Is Computer Networking A Top-Down Approach 8th Edition by James W. Kurose, Keith W. Ross.pdf safe?
No antivirus engine detected the long-circulating PDF, and the isolated sandbox technique mappings lack corroborating malware, persistence, or harmful-child evidence.
None of 74 antivirus engines flagged this PDF, including the tier-1 engines, despite more than five years of circulation and 169 submissions. One sandbox produced concerning technique mappings and direct-IP traffic, but it issued no malware finding, showed no persistence, and supplied weak evidence for the claimed process injection.
58e30d5b65824bbff0…4ccdb137bba986Recommended next actions
Before opening
Open it only when its sender or download source is one you independently trust.
If you already opened it
Keep normal device protection enabled and stop if the file behaves unexpectedly.
Intelligence
The saved assessment, checked against the scan evidence and recorded coverage.
The reasoning behind this verdict
This section explains the evidence supporting the verdict and keeps conflicting or missing signals visible.
None of 74 antivirus engines flagged this PDF, including the tier-1 engines, despite more than five years of circulation and 169 submissions. One sandbox produced concerning technique mappings and direct-IP traffic, but it issued no malware finding, showed no persistence, and supplied weak evidence for the claimed process injection.
The PDF received no malicious or suspicious detections from 74 antivirus engines, with 16 tier-1 engines reporting no detection. It has circulated since February 2021 across 156 sources and 169 submissions, reducing the likelihood that it is an undiscovered active threat. One sandbox mapped credential dumping, process injection, and data destruction techniques, but its recorded T1055 evidence merely shows Adobe Acrobat opening the document. The run produced no malicious sandbox verdict or persistence indicators, and none of ten inspected children was identified as malicious. Host-reputation coverage was incomplete because only one host was inspected despite several recorded network contacts, so the network evidence cannot be characterized as fully cleared. No external research rule, known-malware record, engine family label, or malicious-child finding corroborates the concerning heuristic mappings.
What We Detected
None of 74 antivirus engines flagged the PDF, and 16 tier-1 engines reported no detection. The file has been observed since February 2021, with 156 sources submitting it 169 times, yet no malware family label or external research match was found.
Threat Behavior
One sandbox run mapped T1003, T1055, and T1485. However, the saved evidence for T1055 only shows Adobe Acrobat opening the PDF, and the sandbox issued no malicious verdict or persistence finding. Ten written or dropped items were inspected without a malicious-child finding, although their individual verdicts remain unknown. Several IP and URL contacts were recorded, but only one host received a saved reputation check, so complete network-reputation coverage is unavailable.
What To Do Now
Open the document only with a fully updated PDF reader and keep endpoint protection enabled. If it came from an unexpected source, verify the sender and avoid interacting with embedded forms, links, or attachments until its origin is confirmed.
Where this verdict could be wrong3 caveats
- behaviour.offensiveTechniques contains T1003, T1055, and T1485, although the saved evidence does not substantiate the specific harmful actions.
- The sandbox recorded direct-IP contacts to 2.17.148.252 and 18.213.11.84; contactedHosts.inspected=1 is incomplete coverage, so their reputation was not fully resolved.
- All 10 dropped children have unknown individual verdicts despite droppedChildren.hasMaliciousChild=false.
These are the assessment's weak points. If you believe one applies to your file, report the verdict and we'll re-review it.
- 0/74 antivirus engines reported malicious or suspicious results.
- 16 tier-1 engines reported no detection.
- Observed since 2021 across 156 sources and 169 submissions.
- No malicious sandbox verdict or persistence indicators.
- No malicious child, YARAify rule, or MalwareBazaar record.
- Sandbox mappings include T1003, T1055, and T1485.
- Direct-IP traffic included 2.17.148.252 and 18.213.11.84.
- Contacted-host reputation coverage was incomplete.
- The PDF carries an AcroForm tag and may contain interactive content.
- Ten child artifacts lack individual verdicts.
Use an updated PDF reader, keep endpoint protection enabled, and verify the document's source before using forms or links. No quarantine action is indicated by the available evidence.
Coverage & freshness
Complete means the check returned a usable result. It does not mean the file is safe.
Antivirus
Complete0 of 74 engines flagged the file.
Sandbox
Complete1 isolated runtime environment contributed observations.
Network
Partial1 of 4 contacted hosts were cross-checked; coverage is incomplete.
YARA
Complete3 signature or behavior rules matched.
External intel
Complete3 of 3 independent reference sources completed.
Behavior
Plain-English impact first, then the observed runtime evidence.
