Nmap os scan hangs #2104
Labels
Comments
|
after some debugging, I found there is an infinite loop in file Line 1374 in 0acdeb5 |
|
with extra logging, notice that tcpc and optlen are not changing, and the loop goes infinite: |
|
The target has a very weird behavior during OS detection; the TCP End-of-Options-List option is corrupted in many cases, essentially being replaced by 2 random bytes. I will look at our code and see if I can eliminate the parsing problem. |
|
@ameidatou What version of Nmap are you actually using? These values don't match the existing code. It would also be helpful to have a packet capture of a scan where the actual bug triggers. |
|
@dmiller-nmap below is my nmap version: Not sure what you mean by:
and attached are:
|
|
ok, I think I see the issue. If the bogus option has a length of 0, then tcpc += (*tcpc - 1);I'll put in a check for this. |
|
Fix incoming. Interestingly, this bug was introduced in my fix to #1204, which is a transposition of this issue number :) |
|
Thanks @dmiller-nmap for your quick feedback and quick fix! |
Merged
res0nat0r
added a commit
to res0nat0r/nmap
that referenced
this issue
Oct 7, 2020
* 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>
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
and others
Bug
When triggering a nmap OS scan for a specific host, nmap hangs with CPU usage 100%. This doesn't happen systematically but quite often
To Reproduce
sudo nmap -O -p 1027,1028,5000,443,8081,80,8080,1026,1025 --open -Pn -ddd -vv 85.2.144.13if it doesn't happen the first time, please repeat for 3 to 5 times and you should encounter the issue.
The log hangs at this point
Expected behavior
Nmap os scan finishes in less than 30s.
Version info (please complete the following information):
Linux 5.4.0-42-generic #46~18.04.1-Ubuntu x86_64 x86_64 x86_64 GNU/Linuxnmap --version:The text was updated successfully, but these errors were encountered: