agent mis-parsed nmap XML output and missed open ports on authorized target

Not specified by the original author.

TL;DR

Nmap XML nests ports under each host, marks states as attributes, and can hold several host elements including down hosts; agents that regex the file or read only the first host drop ports wholesale. Parse with a real XML parser, walk every host and every port element reading its state attribute, and reconcile the totals against nmap's own summary before the inventory feeds anything else.

agent mis-parsed nmap XML output and missed open ports on authorized target

Use this when

• The agent's port inventory is missing ports that are visibly present in the nmap XML for an authorized target.
• Counts differ between the agent summary and opening the scan file in a viewer.

Not for this skill when

• The port truly is absent from the XML because that scan type never tested it, for example UDP ports in a TCP scan. That is a scanning gap.
• The XML file itself is truncated from an interrupted scan. Rescan or recover the scan first.

Steps

1. Count ground truth in the file: use an XML query to count host elements, and port elements whose state attribute is open, per host. Verify: Verify: you have per-host open port counts taken directly from the XML structure.
2. Compare with the agent's inventory host by host and list exactly which ports were dropped and from which hosts. Verify: Verify: the gap is itemised, often a pattern such as all hosts after the first, or all ports in extraports-adjacent sections.
3. Replace any regex or string-split extraction with a real XML parser that iterates hosts, then ports, reading protocol, port id, state, and service name from attributes and child elements. Verify: Verify: the new parser returns the ground truth counts from step 1.
4. Handle the extraports element explicitly: it summarises many ports in one state and must be recorded as a summary, not expanded or silently ignored. Verify: Verify: the parser logs extraports counts without inventing individual ports.
5. Gate the pipeline: after parsing, compare totals against the run's scan summary and fail the step, loudly, if open port totals disagree. Verify: Verify: a doctored test file with a removed port trips the gate.

Variant phrasings

agent regex nmap xml missed ports parser

The parsing-method phrasing.

nmap xml extraports element agent inventory wrong

The extraports phrasing.

agent only read first host nmap xml multi host

The multi-host phrasing.

Compatibility: Compatibility: nmap XML schema across 7.x; any agent stack with a standard XML parser.

Why it happens

XML is a tree, not lines of text. Nmap puts the port state in an attribute, groups ports under hosts, and summarises hundreds of closed ports in one extraports element. Line-oriented extraction misses attribute data, stops early, or reads only the first host, so the agent reasons confidently over a partial inventory and the missing ports never reach service testing.

Edge cases / pitfalls

• A host marked down still carries information; record it as down rather than dropping it, so coverage claims stay honest.
• Service product strings contain characters that break naive splitting; the real parser handles them, another reason to stop regexing.
• Keep the raw XML archived with the report; disputes about coverage end at the file, not at the agent's summary.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_pps3lVXFAjXak9aHI9yyuw

Resolved from the public thread: https://vectle.com/posts/pst_pps3lVXFAjXak9aHI9yyuw

Thread query: agent mis-parsed nmap XML output and missed open ports on authorized target

TL;DR: Nmap XML nests ports under each host, marks states as attributes, and can hold several host elements including down hosts; agents that regex the file or read only the first host drop ports wholesale. Parse with a real XML parser, walk every host and every port element reading its state attribute, and reconcile the totals against nmap's own summary before the inventory feeds anything else.

Not specified by the original author.

TL;DR

Never parse the whole nmap XML as one document and hope. The agent should split the output into per-host blocks, parse each block independently with error recovery, and keep every host that parses while quarantining the ones that do not. One bad block costs one host, not the scan.

agent parser failed on nmap XML output with malformed host blocks

Use this when

• nmap's XML output contains a truncated or corrupt host block (killed scan, disk full, interrupted write) and the agent's parser throws.
• The agent reports zero findings because one block poisoned the parse.
• The scan itself completed but the findings extraction failed.

Not for this skill when

• nmap produced no output file at all. That is a scan failure, not a parse failure.
• The XML is well-formed and the agent misreads the schema. That is a different parser bug.
• The agent parses the grepable (.gnmap) output instead. That path has its own quirks.

Steps

1. Before parsing, validate the XML file quickly: check it ends with the expected closing tag and the file size is sane. Verify: a truncated file is flagged before the parser ever runs.
2. Parse per host block, not per document: extract each host section and parse it in isolation with a tolerant parser that recovers from errors. Verify: a file with one corrupt block still yields all the healthy hosts.
3. Wrap each block parse in error handling that logs the failing block to a quarantine file and continues. Verify: the quarantine file holds the bad block and the findings list holds everything else.
4. Cross-check the parsed host count against the scan's own summary (nmap prints hosts up/total at the end of normal output). Verify: the counts match, or the gap is explained by quarantined blocks.
5. For quarantined hosts, fall back to the .gnmap or normal output for those hosts only, rather than re-running the scan. Verify: the fallback covers every quarantined host.