Runtime flight recorder
Capture complete- 1isolated sandbox run
- 12MITRE ATT&CK techniques
- 9spawned processes
- 4network contacts
- 40filesystem & mutex artifacts
Attack story
Runtime observations grouped by analysis stage. Arrows organize the stages; they do not claim chronology or causality.
Input file
The submitted object
- FileObserved
Computer Networking A Top-Down Approach 8th Edition by James W. Kurose, Keith W. Ross.pdf
58e30d5b65824bbff0331dc624be8247cf92ca30f205e343584ccdb137bba986
01Uploaded file
Processes
Runtime execution
- ProcessObserved
Observed process
"C:\Program Files\Adobe\Acrobat DC\Acrobat\Acrobat.exe" "C:\Users\<USER>\Desktop\attachment.pdf"
02Isolated runtime analysis - ProcessObserved
Observed process
"C:\Program Files\Adobe\Acrobat DC\Acrobat\Adobe Crash Processor.exe"
03Isolated runtime analysis - +1 more recorded observation in Analyst mode
Files
Created or changed
- Written fileObserved
acroNGLLog.txt
C:\Users\<USER>\AppData\Local\Temp\acroNGLLog.txt
04Isolated runtime analysis - Written fileObserved
NGLClient_AcrobatReader123.8.20533.6.log
C:\Users\<USER>\AppData\Local\Temp\NGL\NGLClient_AcrobatReader123.8.20533.6.log
05Isolated runtime analysis - +1 more recorded observation in Analyst mode
Network
Hosts contacted
- Contacted hostObserved
8.8.8.8
Contact observed during runtime.
06Isolated runtime analysis - Contacted hostObserved
2.17.148.252
Contact observed during runtime.
07Isolated runtime analysis - +1 more recorded observation in Analyst mode
7 recorded facts from one runtime window. Every fact remains independently traceable in Analyst mode.
What this file did when executed
This file was detonated in 1 sandbox and its runtime behaviour was observed.
Adversary techniques mapped to the MITRE ATT&CK framework.
- 8.8.8.8
- 2.17.148.252
- 18.213.11.84
- https://ardownload3.adobe.com/pub/adobe/reader/win/AcrobatDC/2200320310/AcroRdrDCUpd2200320310.msi
- C:\Users\<USER>\AppData\Local\Temp\acroNGLLog.txt
- C:\Users\<USER>\AppData\Local\Temp\NGL\NGLClient_AcrobatReader123.8.20533.6.log
- C:\Users\<USER>\AppData\Local\Temp\Tmp2F01.tmp
- C:\Users\<USER>\AppData\Local\Temp\A964s2w7_vxej1i_2bw.tmp
- C:\Users\<USER>\AppData\Local\Adobe\Acrobat\DC\SOPHIA\Reader\SOPHIA.json
- C:\Users\<USER>\AppData\Roaming\Adobe\Acrobat\DC\JSCache\GlobSettings
- C:\Users\<USER>\AppData\Roaming\Adobe\Acrobat\9.0\SharedDataEvents-journal
- C:\Users\<USER>\AppData\Local\Adobe\Acrobat\DC\SOPHIA\Reader\Files\DC_READER_LAUNCH_CARD
- C:\Users\<USER>\AppData\Local\Adobe\Acrobat\DC\SOPHIA\Reader\Files\ACROBAT_READER_MASTER_SURFACEID
- C:\Windows\Temp\3959.txt
- Local\Acrobat Instance Mutex
- Local\SessionImmersiveColorMutex
- Global\MSILOG_edf248ea1db2693GOL.22c23ISM_pmeT_lacoL_ataDppA_onurB_sresU_:C
- Global\AdobeCrashProcessorLocalLowLock
- Local\ZonesCacheCounterMutex
Files this sample writes at runtime
This file drops 10 children at runtime. None are currently flagged malicious in our cache.
- 1b8ec9509c352210e30c…83a3bdNever scannednever seen before
- 4cc23dd7d5c2f85a438b…ecfb69Never scannednever seen before
- 513fb5d3b4195ab59af2…64de2eNever scannednever seen before
- a779a261df447a4c298c…b1b86dNever scannednever seen before
- a6ce2291a38cc10f8e64…b90d1eNever scannednever seen before
- db8a9d9f7851ae708260…5c0669Never scannednever seen before
- 81ff65efc4487853bdb4…7c8e06Never scannednever seen before
- 5a52fba50abaf120d281…050a95Never scannednever seen before
- c9203c5a3e50b7efbae5…9cc34aNever scannednever seen before
- 9df8e969c682f1f44855…20d415Never scannednever seen before
Detection & Forensics
Consensus, attribution, signatures, code structure, prevalence, and identity.
