/release_notes");
  script_set_attribute(attribute:"solution", value:"Upgrade to Serv-U version 7.3.0.1 or later.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_cwe_id(20, 22);

  script_set_attribute(attribute:"plugin_publication_date", value:"2008/10/14");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:serv-u:serv-u");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"FTP");

  script_copyright(english:"This script is Copyright (C) 2008-2018 Tenable Network Security, Inc.");

  script_dependencies("servu_version.nasl");
  script_require_keys("ftp/servu");
  script_require_ports("Services/ftp", 21);

  exit(0);
}


include("global_settings.inc");
include("misc_func.inc");
include("ftp_func.inc");


port    = get_ftp_port(default:21);
version = get_kb_item_or_exit('ftp/'+port+'/servu/version');
source  = get_kb_item_or_exit('ftp/'+port+'/servu/source');

if (version !~ "^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$" && version =~ "^7\.3$")
  exit(0, "The Serv-U version, "+version+" on port "+port+" is not granular enough.");

if (
  version =~ "^7\." &&
  ver_compare(ver: version , fix: '7.3.0.1', strict: FALSE) == -1
)
{
  if (report_verbosity > 0)
  {
    report = 
      '\n  Installed version : ' + version +
      '\n  Version source    : ' + source +
      '\n  Fixed version     : 7.3.0.1' +
      '\n';
    security_hole(port: port, extra: report);
  }
  else security_hole(port);
}
else exit(0, "The Serv-U version "+version+" install listening on port "+port+" is not affected.");