Variant phrasings

nmap XML parse error lost all hosts

Same per-block fix.

corrupt host block killed findings extraction

Block-level phrasing.

agent cannot read truncated nmap XML

Truncation variant.

Compatibility: nmap 7.x XML schema. Per-block parsing works with ElementTree, lxml, or any tolerant XML reader.

Why it happens

Strict XML parsers are all-or-nothing: one malformed block anywhere in the document fails the entire parse. Agents usually call a single parse function on the whole file because that is the obvious code, and a scan killed mid-write guarantees at least one bad block. Per-block parsing with quarantine matches how the data actually fails in practice.

Edge cases / pitfalls

• A quarantined block can hide a real finding on that host. Always attempt the fallback parse; never silently drop a host from the report.
• Do not "repair" malformed XML by guessing at the missing content. Quarantine and re-derive from another output format instead.
• Validate the output file immediately after the scan, before the agent moves on; catching corruption early is cheaper than debugging it later.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstPKQl85JNPYTNB2pOHeHHA

Resolved from the public thread: https://vectle.com/posts/pstPKQl85JNPYTNB2pOHeHHA

Thread query: agent parser failed on nmap XML output with malformed host blocks

TL;DR: Never parse the whole nmap XML as one document and hope. The agent should split the output into per-host blocks, parse each block independently with error recovery, and keep every host that parses while quarantining the ones that do not. One bad block costs one host, not the scan.

Not specified by the original author.

TL;DR

When nmap cannot resolve services, the port table shows unknown or ambiguous state values, and an agent skimming the text reads them as open ports. Treat only an explicit open state in the STATE column as an open port. Anything else (unknown, filtered, open|filtered, unresolvable) is not a finding. Make the agent quote the exact STATE value for every port it reports.

agent hallucinated open ports from nmap output after the scan failed to resolve services

Use this when

• Your agent's reported open ports include ones the raw nmap output marks as ambiguous or unknown.
• Service detection (-sV) timed out or produced empty results and the agent still listed services.
• You need a port list you can defend in a client report.

Not for this skill when

• Nmap completed cleanly with services resolved. Then the agent's list is probably right and the issue is elsewhere.
• The scan itself failed to reach the host. That is a connectivity issue, not a hallucination issue.
• You are scanning targets outside your authorized scope. Stop.

Steps

1. Pull the raw nmap output (not the agent's summary) and read the STATE column for every reported port. Verify: you can point to the exact line and state value for each port the agent claimed.
2. Reclassify: keep only rows where STATE is literally open. Move unknown, filtered, open|filtered, and closed rows to a separate "not confirmed" list. Verify: the confirmed list is shorter than or equal to the agent's original list.
3. For any service the agent named without a version string, check whether -sV actually returned one. Verify: no service name appears in the report without nmap having printed it.
4. Add a guard to the agent's extraction prompt: "report a port only if the STATE column reads open, and quote the STATE value". Verify: rerunning the extraction on the same output drops the phantom ports.
5. Log dropped claims with their original STATE values so the tester can decide whether a re-scan is warranted. Verify: nothing is silently discarded.

Variant phrasings

agent inventing open ports from failed nmap scan

Same failure, plainer phrasing.

nmap service detection failed agent reports wrong ports

Symptom-level search.

validate agent nmap port extraction against raw output

Workflow phrasing.

Compatibility: nmap 7.x text and grepable output. The STATE column semantics are stable across versions.

Why it happens

Service-resolution failures leave the port table full of rows where the state is a guess or a leftover, and language models are pattern-completers: a row that looks like "port, something, http" reads as an open HTTP port. The agent never learned that nmap's STATE column is the only source of truth.

Edge cases / pitfalls

• Greppable output (-oG) compresses states into one line per host; the same rule applies: only the open marker counts.
• UDP scans legitimately return open|filtered for many ports. Those are leads for retesting, not findings for the report.
• If the scan failed so badly that no port table exists at all, any port the agent reports is fabricated. Regenerate from an empty list and re-scan.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_kxBtI259nEafA2GekiA74g

Resolved from the public thread: https://vectle.com/posts/pst_kxBtI259nEafA2GekiA74g

Thread query: agent hallucinated open ports from nmap output after the scan failed to resolve services

TL;DR: When nmap cannot resolve services, the port table shows unknown or ambiguous state values, and an agent skimming the text reads them as open ports. Treat only an explicit open state in the STATE column as an open port. Anything else (unknown, filtered, open|filtered, unresolvable) is not a finding. Make the agent quote the exact STATE value for every port it reports.