Evidence integrity
Chain of custody for the facts preserved in this report.
- 3rule hits recorded
- 0 / 74engines flagged
- 156sources in submission history
Why these facts are shown
Each statement identifies whether it was directly recorded or derived from saved scan facts.
- 01
0 of 74 antivirus engines flagged the file.
Verdict inputView chapterProvenanceObservedSourceAntivirus analysisObserved at - 02
The hash has a long, established submission history across 156 sources.
Verdict inputView chapterProvenanceDerivedSourceSubmission historyObserved at - 03
1 high-confidence signature or behavior rule matched this file.
Verdict inputView chapterProvenanceDerivedSourceSignature and behavior rulesObserved at - 04
Scanned file: Computer Networking A Top-Down Approach 8th Edition by James W. Kurose, Keith W. Ross.pdf — 58e30d5b65824bbff0331dc624be8247cf92ca30f205e343584ccdb137bba986
ProvenanceObservedSourceUploaded fileObserved at - 05
Observed process — "C:\Program Files\Adobe\Acrobat DC\Acrobat\Acrobat.exe" "C:\Users\<USER>\Desktop\attachment.pdf"
ProvenanceObservedSourceIsolated runtime analysisObserved at - 06
Observed process — "C:\Program Files\Adobe\Acrobat DC\Acrobat\Adobe Crash Processor.exe"
ProvenanceObservedSourceIsolated runtime analysisObserved at - 07
File written: acroNGLLog.txt — C:\Users\<USER>\AppData\Local\Temp\acroNGLLog.txt
ProvenanceObservedSourceIsolated runtime analysisObserved at - 08
File written: NGLClient_AcrobatReader123.8.20533.6.log — C:\Users\<USER>\AppData\Local\Temp\NGL\NGLClient_AcrobatReader123.8.20533.6.log
ProvenanceObservedSourceIsolated runtime analysisObserved at - 09
Contacted host: 8.8.8.8 — Contact observed during runtime.
ProvenanceObservedSourceIsolated runtime analysisObserved at - 10
Contacted host: 2.17.148.252 — Contact observed during runtime.
ProvenanceObservedSourceIsolated runtime analysisObserved at
Detection sources at a glance
The available sources did not agree on a named threat category.
MalwareBazaar, YARAify, and CIRCL hashlookup completed and returned no entries for this hash.
Signatures and behavior heuristics
A community signature or high-severity behavioral heuristic matched. Signatures identify known patterns; heuristics are strong leads but are not proof on their own.
The saved runtime evidence maps this activity to MITRE T1055 (Process Injection). The mapping supports possible process injection, but it does not prove the exact injection method or the operator's intent.
Evidence"C:\Program Files\Adobe\Acrobat DC\Acrobat\Acrobat.exe" "C:\Users\<USER>\Desktop\attachment.pdf"MITRE T1003 (OS Credential Dumping) mapped by at least one sandbox run.
The sample contacted an external IP address directly and no application domain was recorded. Direct-IP traffic also occurs in legitimate installers and infrastructure, so this is supporting context only and requires corroboration from host reputation and other runtime evidence.
Evidence2.17.148.252 · 18.213.11.84
0 of 74 engines flagged this file
View all 74 engine results
PE structure
Not applicablePE structure analysis applies to Windows executable formats, not this file type.
How widely this file has been seen
Widely seen in the wild for a long time. High prior this is legitimate; isolated detections on common-old files are usually false positives.
Fingerprint and provenance
- File name
- Computer Networking A Top-Down Approach 8th Edition by James W. Kurose, Keith W. Ross.pdf
- Format
- Code signing
- Not applicable to this file type
- Size
- 20.5 MB
- Last analyzed
- Sep 9, 2026, 7:04 PM UTC
58e30d5b65824bbff0331dc624be8247cf92ca30f205e343584ccdb137bba986Safety & FAQ
Complete recovery guidance and answers for the next decision.
What to do now
This file appears low risk based on the evidence available now.
- Recovery step 01
Open it only when its sender or download source is one you independently trust.
- Recovery step 02
A clean result reduces known risk, but it cannot guarantee that every new or targeted threat has been detected.
- Recovery step 03
Keep your antivirus and Windows updates switched on so you stay protected.
Safety FAQ
Direct answers grounded in the saved verdict and evidence in this report.
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Community
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