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Sensitive information (proxy-auth) is disclosed in system process list #2060

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gfrenoy opened this issue Jun 9, 2020 · 4 comments
Closed

Sensitive information (proxy-auth) is disclosed in system process list #2060

gfrenoy opened this issue Jun 9, 2020 · 4 comments
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@gfrenoy
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@gfrenoy gfrenoy commented Jun 9, 2020

Describe the bug

When accessing a SOCK5 proxy that requires a password authentication ; one has to provide the password on the command line. What is typically consider as a bad practice [1] since it exposes the password in the system process list.

To Reproduce

ncat --proxy 192.168.1.1:1080 --proxy-type socks5 --proxy-auth user:pass 10.1.2.3 8080

run ps aux and recognize the password is displayed in clear text.

Expected behavior

Support the follow syntax:

export NCAT_PROXY_AUTH="user:pass"
ncat --proxy 192.168.1.1:1080 --proxy-type socks5 10.1.2.3 8080

Additional context

[1] https://www.netmeister.org/blog/passing-passwords.html

Alternative solutions

@fyodor
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@fyodor fyodor commented Jun 17, 2020

I like your suggestion and I'm leaving this issue open for (hopefully) future implementation. But in some ways the underlying "vulnerability" is in the system giving sensitive information (the processes and command-line arguments run by other users or admins or system accounts) in the first place. Even ignoring particularly sensitive data like passwords, there are many reasons you might want to keep this information private. You can turn this disclosure off on Linux with the hidepid option and I wish more Linux distributions would do that by default. More details: https://www.cyberciti.biz/faq/linux-hide-processes-from-other-users/

@gfrenoy
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@gfrenoy gfrenoy commented Jun 18, 2020

Thanks for your comment and the link ; it's indeed a good thing to have the proper hidepid option enabled.

That being said, even for my own processes, I'm not comfortable seeing the password when I type ps aux. It could happen that someone else, looking at my screen is accidentally seeing it ; or that I do not pay enough attention when I copy/paste something ; I've also seen monitoring tools listing the running processes and disclose sensitive information accidentally.

All in all, as many other software has done it, it would be a great addition to ncat to do something about it and minimize the risks.

Thanks for anybody who would like to collaborate on this.

Manipulating argv is maybe easier ; if one can point me to the right right direction (ie: let me know in which file it should be changed), I would be happy to give it a try (ie: propose a PR)

@nnposter
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@nnposter nnposter commented Jun 21, 2020

Please give this patch a spin:

* Implements alternative method for passing proxy credentials by environment
  variable NCAT_PROXY_AUTH.
--- a/ncat/docs/ncat.xml
+++ b/ncat/docs/ncat.xml
@@ -481,6 +481,11 @@
           <option>--proxy-type socks5</option>, the form should be
           username:password.  For
           <option>--proxy-type socks4</option>, it should be a username only.</para>
+          <para>These credentials can be alternatively passed onto Ncat by
+          setting environment variable
+          <envar>NCAT_PROXY_AUTH</envar><indexterm><primary><envar>NCAT_PROXY_AUTH</envar> environment variable</primary></indexterm>,
+          which reduces the risk of the credentials being captured in process
+          logs.  (Option <option>--proxy-auth</option>takes precedence.)</para>
         </listitem>
       </varlistentry>
 
--- a/ncat/ncat_main.c
+++ b/ncat/ncat_main.c
@@ -823,6 +823,9 @@
         }
     }
 
+    if (!o.proxy_auth)
+        o.proxy_auth = getenv("NCAT_PROXY_AUTH");
+
     if (o.zerobyte) {
       if (o.listen)
         bye("Services designed for LISTENING can't be used with -z");
@nnposter
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@nnposter nnposter commented Jul 12, 2020

The patch above has been committed as r37956.

@nnposter nnposter self-assigned this Jul 12, 2020
@nmap-bot nmap-bot closed this in 535e638 Jul 12, 2020
res0nat0r added a commit to res0nat0r/nmap that referenced this issue Oct 7, 2020
stef (#1)
* Implement Ncat proxy creds via environment variable. Fixes nmap#2060, closes nmap#2073

* Fix --resume from IPv6 scans

* Use correct default buffer position. Closes nmap#2084

* Clarify upper boundary for variable-length numerical fields

* Make maximize_fdlimit return rlim_t on appropriate platforms. Closes nmap#2085. Fixes nmap#2079

* Credential object is creds.Account, not brute.Account. See nmap#2086

* Clarify location of the Error object

* Use correct default buffer position. Closes nmap#2086

* Minor optimization of url.parse_query()

* Output of matched fingerprints in http-default-accounts. Fixes nmap#2077

* Document that --open implies --defeat-rst-ratelimit since 7.40

* SNMP scripts are enabled on non-standard ports. See nmap#1473

* Increases SQL Server version resolution

* Eliminate reflection false positives in http-shellshock. Closes nmap#2089

* Unify AFP pathname serialization

* Correct AFP name extraction from responses. Closes nmap#2091
FPGetFileDirParms and FPEnumerateExt2 could crash due to unpacking from
out-of-bounds positions. This latent issue got exposed by converting from
bin.unpack to more stringent string.unpack

* Clarified parsing of the volume list in AFP FPGetSrvrParms

* Add cross references between the 2 whois scripts

* Streamline Boolean expressions

* Centralize AFP timestamp conversion to string

* Fix a word-wrapping issue

* Prevent SSH2 KEX confusion. Fixes nmap#2105

* Add ssh2.fetch_host_key() support for group 16

* Handle case of corrupted TCP options with length 0. Fixes nmap#2104

* Add iDRAC9 fingerprint to http-default-accounts. Closes nmap#2096

* fix license url: http -> https

* Implementation of TLS SNI override in Ncat
Closes nmap#2087, closes nmap#1928, fixes nmap#1927, fixes nmap#1974

* Fix off-by-one issue in last change. Fixes nmap#2107

* Be more strict with TCP options parsing, avoid reading off the end of TCP options. See nmap#2107

* Remove nmap-update

This feature was never publicly released, and has not been distributed
in our binary builds for a couple versions now. It needed to be removed
in order to reduce the number of places Nmap looks for data files. See nmap#2051

* If fetchfile didn't find the XSL, use a relative path on all platforms.

* Do not search NMAPDATADIR on Windows as it is not defined. See nmap#2051

* Remove an unused variable

* Require trailing '/' to match a directory name with --script. See nmap#2051

* Stop using Shellshock in header name. Fixes nmap#1983

* Fix line wrapping

* Speed improvement for script afp-ls. Closes nmap#2098

* New option --discovery-ignore-rst. Closes nmap#1616

* Nbase is needed for __attribute__ on Windows

* include string_pool in Windows build

* Use larger buffer size for socket errors (WSAETIMEDOUT was longer).

* Allow multiple UDP payloads per port. Closes nmap#1859 (payloads to be committed later)

* New UDP payloads. Closes nmap#1860

* Use ASCII chars for some payload data where it makes sense

* Pass error along instead of printing (link error)

* OpenSSL 1.1.X renamed libs: libeay32->libcrypto ssleay32->libssl

* More OpenSSL DLL name changes

* One last libeay32->libcrypto name change

* Fix loopback detection on Windows with new Npcap

* Add some popular favicon hashes

* Update nmap-mac-prefixes

* Update nmap-services from IANA

* Handle too-short response in s7-info. See nmap#2117

* Remove a todo item that is done (--resolve-all)

* Update dated 'class' network terms to CIDR. Closes nmap#2054

* Call superclass's init method from derived class

* Use signed value for tcp header offset and option lengths to detect underflow

* Correctly check for unsigned subtraction underflow.

* Add some missing changelog entries

* Tell LGTM to use the correct version of Python (2)

* Process new Linux and OpenBSD fingerprints

* Only get SSL options if we use them, currently for NO_SSLv2

* Process a few service fingerprint submissions

* Add a requested feature

* Try to make sure enough data is present before parsing. See nmap#2117

* Replace hyphens in the client SSH banner
Hyphen is not allowed in the software version string (RFC 4253, section 4.2)

* Update the SSH protocol flow. Closes nmap#1460
Allows the server to start the key exchange before the protocol version
exchange (banner exchange) is completed

* Silence static analysis warning

LGTM points out that since comparison with sizeof(buf) coerces n to
unsigned, all negative values become very large values, which are
necessarily larger than sizeof(buf), so the test is redundant. We still
want the test in our code to be explicit that we are checking for it, so
reordering the comparisons should silence the warning. A good optimizing
compiler should be able to combine the two conditions anyway.

See github/codeql#4249

* Be explicit about truncating division (timeout is in whole milliseconds)

* Improve docs on -Pn and host discovery

"Host discovery" is the preferred term over "ping scan" because of
confusion with ICMP Echo Request, a.k.a. "ping" as used by the "ping"
utility. Warn when users use -Pn because it has negative impact on scan
times since ultrascan timing parameters fall back to slow initial
defaults.

* Fix a config issue with LGTM (libverbs not linked in libpcap)

* Update IPv6 classifier based on new submissions through 2020-09-14

* Fix a meaningless error message when parsing IPv6 extension headers.

* Allow %F date format to mean YYYY-mm-dd like GNU date

* Remove duplicate test conditionals already tested in enclosing block

* Properly handle pcap reads in iocp engine. Fixes nmap#2126

Still has an odd code smell, but this fixes my test case with Nping.

* Add missing prototype

* Make IOCP the default Nsock engine on Windows. See nmap#2126

* Update macosx build to OpenSSL 1.1.1h, use jhbuild for all build steps

* Default rule base for script mysql-audit. See nmap#2125

* Avoid masked use of date before 1/1/1970 UTC. Fixes nmap#2136, closes nmap#2137

* Fix a CHANGELOG typo

* Reintegrate Nmap 7.90 release branch

* Bump version and regen docs for 7.90SVN post-release

* Only warn about protocol specs in port list with -p. Fixes nmap#2135

* Handle a weird IOCP error for UDP sockets. Fixes nmap#2140

Co-authored-by: nnposter <nnposter@e0a8ed71-7df4-0310-8962-fdc924857419>
Co-authored-by: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
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